mirror of git://gcc.gnu.org/git/gcc.git
2835 lines
63 KiB
C
2835 lines
63 KiB
C
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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#include <limits.h>
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#include <signal.h>
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#include <stdlib.h>
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#include <pthread.h>
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#include <unistd.h>
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#include "config.h"
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#ifdef HAVE_DL_ITERATE_PHDR
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#include <link.h>
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#endif
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#include "runtime.h"
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#include "arch.h"
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#include "defs.h"
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#include "malloc.h"
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#include "race.h"
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#include "go-type.h"
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#include "go-defer.h"
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#ifdef USING_SPLIT_STACK
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/* FIXME: These are not declared anywhere. */
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extern void __splitstack_getcontext(void *context[10]);
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extern void __splitstack_setcontext(void *context[10]);
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extern void *__splitstack_makecontext(size_t, void *context[10], size_t *);
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extern void * __splitstack_resetcontext(void *context[10], size_t *);
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extern void *__splitstack_find(void *, void *, size_t *, void **, void **,
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void **);
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extern void __splitstack_block_signals (int *, int *);
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extern void __splitstack_block_signals_context (void *context[10], int *,
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int *);
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#endif
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#ifndef PTHREAD_STACK_MIN
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# define PTHREAD_STACK_MIN 8192
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#endif
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#if defined(USING_SPLIT_STACK) && defined(LINKER_SUPPORTS_SPLIT_STACK)
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# define StackMin PTHREAD_STACK_MIN
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#else
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# define StackMin 2 * 1024 * 1024
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#endif
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uintptr runtime_stacks_sys;
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static void gtraceback(G*);
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#ifdef __rtems__
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#define __thread
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#endif
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static __thread G *g;
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static __thread M *m;
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#ifndef SETCONTEXT_CLOBBERS_TLS
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static inline void
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initcontext(void)
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{
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}
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static inline void
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fixcontext(ucontext_t *c __attribute__ ((unused)))
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{
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}
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#else
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# if defined(__x86_64__) && defined(__sun__)
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// x86_64 Solaris 10 and 11 have a bug: setcontext switches the %fs
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// register to that of the thread which called getcontext. The effect
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// is that the address of all __thread variables changes. This bug
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// also affects pthread_self() and pthread_getspecific. We work
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// around it by clobbering the context field directly to keep %fs the
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// same.
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static __thread greg_t fs;
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static inline void
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initcontext(void)
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{
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ucontext_t c;
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getcontext(&c);
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fs = c.uc_mcontext.gregs[REG_FSBASE];
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}
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static inline void
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fixcontext(ucontext_t* c)
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{
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c->uc_mcontext.gregs[REG_FSBASE] = fs;
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}
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# elif defined(__NetBSD__)
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// NetBSD has a bug: setcontext clobbers tlsbase, we need to save
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// and restore it ourselves.
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static __thread __greg_t tlsbase;
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static inline void
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initcontext(void)
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{
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ucontext_t c;
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getcontext(&c);
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tlsbase = c.uc_mcontext._mc_tlsbase;
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}
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static inline void
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fixcontext(ucontext_t* c)
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{
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c->uc_mcontext._mc_tlsbase = tlsbase;
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}
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# else
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# error unknown case for SETCONTEXT_CLOBBERS_TLS
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# endif
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#endif
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// We can not always refer to the TLS variables directly. The
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// compiler will call tls_get_addr to get the address of the variable,
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// and it may hold it in a register across a call to schedule. When
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// we get back from the call we may be running in a different thread,
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// in which case the register now points to the TLS variable for a
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// different thread. We use non-inlinable functions to avoid this
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// when necessary.
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G* runtime_g(void) __attribute__ ((noinline, no_split_stack));
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G*
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runtime_g(void)
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{
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return g;
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}
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M* runtime_m(void) __attribute__ ((noinline, no_split_stack));
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M*
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runtime_m(void)
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{
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return m;
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}
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// Set m and g.
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void
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runtime_setmg(M* mp, G* gp)
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{
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m = mp;
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g = gp;
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}
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// The static TLS size. See runtime_newm.
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static int tlssize;
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// Start a new thread.
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static void
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runtime_newosproc(M *mp)
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{
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pthread_attr_t attr;
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size_t stacksize;
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sigset_t clear, old;
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pthread_t tid;
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int ret;
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if(pthread_attr_init(&attr) != 0)
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runtime_throw("pthread_attr_init");
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if(pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED) != 0)
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runtime_throw("pthread_attr_setdetachstate");
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stacksize = PTHREAD_STACK_MIN;
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// With glibc before version 2.16 the static TLS size is taken
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// out of the stack size, and we get an error or a crash if
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// there is not enough stack space left. Add it back in if we
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// can, in case the program uses a lot of TLS space. FIXME:
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// This can be disabled in glibc 2.16 and later, if the bug is
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// indeed fixed then.
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stacksize += tlssize;
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if(pthread_attr_setstacksize(&attr, stacksize) != 0)
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runtime_throw("pthread_attr_setstacksize");
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// Block signals during pthread_create so that the new thread
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// starts with signals disabled. It will enable them in minit.
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sigfillset(&clear);
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#ifdef SIGTRAP
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// Blocking SIGTRAP reportedly breaks gdb on Alpha GNU/Linux.
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sigdelset(&clear, SIGTRAP);
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#endif
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sigemptyset(&old);
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sigprocmask(SIG_BLOCK, &clear, &old);
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ret = pthread_create(&tid, &attr, runtime_mstart, mp);
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sigprocmask(SIG_SETMASK, &old, nil);
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if (ret != 0)
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runtime_throw("pthread_create");
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}
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// First function run by a new goroutine. This replaces gogocall.
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static void
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kickoff(void)
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{
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void (*fn)(void*);
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if(g->traceback != nil)
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gtraceback(g);
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fn = (void (*)(void*))(g->entry);
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fn(g->param);
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runtime_goexit();
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}
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// Switch context to a different goroutine. This is like longjmp.
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static void runtime_gogo(G*) __attribute__ ((noinline));
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static void
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runtime_gogo(G* newg)
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{
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#ifdef USING_SPLIT_STACK
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__splitstack_setcontext(&newg->stack_context[0]);
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#endif
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g = newg;
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newg->fromgogo = true;
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fixcontext(&newg->context);
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setcontext(&newg->context);
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runtime_throw("gogo setcontext returned");
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}
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// Save context and call fn passing g as a parameter. This is like
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// setjmp. Because getcontext always returns 0, unlike setjmp, we use
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// g->fromgogo as a code. It will be true if we got here via
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// setcontext. g == nil the first time this is called in a new m.
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static void runtime_mcall(void (*)(G*)) __attribute__ ((noinline));
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static void
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runtime_mcall(void (*pfn)(G*))
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{
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M *mp;
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G *gp;
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#ifndef USING_SPLIT_STACK
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int i;
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#endif
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// Ensure that all registers are on the stack for the garbage
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// collector.
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__builtin_unwind_init();
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mp = m;
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gp = g;
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if(gp == mp->g0)
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runtime_throw("runtime: mcall called on m->g0 stack");
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if(gp != nil) {
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#ifdef USING_SPLIT_STACK
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__splitstack_getcontext(&g->stack_context[0]);
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#else
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gp->gcnext_sp = &i;
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#endif
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gp->fromgogo = false;
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getcontext(&gp->context);
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// When we return from getcontext, we may be running
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// in a new thread. That means that m and g may have
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// changed. They are global variables so we will
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// reload them, but the addresses of m and g may be
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// cached in our local stack frame, and those
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// addresses may be wrong. Call functions to reload
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// the values for this thread.
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mp = runtime_m();
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gp = runtime_g();
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if(gp->traceback != nil)
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gtraceback(gp);
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}
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if (gp == nil || !gp->fromgogo) {
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#ifdef USING_SPLIT_STACK
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__splitstack_setcontext(&mp->g0->stack_context[0]);
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#endif
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mp->g0->entry = (byte*)pfn;
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mp->g0->param = gp;
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// It's OK to set g directly here because this case
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// can not occur if we got here via a setcontext to
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// the getcontext call just above.
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g = mp->g0;
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fixcontext(&mp->g0->context);
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setcontext(&mp->g0->context);
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runtime_throw("runtime: mcall function returned");
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}
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}
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#ifdef HAVE_DL_ITERATE_PHDR
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// Called via dl_iterate_phdr.
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static int
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addtls(struct dl_phdr_info* info, size_t size __attribute__ ((unused)), void *data)
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{
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size_t *total = (size_t *)data;
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unsigned int i;
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for(i = 0; i < info->dlpi_phnum; ++i) {
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if(info->dlpi_phdr[i].p_type == PT_TLS)
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*total += info->dlpi_phdr[i].p_memsz;
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}
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return 0;
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}
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// Set the total TLS size.
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static void
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inittlssize()
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{
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size_t total = 0;
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dl_iterate_phdr(addtls, (void *)&total);
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tlssize = total;
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}
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#else
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static void
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inittlssize()
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{
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}
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#endif
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// Goroutine scheduler
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// The scheduler's job is to distribute ready-to-run goroutines over worker threads.
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//
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// The main concepts are:
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// G - goroutine.
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// M - worker thread, or machine.
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// P - processor, a resource that is required to execute Go code.
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// M must have an associated P to execute Go code, however it can be
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// blocked or in a syscall w/o an associated P.
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//
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// Design doc at http://golang.org/s/go11sched.
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typedef struct Sched Sched;
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struct Sched {
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Lock;
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uint64 goidgen;
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M* midle; // idle m's waiting for work
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int32 nmidle; // number of idle m's waiting for work
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int32 mlocked; // number of locked m's waiting for work
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int32 mcount; // number of m's that have been created
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P* pidle; // idle P's
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uint32 npidle;
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uint32 nmspinning;
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// Global runnable queue.
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G* runqhead;
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G* runqtail;
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int32 runqsize;
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// Global cache of dead G's.
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Lock gflock;
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G* gfree;
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int32 stopwait;
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Note stopnote;
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uint32 sysmonwait;
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Note sysmonnote;
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uint64 lastpoll;
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int32 profilehz; // cpu profiling rate
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};
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// The max value of GOMAXPROCS.
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// There are no fundamental restrictions on the value.
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enum { MaxGomaxprocs = 1<<8 };
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Sched runtime_sched;
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int32 runtime_gomaxprocs;
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bool runtime_singleproc;
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bool runtime_iscgo = true;
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uint32 runtime_needextram = 1;
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uint32 runtime_gcwaiting;
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M runtime_m0;
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G runtime_g0; // idle goroutine for m0
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G* runtime_allg;
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G* runtime_lastg;
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M* runtime_allm;
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P** runtime_allp;
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M* runtime_extram;
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int8* runtime_goos;
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int32 runtime_ncpu;
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static int32 newprocs;
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void* runtime_mstart(void*);
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static void runqput(P*, G*);
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static G* runqget(P*);
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static void runqgrow(P*);
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static G* runqsteal(P*, P*);
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static void mput(M*);
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static M* mget(void);
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static void mcommoninit(M*);
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static void schedule(void);
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static void procresize(int32);
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static void acquirep(P*);
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static P* releasep(void);
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static void newm(void(*)(void), P*);
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static void stopm(void);
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static void startm(P*, bool);
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static void handoffp(P*);
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static void wakep(void);
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static void stoplockedm(void);
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static void startlockedm(G*);
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static void sysmon(void);
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static uint32 retake(uint32*);
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static void inclocked(int32);
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static void checkdead(void);
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static void exitsyscall0(G*);
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static void park0(G*);
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static void gosched0(G*);
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static void goexit0(G*);
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static void gfput(P*, G*);
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static G* gfget(P*);
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static void gfpurge(P*);
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static void globrunqput(G*);
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static G* globrunqget(P*);
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static P* pidleget(void);
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static void pidleput(P*);
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static void injectglist(G*);
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// The bootstrap sequence is:
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//
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// call osinit
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// call schedinit
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// make & queue new G
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// call runtime_mstart
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//
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// The new G calls runtime_main.
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void
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runtime_schedinit(void)
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{
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int32 n, procs;
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const byte *p;
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m = &runtime_m0;
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g = &runtime_g0;
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m->g0 = g;
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m->curg = g;
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g->m = m;
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initcontext();
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inittlssize();
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m->nomemprof++;
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runtime_mprofinit();
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runtime_mallocinit();
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mcommoninit(m);
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runtime_goargs();
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runtime_goenvs();
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// For debugging:
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// Allocate internal symbol table representation now,
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// so that we don't need to call malloc when we crash.
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// runtime_findfunc(0);
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runtime_sched.lastpoll = runtime_nanotime();
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procs = 1;
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p = runtime_getenv("GOMAXPROCS");
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if(p != nil && (n = runtime_atoi(p)) > 0) {
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if(n > MaxGomaxprocs)
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n = MaxGomaxprocs;
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procs = n;
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}
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runtime_allp = runtime_malloc((MaxGomaxprocs+1)*sizeof(runtime_allp[0]));
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procresize(procs);
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// Can not enable GC until all roots are registered.
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// mstats.enablegc = 1;
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m->nomemprof--;
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}
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extern void main_init(void) __asm__ (GOSYM_PREFIX "__go_init_main");
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extern void main_main(void) __asm__ (GOSYM_PREFIX "main.main");
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// The main goroutine.
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void
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runtime_main(void* dummy __attribute__((unused)))
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{
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newm(sysmon, nil);
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// Lock the main goroutine onto this, the main OS thread,
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// during initialization. Most programs won't care, but a few
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// do require certain calls to be made by the main thread.
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// Those can arrange for main.main to run in the main thread
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// by calling runtime.LockOSThread during initialization
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// to preserve the lock.
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runtime_lockOSThread();
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if(m != &runtime_m0)
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runtime_throw("runtime_main not on m0");
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__go_go(runtime_MHeap_Scavenger, nil);
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main_init();
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runtime_unlockOSThread();
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// For gccgo we have to wait until after main is initialized
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// to enable GC, because initializing main registers the GC
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// roots.
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mstats.enablegc = 1;
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main_main();
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if(raceenabled)
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runtime_racefini();
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// Make racy client program work: if panicking on
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// another goroutine at the same time as main returns,
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// let the other goroutine finish printing the panic trace.
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// Once it does, it will exit. See issue 3934.
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if(runtime_panicking)
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runtime_park(nil, nil, "panicwait");
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runtime_exit(0);
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for(;;)
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*(int32*)0 = 0;
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}
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void
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runtime_goroutineheader(G *gp)
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{
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const char *status;
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switch(gp->status) {
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case Gidle:
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status = "idle";
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break;
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case Grunnable:
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status = "runnable";
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break;
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case Grunning:
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status = "running";
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break;
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case Gsyscall:
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status = "syscall";
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break;
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case Gwaiting:
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if(gp->waitreason)
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status = gp->waitreason;
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else
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status = "waiting";
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break;
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default:
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status = "???";
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|
break;
|
|
}
|
|
runtime_printf("goroutine %D [%s]:\n", gp->goid, status);
|
|
}
|
|
|
|
void
|
|
runtime_goroutinetrailer(G *g)
|
|
{
|
|
if(g != nil && g->gopc != 0 && g->goid != 1) {
|
|
String fn;
|
|
String file;
|
|
intgo line;
|
|
|
|
if(__go_file_line(g->gopc - 1, &fn, &file, &line)) {
|
|
runtime_printf("created by %S\n", fn);
|
|
runtime_printf("\t%S:%D\n", file, (int64) line);
|
|
}
|
|
}
|
|
}
|
|
|
|
struct Traceback
|
|
{
|
|
G* gp;
|
|
Location locbuf[100];
|
|
int32 c;
|
|
};
|
|
|
|
void
|
|
runtime_tracebackothers(G * volatile me)
|
|
{
|
|
G * volatile gp;
|
|
Traceback tb;
|
|
int32 traceback;
|
|
|
|
tb.gp = me;
|
|
traceback = runtime_gotraceback(nil);
|
|
for(gp = runtime_allg; gp != nil; gp = gp->alllink) {
|
|
if(gp == me || gp->status == Gdead)
|
|
continue;
|
|
if(gp->issystem && traceback < 2)
|
|
continue;
|
|
runtime_printf("\n");
|
|
runtime_goroutineheader(gp);
|
|
|
|
// Our only mechanism for doing a stack trace is
|
|
// _Unwind_Backtrace. And that only works for the
|
|
// current thread, not for other random goroutines.
|
|
// So we need to switch context to the goroutine, get
|
|
// the backtrace, and then switch back.
|
|
|
|
// This means that if g is running or in a syscall, we
|
|
// can't reliably print a stack trace. FIXME.
|
|
if(gp->status == Gsyscall || gp->status == Grunning) {
|
|
runtime_printf("no stack trace available\n");
|
|
runtime_goroutinetrailer(gp);
|
|
continue;
|
|
}
|
|
|
|
gp->traceback = &tb;
|
|
|
|
#ifdef USING_SPLIT_STACK
|
|
__splitstack_getcontext(&me->stack_context[0]);
|
|
#endif
|
|
getcontext(&me->context);
|
|
|
|
if(gp->traceback != nil) {
|
|
runtime_gogo(gp);
|
|
}
|
|
|
|
runtime_printtrace(tb.locbuf, tb.c, false);
|
|
runtime_goroutinetrailer(gp);
|
|
}
|
|
}
|
|
|
|
// Do a stack trace of gp, and then restore the context to
|
|
// gp->dotraceback.
|
|
|
|
static void
|
|
gtraceback(G* gp)
|
|
{
|
|
Traceback* traceback;
|
|
|
|
traceback = gp->traceback;
|
|
gp->traceback = nil;
|
|
traceback->c = runtime_callers(1, traceback->locbuf,
|
|
sizeof traceback->locbuf / sizeof traceback->locbuf[0]);
|
|
runtime_gogo(traceback->gp);
|
|
}
|
|
|
|
static void
|
|
mcommoninit(M *mp)
|
|
{
|
|
// If there is no mcache runtime_callers() will crash,
|
|
// and we are most likely in sysmon thread so the stack is senseless anyway.
|
|
if(m->mcache)
|
|
runtime_callers(1, mp->createstack, nelem(mp->createstack));
|
|
|
|
mp->fastrand = 0x49f6428aUL + mp->id + runtime_cputicks();
|
|
|
|
runtime_lock(&runtime_sched);
|
|
mp->id = runtime_sched.mcount++;
|
|
|
|
runtime_mpreinit(mp);
|
|
|
|
// Add to runtime_allm so garbage collector doesn't free m
|
|
// when it is just in a register or thread-local storage.
|
|
mp->alllink = runtime_allm;
|
|
// runtime_NumCgoCall() iterates over allm w/o schedlock,
|
|
// so we need to publish it safely.
|
|
runtime_atomicstorep(&runtime_allm, mp);
|
|
runtime_unlock(&runtime_sched);
|
|
}
|
|
|
|
// Mark gp ready to run.
|
|
void
|
|
runtime_ready(G *gp)
|
|
{
|
|
// Mark runnable.
|
|
if(gp->status != Gwaiting) {
|
|
runtime_printf("goroutine %D has status %d\n", gp->goid, gp->status);
|
|
runtime_throw("bad g->status in ready");
|
|
}
|
|
gp->status = Grunnable;
|
|
runqput(m->p, gp);
|
|
if(runtime_atomicload(&runtime_sched.npidle) != 0 && runtime_atomicload(&runtime_sched.nmspinning) == 0) // TODO: fast atomic
|
|
wakep();
|
|
}
|
|
|
|
int32
|
|
runtime_gcprocs(void)
|
|
{
|
|
int32 n;
|
|
|
|
// Figure out how many CPUs to use during GC.
|
|
// Limited by gomaxprocs, number of actual CPUs, and MaxGcproc.
|
|
runtime_lock(&runtime_sched);
|
|
n = runtime_gomaxprocs;
|
|
if(n > runtime_ncpu)
|
|
n = runtime_ncpu > 0 ? runtime_ncpu : 1;
|
|
if(n > MaxGcproc)
|
|
n = MaxGcproc;
|
|
if(n > runtime_sched.nmidle+1) // one M is currently running
|
|
n = runtime_sched.nmidle+1;
|
|
runtime_unlock(&runtime_sched);
|
|
return n;
|
|
}
|
|
|
|
static bool
|
|
needaddgcproc(void)
|
|
{
|
|
int32 n;
|
|
|
|
runtime_lock(&runtime_sched);
|
|
n = runtime_gomaxprocs;
|
|
if(n > runtime_ncpu)
|
|
n = runtime_ncpu;
|
|
if(n > MaxGcproc)
|
|
n = MaxGcproc;
|
|
n -= runtime_sched.nmidle+1; // one M is currently running
|
|
runtime_unlock(&runtime_sched);
|
|
return n > 0;
|
|
}
|
|
|
|
void
|
|
runtime_helpgc(int32 nproc)
|
|
{
|
|
M *mp;
|
|
int32 n, pos;
|
|
|
|
runtime_lock(&runtime_sched);
|
|
pos = 0;
|
|
for(n = 1; n < nproc; n++) { // one M is currently running
|
|
if(runtime_allp[pos]->mcache == m->mcache)
|
|
pos++;
|
|
mp = mget();
|
|
if(mp == nil)
|
|
runtime_throw("runtime_gcprocs inconsistency");
|
|
mp->helpgc = n;
|
|
mp->mcache = runtime_allp[pos]->mcache;
|
|
pos++;
|
|
runtime_notewakeup(&mp->park);
|
|
}
|
|
runtime_unlock(&runtime_sched);
|
|
}
|
|
|
|
void
|
|
runtime_stoptheworld(void)
|
|
{
|
|
int32 i;
|
|
uint32 s;
|
|
P *p;
|
|
bool wait;
|
|
|
|
runtime_lock(&runtime_sched);
|
|
runtime_sched.stopwait = runtime_gomaxprocs;
|
|
runtime_atomicstore((uint32*)&runtime_gcwaiting, 1);
|
|
// stop current P
|
|
m->p->status = Pgcstop;
|
|
runtime_sched.stopwait--;
|
|
// try to retake all P's in Psyscall status
|
|
for(i = 0; i < runtime_gomaxprocs; i++) {
|
|
p = runtime_allp[i];
|
|
s = p->status;
|
|
if(s == Psyscall && runtime_cas(&p->status, s, Pgcstop))
|
|
runtime_sched.stopwait--;
|
|
}
|
|
// stop idle P's
|
|
while((p = pidleget()) != nil) {
|
|
p->status = Pgcstop;
|
|
runtime_sched.stopwait--;
|
|
}
|
|
wait = runtime_sched.stopwait > 0;
|
|
runtime_unlock(&runtime_sched);
|
|
|
|
// wait for remaining P's to stop voluntary
|
|
if(wait) {
|
|
runtime_notesleep(&runtime_sched.stopnote);
|
|
runtime_noteclear(&runtime_sched.stopnote);
|
|
}
|
|
if(runtime_sched.stopwait)
|
|
runtime_throw("stoptheworld: not stopped");
|
|
for(i = 0; i < runtime_gomaxprocs; i++) {
|
|
p = runtime_allp[i];
|
|
if(p->status != Pgcstop)
|
|
runtime_throw("stoptheworld: not stopped");
|
|
}
|
|
}
|
|
|
|
static void
|
|
mhelpgc(void)
|
|
{
|
|
m->helpgc = -1;
|
|
}
|
|
|
|
void
|
|
runtime_starttheworld(void)
|
|
{
|
|
P *p, *p1;
|
|
M *mp;
|
|
G *gp;
|
|
bool add;
|
|
|
|
gp = runtime_netpoll(false); // non-blocking
|
|
injectglist(gp);
|
|
add = needaddgcproc();
|
|
runtime_lock(&runtime_sched);
|
|
if(newprocs) {
|
|
procresize(newprocs);
|
|
newprocs = 0;
|
|
} else
|
|
procresize(runtime_gomaxprocs);
|
|
runtime_gcwaiting = 0;
|
|
|
|
p1 = nil;
|
|
while((p = pidleget()) != nil) {
|
|
// procresize() puts p's with work at the beginning of the list.
|
|
// Once we reach a p without a run queue, the rest don't have one either.
|
|
if(p->runqhead == p->runqtail) {
|
|
pidleput(p);
|
|
break;
|
|
}
|
|
mp = mget();
|
|
if(mp == nil) {
|
|
p->link = p1;
|
|
p1 = p;
|
|
continue;
|
|
}
|
|
if(mp->nextp)
|
|
runtime_throw("starttheworld: inconsistent mp->nextp");
|
|
mp->nextp = p;
|
|
runtime_notewakeup(&mp->park);
|
|
}
|
|
if(runtime_sched.sysmonwait) {
|
|
runtime_sched.sysmonwait = false;
|
|
runtime_notewakeup(&runtime_sched.sysmonnote);
|
|
}
|
|
runtime_unlock(&runtime_sched);
|
|
|
|
while(p1) {
|
|
p = p1;
|
|
p1 = p1->link;
|
|
add = false;
|
|
newm(nil, p);
|
|
}
|
|
|
|
if(add) {
|
|
// If GC could have used another helper proc, start one now,
|
|
// in the hope that it will be available next time.
|
|
// It would have been even better to start it before the collection,
|
|
// but doing so requires allocating memory, so it's tricky to
|
|
// coordinate. This lazy approach works out in practice:
|
|
// we don't mind if the first couple gc rounds don't have quite
|
|
// the maximum number of procs.
|
|
newm(mhelpgc, nil);
|
|
}
|
|
}
|
|
|
|
// Called to start an M.
|
|
void*
|
|
runtime_mstart(void* mp)
|
|
{
|
|
m = (M*)mp;
|
|
g = m->g0;
|
|
|
|
initcontext();
|
|
|
|
g->entry = nil;
|
|
g->param = nil;
|
|
|
|
// Record top of stack for use by mcall.
|
|
// Once we call schedule we're never coming back,
|
|
// so other calls can reuse this stack space.
|
|
#ifdef USING_SPLIT_STACK
|
|
__splitstack_getcontext(&g->stack_context[0]);
|
|
#else
|
|
g->gcinitial_sp = ∓
|
|
// Setting gcstack_size to 0 is a marker meaning that gcinitial_sp
|
|
// is the top of the stack, not the bottom.
|
|
g->gcstack_size = 0;
|
|
g->gcnext_sp = ∓
|
|
#endif
|
|
getcontext(&g->context);
|
|
|
|
if(g->entry != nil) {
|
|
// Got here from mcall.
|
|
void (*pfn)(G*) = (void (*)(G*))g->entry;
|
|
G* gp = (G*)g->param;
|
|
pfn(gp);
|
|
*(int*)0x21 = 0x21;
|
|
}
|
|
runtime_minit();
|
|
|
|
#ifdef USING_SPLIT_STACK
|
|
{
|
|
int dont_block_signals = 0;
|
|
__splitstack_block_signals(&dont_block_signals, nil);
|
|
}
|
|
#endif
|
|
|
|
// Install signal handlers; after minit so that minit can
|
|
// prepare the thread to be able to handle the signals.
|
|
if(m == &runtime_m0) {
|
|
runtime_initsig();
|
|
if(runtime_iscgo)
|
|
runtime_newextram();
|
|
}
|
|
|
|
if(m->mstartfn)
|
|
m->mstartfn();
|
|
|
|
if(m->helpgc) {
|
|
m->helpgc = 0;
|
|
stopm();
|
|
} else if(m != &runtime_m0) {
|
|
acquirep(m->nextp);
|
|
m->nextp = nil;
|
|
}
|
|
schedule();
|
|
|
|
// TODO(brainman): This point is never reached, because scheduler
|
|
// does not release os threads at the moment. But once this path
|
|
// is enabled, we must remove our seh here.
|
|
|
|
return nil;
|
|
}
|
|
|
|
typedef struct CgoThreadStart CgoThreadStart;
|
|
struct CgoThreadStart
|
|
{
|
|
M *m;
|
|
G *g;
|
|
void (*fn)(void);
|
|
};
|
|
|
|
// Allocate a new m unassociated with any thread.
|
|
// Can use p for allocation context if needed.
|
|
M*
|
|
runtime_allocm(P *p, int32 stacksize, byte** ret_g0_stack, size_t* ret_g0_stacksize)
|
|
{
|
|
M *mp;
|
|
|
|
m->locks++; // disable GC because it can be called from sysmon
|
|
if(m->p == nil)
|
|
acquirep(p); // temporarily borrow p for mallocs in this function
|
|
#if 0
|
|
if(mtype == nil) {
|
|
Eface e;
|
|
runtime_gc_m_ptr(&e);
|
|
mtype = ((const PtrType*)e.__type_descriptor)->__element_type;
|
|
}
|
|
#endif
|
|
|
|
mp = runtime_mal(sizeof *mp);
|
|
mcommoninit(mp);
|
|
mp->g0 = runtime_malg(stacksize, ret_g0_stack, ret_g0_stacksize);
|
|
|
|
if(p == m->p)
|
|
releasep();
|
|
m->locks--;
|
|
|
|
return mp;
|
|
}
|
|
|
|
static M* lockextra(bool nilokay);
|
|
static void unlockextra(M*);
|
|
|
|
// needm is called when a cgo callback happens on a
|
|
// thread without an m (a thread not created by Go).
|
|
// In this case, needm is expected to find an m to use
|
|
// and return with m, g initialized correctly.
|
|
// Since m and g are not set now (likely nil, but see below)
|
|
// needm is limited in what routines it can call. In particular
|
|
// it can only call nosplit functions (textflag 7) and cannot
|
|
// do any scheduling that requires an m.
|
|
//
|
|
// In order to avoid needing heavy lifting here, we adopt
|
|
// the following strategy: there is a stack of available m's
|
|
// that can be stolen. Using compare-and-swap
|
|
// to pop from the stack has ABA races, so we simulate
|
|
// a lock by doing an exchange (via casp) to steal the stack
|
|
// head and replace the top pointer with MLOCKED (1).
|
|
// This serves as a simple spin lock that we can use even
|
|
// without an m. The thread that locks the stack in this way
|
|
// unlocks the stack by storing a valid stack head pointer.
|
|
//
|
|
// In order to make sure that there is always an m structure
|
|
// available to be stolen, we maintain the invariant that there
|
|
// is always one more than needed. At the beginning of the
|
|
// program (if cgo is in use) the list is seeded with a single m.
|
|
// If needm finds that it has taken the last m off the list, its job
|
|
// is - once it has installed its own m so that it can do things like
|
|
// allocate memory - to create a spare m and put it on the list.
|
|
//
|
|
// Each of these extra m's also has a g0 and a curg that are
|
|
// pressed into service as the scheduling stack and current
|
|
// goroutine for the duration of the cgo callback.
|
|
//
|
|
// When the callback is done with the m, it calls dropm to
|
|
// put the m back on the list.
|
|
//
|
|
// Unlike the gc toolchain, we start running on curg, since we are
|
|
// just going to return and let the caller continue.
|
|
void
|
|
runtime_needm(void)
|
|
{
|
|
M *mp;
|
|
|
|
// Lock extra list, take head, unlock popped list.
|
|
// nilokay=false is safe here because of the invariant above,
|
|
// that the extra list always contains or will soon contain
|
|
// at least one m.
|
|
mp = lockextra(false);
|
|
|
|
// Set needextram when we've just emptied the list,
|
|
// so that the eventual call into cgocallbackg will
|
|
// allocate a new m for the extra list. We delay the
|
|
// allocation until then so that it can be done
|
|
// after exitsyscall makes sure it is okay to be
|
|
// running at all (that is, there's no garbage collection
|
|
// running right now).
|
|
mp->needextram = mp->schedlink == nil;
|
|
unlockextra(mp->schedlink);
|
|
|
|
// Install m and g (= m->curg).
|
|
runtime_setmg(mp, mp->curg);
|
|
|
|
// Initialize g's context as in mstart.
|
|
initcontext();
|
|
g->status = Gsyscall;
|
|
g->entry = nil;
|
|
g->param = nil;
|
|
#ifdef USING_SPLIT_STACK
|
|
__splitstack_getcontext(&g->stack_context[0]);
|
|
#else
|
|
g->gcinitial_sp = ∓
|
|
g->gcstack_size = 0;
|
|
g->gcnext_sp = ∓
|
|
#endif
|
|
getcontext(&g->context);
|
|
|
|
if(g->entry != nil) {
|
|
// Got here from mcall.
|
|
void (*pfn)(G*) = (void (*)(G*))g->entry;
|
|
G* gp = (G*)g->param;
|
|
pfn(gp);
|
|
*(int*)0x22 = 0x22;
|
|
}
|
|
|
|
// Initialize this thread to use the m.
|
|
runtime_minit();
|
|
|
|
#ifdef USING_SPLIT_STACK
|
|
{
|
|
int dont_block_signals = 0;
|
|
__splitstack_block_signals(&dont_block_signals, nil);
|
|
}
|
|
#endif
|
|
}
|
|
|
|
// newextram allocates an m and puts it on the extra list.
|
|
// It is called with a working local m, so that it can do things
|
|
// like call schedlock and allocate.
|
|
void
|
|
runtime_newextram(void)
|
|
{
|
|
M *mp, *mnext;
|
|
G *gp;
|
|
byte *g0_sp, *sp;
|
|
size_t g0_spsize, spsize;
|
|
|
|
// Create extra goroutine locked to extra m.
|
|
// The goroutine is the context in which the cgo callback will run.
|
|
// The sched.pc will never be returned to, but setting it to
|
|
// runtime.goexit makes clear to the traceback routines where
|
|
// the goroutine stack ends.
|
|
mp = runtime_allocm(nil, StackMin, &g0_sp, &g0_spsize);
|
|
gp = runtime_malg(StackMin, &sp, &spsize);
|
|
gp->status = Gdead;
|
|
mp->curg = gp;
|
|
mp->locked = LockInternal;
|
|
mp->lockedg = gp;
|
|
gp->lockedm = mp;
|
|
// put on allg for garbage collector
|
|
runtime_lock(&runtime_sched);
|
|
if(runtime_lastg == nil)
|
|
runtime_allg = gp;
|
|
else
|
|
runtime_lastg->alllink = gp;
|
|
runtime_lastg = gp;
|
|
runtime_unlock(&runtime_sched);
|
|
gp->goid = runtime_xadd64(&runtime_sched.goidgen, 1);
|
|
|
|
// The context for gp will be set up in runtime_needm. But
|
|
// here we need to set up the context for g0.
|
|
getcontext(&mp->g0->context);
|
|
mp->g0->context.uc_stack.ss_sp = g0_sp;
|
|
#ifdef MAKECONTEXT_STACK_TOP
|
|
mp->g0->context.uc_stack.ss_sp += g0_spsize;
|
|
#endif
|
|
mp->g0->context.uc_stack.ss_size = g0_spsize;
|
|
makecontext(&mp->g0->context, kickoff, 0);
|
|
|
|
// Add m to the extra list.
|
|
mnext = lockextra(true);
|
|
mp->schedlink = mnext;
|
|
unlockextra(mp);
|
|
}
|
|
|
|
// dropm is called when a cgo callback has called needm but is now
|
|
// done with the callback and returning back into the non-Go thread.
|
|
// It puts the current m back onto the extra list.
|
|
//
|
|
// The main expense here is the call to signalstack to release the
|
|
// m's signal stack, and then the call to needm on the next callback
|
|
// from this thread. It is tempting to try to save the m for next time,
|
|
// which would eliminate both these costs, but there might not be
|
|
// a next time: the current thread (which Go does not control) might exit.
|
|
// If we saved the m for that thread, there would be an m leak each time
|
|
// such a thread exited. Instead, we acquire and release an m on each
|
|
// call. These should typically not be scheduling operations, just a few
|
|
// atomics, so the cost should be small.
|
|
//
|
|
// TODO(rsc): An alternative would be to allocate a dummy pthread per-thread
|
|
// variable using pthread_key_create. Unlike the pthread keys we already use
|
|
// on OS X, this dummy key would never be read by Go code. It would exist
|
|
// only so that we could register at thread-exit-time destructor.
|
|
// That destructor would put the m back onto the extra list.
|
|
// This is purely a performance optimization. The current version,
|
|
// in which dropm happens on each cgo call, is still correct too.
|
|
// We may have to keep the current version on systems with cgo
|
|
// but without pthreads, like Windows.
|
|
void
|
|
runtime_dropm(void)
|
|
{
|
|
M *mp, *mnext;
|
|
|
|
// Undo whatever initialization minit did during needm.
|
|
runtime_unminit();
|
|
|
|
// Clear m and g, and return m to the extra list.
|
|
// After the call to setmg we can only call nosplit functions.
|
|
mp = m;
|
|
runtime_setmg(nil, nil);
|
|
|
|
mp->curg->status = Gdead;
|
|
|
|
mnext = lockextra(true);
|
|
mp->schedlink = mnext;
|
|
unlockextra(mp);
|
|
}
|
|
|
|
#define MLOCKED ((M*)1)
|
|
|
|
// lockextra locks the extra list and returns the list head.
|
|
// The caller must unlock the list by storing a new list head
|
|
// to runtime.extram. If nilokay is true, then lockextra will
|
|
// return a nil list head if that's what it finds. If nilokay is false,
|
|
// lockextra will keep waiting until the list head is no longer nil.
|
|
static M*
|
|
lockextra(bool nilokay)
|
|
{
|
|
M *mp;
|
|
void (*yield)(void);
|
|
|
|
for(;;) {
|
|
mp = runtime_atomicloadp(&runtime_extram);
|
|
if(mp == MLOCKED) {
|
|
yield = runtime_osyield;
|
|
yield();
|
|
continue;
|
|
}
|
|
if(mp == nil && !nilokay) {
|
|
runtime_usleep(1);
|
|
continue;
|
|
}
|
|
if(!runtime_casp(&runtime_extram, mp, MLOCKED)) {
|
|
yield = runtime_osyield;
|
|
yield();
|
|
continue;
|
|
}
|
|
break;
|
|
}
|
|
return mp;
|
|
}
|
|
|
|
static void
|
|
unlockextra(M *mp)
|
|
{
|
|
runtime_atomicstorep(&runtime_extram, mp);
|
|
}
|
|
|
|
static int32
|
|
countextra()
|
|
{
|
|
M *mp, *mc;
|
|
int32 c;
|
|
|
|
for(;;) {
|
|
mp = runtime_atomicloadp(&runtime_extram);
|
|
if(mp == MLOCKED) {
|
|
runtime_osyield();
|
|
continue;
|
|
}
|
|
if(!runtime_casp(&runtime_extram, mp, MLOCKED)) {
|
|
runtime_osyield();
|
|
continue;
|
|
}
|
|
c = 0;
|
|
for(mc = mp; mc != nil; mc = mc->schedlink)
|
|
c++;
|
|
runtime_atomicstorep(&runtime_extram, mp);
|
|
return c;
|
|
}
|
|
}
|
|
|
|
// Create a new m. It will start off with a call to fn, or else the scheduler.
|
|
static void
|
|
newm(void(*fn)(void), P *p)
|
|
{
|
|
M *mp;
|
|
|
|
mp = runtime_allocm(p, -1, nil, nil);
|
|
mp->nextp = p;
|
|
mp->mstartfn = fn;
|
|
|
|
runtime_newosproc(mp);
|
|
}
|
|
|
|
// Stops execution of the current m until new work is available.
|
|
// Returns with acquired P.
|
|
static void
|
|
stopm(void)
|
|
{
|
|
if(m->locks)
|
|
runtime_throw("stopm holding locks");
|
|
if(m->p)
|
|
runtime_throw("stopm holding p");
|
|
if(m->spinning) {
|
|
m->spinning = false;
|
|
runtime_xadd(&runtime_sched.nmspinning, -1);
|
|
}
|
|
|
|
retry:
|
|
runtime_lock(&runtime_sched);
|
|
mput(m);
|
|
runtime_unlock(&runtime_sched);
|
|
runtime_notesleep(&m->park);
|
|
runtime_noteclear(&m->park);
|
|
if(m->helpgc) {
|
|
runtime_gchelper();
|
|
m->helpgc = 0;
|
|
m->mcache = nil;
|
|
goto retry;
|
|
}
|
|
acquirep(m->nextp);
|
|
m->nextp = nil;
|
|
}
|
|
|
|
static void
|
|
mspinning(void)
|
|
{
|
|
m->spinning = true;
|
|
}
|
|
|
|
// Schedules some M to run the p (creates an M if necessary).
|
|
// If p==nil, tries to get an idle P, if no idle P's returns false.
|
|
static void
|
|
startm(P *p, bool spinning)
|
|
{
|
|
M *mp;
|
|
void (*fn)(void);
|
|
|
|
runtime_lock(&runtime_sched);
|
|
if(p == nil) {
|
|
p = pidleget();
|
|
if(p == nil) {
|
|
runtime_unlock(&runtime_sched);
|
|
if(spinning)
|
|
runtime_xadd(&runtime_sched.nmspinning, -1);
|
|
return;
|
|
}
|
|
}
|
|
mp = mget();
|
|
runtime_unlock(&runtime_sched);
|
|
if(mp == nil) {
|
|
fn = nil;
|
|
if(spinning)
|
|
fn = mspinning;
|
|
newm(fn, p);
|
|
return;
|
|
}
|
|
if(mp->spinning)
|
|
runtime_throw("startm: m is spinning");
|
|
if(mp->nextp)
|
|
runtime_throw("startm: m has p");
|
|
mp->spinning = spinning;
|
|
mp->nextp = p;
|
|
runtime_notewakeup(&mp->park);
|
|
}
|
|
|
|
// Hands off P from syscall or locked M.
|
|
static void
|
|
handoffp(P *p)
|
|
{
|
|
// if it has local work, start it straight away
|
|
if(p->runqhead != p->runqtail || runtime_sched.runqsize) {
|
|
startm(p, false);
|
|
return;
|
|
}
|
|
// no local work, check that there are no spinning/idle M's,
|
|
// otherwise our help is not required
|
|
if(runtime_atomicload(&runtime_sched.nmspinning) + runtime_atomicload(&runtime_sched.npidle) == 0 && // TODO: fast atomic
|
|
runtime_cas(&runtime_sched.nmspinning, 0, 1)) {
|
|
startm(p, true);
|
|
return;
|
|
}
|
|
runtime_lock(&runtime_sched);
|
|
if(runtime_gcwaiting) {
|
|
p->status = Pgcstop;
|
|
if(--runtime_sched.stopwait == 0)
|
|
runtime_notewakeup(&runtime_sched.stopnote);
|
|
runtime_unlock(&runtime_sched);
|
|
return;
|
|
}
|
|
if(runtime_sched.runqsize) {
|
|
runtime_unlock(&runtime_sched);
|
|
startm(p, false);
|
|
return;
|
|
}
|
|
// If this is the last running P and nobody is polling network,
|
|
// need to wakeup another M to poll network.
|
|
if(runtime_sched.npidle == (uint32)runtime_gomaxprocs-1 && runtime_atomicload64(&runtime_sched.lastpoll) != 0) {
|
|
runtime_unlock(&runtime_sched);
|
|
startm(p, false);
|
|
return;
|
|
}
|
|
pidleput(p);
|
|
runtime_unlock(&runtime_sched);
|
|
}
|
|
|
|
// Tries to add one more P to execute G's.
|
|
// Called when a G is made runnable (newproc, ready).
|
|
static void
|
|
wakep(void)
|
|
{
|
|
// be conservative about spinning threads
|
|
if(!runtime_cas(&runtime_sched.nmspinning, 0, 1))
|
|
return;
|
|
startm(nil, true);
|
|
}
|
|
|
|
// Stops execution of the current m that is locked to a g until the g is runnable again.
|
|
// Returns with acquired P.
|
|
static void
|
|
stoplockedm(void)
|
|
{
|
|
P *p;
|
|
|
|
if(m->lockedg == nil || m->lockedg->lockedm != m)
|
|
runtime_throw("stoplockedm: inconsistent locking");
|
|
if(m->p) {
|
|
// Schedule another M to run this p.
|
|
p = releasep();
|
|
handoffp(p);
|
|
}
|
|
inclocked(1);
|
|
// Wait until another thread schedules lockedg again.
|
|
runtime_notesleep(&m->park);
|
|
runtime_noteclear(&m->park);
|
|
if(m->lockedg->status != Grunnable)
|
|
runtime_throw("stoplockedm: not runnable");
|
|
acquirep(m->nextp);
|
|
m->nextp = nil;
|
|
}
|
|
|
|
// Schedules the locked m to run the locked gp.
|
|
static void
|
|
startlockedm(G *gp)
|
|
{
|
|
M *mp;
|
|
P *p;
|
|
|
|
mp = gp->lockedm;
|
|
if(mp == m)
|
|
runtime_throw("startlockedm: locked to me");
|
|
if(mp->nextp)
|
|
runtime_throw("startlockedm: m has p");
|
|
// directly handoff current P to the locked m
|
|
inclocked(-1);
|
|
p = releasep();
|
|
mp->nextp = p;
|
|
runtime_notewakeup(&mp->park);
|
|
stopm();
|
|
}
|
|
|
|
// Stops the current m for stoptheworld.
|
|
// Returns when the world is restarted.
|
|
static void
|
|
gcstopm(void)
|
|
{
|
|
P *p;
|
|
|
|
if(!runtime_gcwaiting)
|
|
runtime_throw("gcstopm: not waiting for gc");
|
|
if(m->spinning) {
|
|
m->spinning = false;
|
|
runtime_xadd(&runtime_sched.nmspinning, -1);
|
|
}
|
|
p = releasep();
|
|
runtime_lock(&runtime_sched);
|
|
p->status = Pgcstop;
|
|
if(--runtime_sched.stopwait == 0)
|
|
runtime_notewakeup(&runtime_sched.stopnote);
|
|
runtime_unlock(&runtime_sched);
|
|
stopm();
|
|
}
|
|
|
|
// Schedules gp to run on the current M.
|
|
// Never returns.
|
|
static void
|
|
execute(G *gp)
|
|
{
|
|
int32 hz;
|
|
|
|
if(gp->status != Grunnable) {
|
|
runtime_printf("execute: bad g status %d\n", gp->status);
|
|
runtime_throw("execute: bad g status");
|
|
}
|
|
gp->status = Grunning;
|
|
m->p->tick++;
|
|
m->curg = gp;
|
|
gp->m = m;
|
|
|
|
// Check whether the profiler needs to be turned on or off.
|
|
hz = runtime_sched.profilehz;
|
|
if(m->profilehz != hz)
|
|
runtime_resetcpuprofiler(hz);
|
|
|
|
runtime_gogo(gp);
|
|
}
|
|
|
|
// Finds a runnable goroutine to execute.
|
|
// Tries to steal from other P's, get g from global queue, poll network.
|
|
static G*
|
|
findrunnable(void)
|
|
{
|
|
G *gp;
|
|
P *p;
|
|
int32 i;
|
|
|
|
top:
|
|
if(runtime_gcwaiting) {
|
|
gcstopm();
|
|
goto top;
|
|
}
|
|
// local runq
|
|
gp = runqget(m->p);
|
|
if(gp)
|
|
return gp;
|
|
// global runq
|
|
if(runtime_sched.runqsize) {
|
|
runtime_lock(&runtime_sched);
|
|
gp = globrunqget(m->p);
|
|
runtime_unlock(&runtime_sched);
|
|
if(gp)
|
|
return gp;
|
|
}
|
|
// poll network
|
|
gp = runtime_netpoll(false); // non-blocking
|
|
if(gp) {
|
|
injectglist(gp->schedlink);
|
|
gp->status = Grunnable;
|
|
return gp;
|
|
}
|
|
// If number of spinning M's >= number of busy P's, block.
|
|
// This is necessary to prevent excessive CPU consumption
|
|
// when GOMAXPROCS>>1 but the program parallelism is low.
|
|
if(!m->spinning && 2 * runtime_atomicload(&runtime_sched.nmspinning) >= runtime_gomaxprocs - runtime_atomicload(&runtime_sched.npidle)) // TODO: fast atomic
|
|
goto stop;
|
|
if(!m->spinning) {
|
|
m->spinning = true;
|
|
runtime_xadd(&runtime_sched.nmspinning, 1);
|
|
}
|
|
// random steal from other P's
|
|
for(i = 0; i < 2*runtime_gomaxprocs; i++) {
|
|
if(runtime_gcwaiting)
|
|
goto top;
|
|
p = runtime_allp[runtime_fastrand1()%runtime_gomaxprocs];
|
|
if(p == m->p)
|
|
gp = runqget(p);
|
|
else
|
|
gp = runqsteal(m->p, p);
|
|
if(gp)
|
|
return gp;
|
|
}
|
|
stop:
|
|
// return P and block
|
|
runtime_lock(&runtime_sched);
|
|
if(runtime_gcwaiting) {
|
|
runtime_unlock(&runtime_sched);
|
|
goto top;
|
|
}
|
|
if(runtime_sched.runqsize) {
|
|
gp = globrunqget(m->p);
|
|
runtime_unlock(&runtime_sched);
|
|
return gp;
|
|
}
|
|
p = releasep();
|
|
pidleput(p);
|
|
runtime_unlock(&runtime_sched);
|
|
if(m->spinning) {
|
|
m->spinning = false;
|
|
runtime_xadd(&runtime_sched.nmspinning, -1);
|
|
}
|
|
// check all runqueues once again
|
|
for(i = 0; i < runtime_gomaxprocs; i++) {
|
|
p = runtime_allp[i];
|
|
if(p && p->runqhead != p->runqtail) {
|
|
runtime_lock(&runtime_sched);
|
|
p = pidleget();
|
|
runtime_unlock(&runtime_sched);
|
|
if(p) {
|
|
acquirep(p);
|
|
goto top;
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
// poll network
|
|
if(runtime_xchg64(&runtime_sched.lastpoll, 0) != 0) {
|
|
if(m->p)
|
|
runtime_throw("findrunnable: netpoll with p");
|
|
if(m->spinning)
|
|
runtime_throw("findrunnable: netpoll with spinning");
|
|
gp = runtime_netpoll(true); // block until new work is available
|
|
runtime_atomicstore64(&runtime_sched.lastpoll, runtime_nanotime());
|
|
if(gp) {
|
|
runtime_lock(&runtime_sched);
|
|
p = pidleget();
|
|
runtime_unlock(&runtime_sched);
|
|
if(p) {
|
|
acquirep(p);
|
|
injectglist(gp->schedlink);
|
|
gp->status = Grunnable;
|
|
return gp;
|
|
}
|
|
injectglist(gp);
|
|
}
|
|
}
|
|
stopm();
|
|
goto top;
|
|
}
|
|
|
|
// Injects the list of runnable G's into the scheduler.
|
|
// Can run concurrently with GC.
|
|
static void
|
|
injectglist(G *glist)
|
|
{
|
|
int32 n;
|
|
G *gp;
|
|
|
|
if(glist == nil)
|
|
return;
|
|
runtime_lock(&runtime_sched);
|
|
for(n = 0; glist; n++) {
|
|
gp = glist;
|
|
glist = gp->schedlink;
|
|
gp->status = Grunnable;
|
|
globrunqput(gp);
|
|
}
|
|
runtime_unlock(&runtime_sched);
|
|
|
|
for(; n && runtime_sched.npidle; n--)
|
|
startm(nil, false);
|
|
}
|
|
|
|
// One round of scheduler: find a runnable goroutine and execute it.
|
|
// Never returns.
|
|
static void
|
|
schedule(void)
|
|
{
|
|
G *gp;
|
|
|
|
if(m->locks)
|
|
runtime_throw("schedule: holding locks");
|
|
|
|
top:
|
|
if(runtime_gcwaiting) {
|
|
gcstopm();
|
|
goto top;
|
|
}
|
|
|
|
gp = runqget(m->p);
|
|
if(gp == nil)
|
|
gp = findrunnable();
|
|
|
|
if(m->spinning) {
|
|
m->spinning = false;
|
|
runtime_xadd(&runtime_sched.nmspinning, -1);
|
|
}
|
|
|
|
// M wakeup policy is deliberately somewhat conservative (see nmspinning handling),
|
|
// so see if we need to wakeup another M here.
|
|
if (m->p->runqhead != m->p->runqtail &&
|
|
runtime_atomicload(&runtime_sched.nmspinning) == 0 &&
|
|
runtime_atomicload(&runtime_sched.npidle) > 0) // TODO: fast atomic
|
|
wakep();
|
|
|
|
if(gp->lockedm) {
|
|
startlockedm(gp);
|
|
goto top;
|
|
}
|
|
|
|
execute(gp);
|
|
}
|
|
|
|
// Puts the current goroutine into a waiting state and unlocks the lock.
|
|
// The goroutine can be made runnable again by calling runtime_ready(gp).
|
|
void
|
|
runtime_park(void(*unlockf)(Lock*), Lock *lock, const char *reason)
|
|
{
|
|
m->waitlock = lock;
|
|
m->waitunlockf = unlockf;
|
|
g->waitreason = reason;
|
|
runtime_mcall(park0);
|
|
}
|
|
|
|
// runtime_park continuation on g0.
|
|
static void
|
|
park0(G *gp)
|
|
{
|
|
gp->status = Gwaiting;
|
|
gp->m = nil;
|
|
m->curg = nil;
|
|
if(m->waitunlockf) {
|
|
m->waitunlockf(m->waitlock);
|
|
m->waitunlockf = nil;
|
|
m->waitlock = nil;
|
|
}
|
|
if(m->lockedg) {
|
|
stoplockedm();
|
|
execute(gp); // Never returns.
|
|
}
|
|
schedule();
|
|
}
|
|
|
|
// Scheduler yield.
|
|
void
|
|
runtime_gosched(void)
|
|
{
|
|
runtime_mcall(gosched0);
|
|
}
|
|
|
|
// runtime_gosched continuation on g0.
|
|
static void
|
|
gosched0(G *gp)
|
|
{
|
|
gp->status = Grunnable;
|
|
gp->m = nil;
|
|
m->curg = nil;
|
|
runtime_lock(&runtime_sched);
|
|
globrunqput(gp);
|
|
runtime_unlock(&runtime_sched);
|
|
if(m->lockedg) {
|
|
stoplockedm();
|
|
execute(gp); // Never returns.
|
|
}
|
|
schedule();
|
|
}
|
|
|
|
// Finishes execution of the current goroutine.
|
|
void
|
|
runtime_goexit(void)
|
|
{
|
|
if(raceenabled)
|
|
runtime_racegoend();
|
|
runtime_mcall(goexit0);
|
|
}
|
|
|
|
// runtime_goexit continuation on g0.
|
|
static void
|
|
goexit0(G *gp)
|
|
{
|
|
gp->status = Gdead;
|
|
gp->entry = nil;
|
|
gp->m = nil;
|
|
gp->lockedm = nil;
|
|
m->curg = nil;
|
|
m->lockedg = nil;
|
|
if(m->locked & ~LockExternal) {
|
|
runtime_printf("invalid m->locked = %d", m->locked);
|
|
runtime_throw("internal lockOSThread error");
|
|
}
|
|
m->locked = 0;
|
|
gfput(m->p, gp);
|
|
schedule();
|
|
}
|
|
|
|
// The goroutine g is about to enter a system call.
|
|
// Record that it's not using the cpu anymore.
|
|
// This is called only from the go syscall library and cgocall,
|
|
// not from the low-level system calls used by the runtime.
|
|
//
|
|
// Entersyscall cannot split the stack: the runtime_gosave must
|
|
// make g->sched refer to the caller's stack segment, because
|
|
// entersyscall is going to return immediately after.
|
|
|
|
void runtime_entersyscall(void) __attribute__ ((no_split_stack));
|
|
|
|
void
|
|
runtime_entersyscall()
|
|
{
|
|
if(m->profilehz > 0)
|
|
runtime_setprof(false);
|
|
|
|
// Leave SP around for gc and traceback.
|
|
#ifdef USING_SPLIT_STACK
|
|
g->gcstack = __splitstack_find(nil, nil, &g->gcstack_size,
|
|
&g->gcnext_segment, &g->gcnext_sp,
|
|
&g->gcinitial_sp);
|
|
#else
|
|
{
|
|
uint32 v;
|
|
|
|
g->gcnext_sp = (byte *) &v;
|
|
}
|
|
#endif
|
|
|
|
// Save the registers in the g structure so that any pointers
|
|
// held in registers will be seen by the garbage collector.
|
|
getcontext(&g->gcregs);
|
|
|
|
g->status = Gsyscall;
|
|
|
|
if(runtime_atomicload(&runtime_sched.sysmonwait)) { // TODO: fast atomic
|
|
runtime_lock(&runtime_sched);
|
|
if(runtime_atomicload(&runtime_sched.sysmonwait)) {
|
|
runtime_atomicstore(&runtime_sched.sysmonwait, 0);
|
|
runtime_notewakeup(&runtime_sched.sysmonnote);
|
|
}
|
|
runtime_unlock(&runtime_sched);
|
|
}
|
|
|
|
m->mcache = nil;
|
|
m->p->tick++;
|
|
m->p->m = nil;
|
|
runtime_atomicstore(&m->p->status, Psyscall);
|
|
if(runtime_gcwaiting) {
|
|
runtime_lock(&runtime_sched);
|
|
if (runtime_sched.stopwait > 0 && runtime_cas(&m->p->status, Psyscall, Pgcstop)) {
|
|
if(--runtime_sched.stopwait == 0)
|
|
runtime_notewakeup(&runtime_sched.stopnote);
|
|
}
|
|
runtime_unlock(&runtime_sched);
|
|
}
|
|
}
|
|
|
|
// The same as runtime_entersyscall(), but with a hint that the syscall is blocking.
|
|
void
|
|
runtime_entersyscallblock(void)
|
|
{
|
|
P *p;
|
|
|
|
if(m->profilehz > 0)
|
|
runtime_setprof(false);
|
|
|
|
// Leave SP around for gc and traceback.
|
|
#ifdef USING_SPLIT_STACK
|
|
g->gcstack = __splitstack_find(nil, nil, &g->gcstack_size,
|
|
&g->gcnext_segment, &g->gcnext_sp,
|
|
&g->gcinitial_sp);
|
|
#else
|
|
g->gcnext_sp = (byte *) &p;
|
|
#endif
|
|
|
|
// Save the registers in the g structure so that any pointers
|
|
// held in registers will be seen by the garbage collector.
|
|
getcontext(&g->gcregs);
|
|
|
|
g->status = Gsyscall;
|
|
|
|
p = releasep();
|
|
handoffp(p);
|
|
if(g->isbackground) // do not consider blocked scavenger for deadlock detection
|
|
inclocked(1);
|
|
}
|
|
|
|
// The goroutine g exited its system call.
|
|
// Arrange for it to run on a cpu again.
|
|
// This is called only from the go syscall library, not
|
|
// from the low-level system calls used by the runtime.
|
|
void
|
|
runtime_exitsyscall(void)
|
|
{
|
|
G *gp;
|
|
P *p;
|
|
|
|
// Check whether the profiler needs to be turned on.
|
|
if(m->profilehz > 0)
|
|
runtime_setprof(true);
|
|
|
|
gp = g;
|
|
// Try to re-acquire the last P.
|
|
if(m->p && m->p->status == Psyscall && runtime_cas(&m->p->status, Psyscall, Prunning)) {
|
|
// There's a cpu for us, so we can run.
|
|
m->mcache = m->p->mcache;
|
|
m->p->m = m;
|
|
m->p->tick++;
|
|
gp->status = Grunning;
|
|
// Garbage collector isn't running (since we are),
|
|
// so okay to clear gcstack and gcsp.
|
|
#ifdef USING_SPLIT_STACK
|
|
gp->gcstack = nil;
|
|
#endif
|
|
gp->gcnext_sp = nil;
|
|
runtime_memclr(&gp->gcregs, sizeof gp->gcregs);
|
|
return;
|
|
}
|
|
|
|
if(gp->isbackground) // do not consider blocked scavenger for deadlock detection
|
|
inclocked(-1);
|
|
// Try to get any other idle P.
|
|
m->p = nil;
|
|
if(runtime_sched.pidle) {
|
|
runtime_lock(&runtime_sched);
|
|
p = pidleget();
|
|
runtime_unlock(&runtime_sched);
|
|
if(p) {
|
|
acquirep(p);
|
|
#ifdef USING_SPLIT_STACK
|
|
gp->gcstack = nil;
|
|
#endif
|
|
gp->gcnext_sp = nil;
|
|
runtime_memclr(&gp->gcregs, sizeof gp->gcregs);
|
|
return;
|
|
}
|
|
}
|
|
|
|
// Call the scheduler.
|
|
runtime_mcall(exitsyscall0);
|
|
|
|
// Scheduler returned, so we're allowed to run now.
|
|
// Delete the gcstack information that we left for
|
|
// the garbage collector during the system call.
|
|
// Must wait until now because until gosched returns
|
|
// we don't know for sure that the garbage collector
|
|
// is not running.
|
|
#ifdef USING_SPLIT_STACK
|
|
gp->gcstack = nil;
|
|
#endif
|
|
gp->gcnext_sp = nil;
|
|
runtime_memclr(&gp->gcregs, sizeof gp->gcregs);
|
|
}
|
|
|
|
// runtime_exitsyscall slow path on g0.
|
|
// Failed to acquire P, enqueue gp as runnable.
|
|
static void
|
|
exitsyscall0(G *gp)
|
|
{
|
|
P *p;
|
|
|
|
gp->status = Grunnable;
|
|
gp->m = nil;
|
|
m->curg = nil;
|
|
runtime_lock(&runtime_sched);
|
|
p = pidleget();
|
|
if(p == nil)
|
|
globrunqput(gp);
|
|
runtime_unlock(&runtime_sched);
|
|
if(p) {
|
|
acquirep(p);
|
|
execute(gp); // Never returns.
|
|
}
|
|
if(m->lockedg) {
|
|
// Wait until another thread schedules gp and so m again.
|
|
stoplockedm();
|
|
execute(gp); // Never returns.
|
|
}
|
|
stopm();
|
|
schedule(); // Never returns.
|
|
}
|
|
|
|
// Allocate a new g, with a stack big enough for stacksize bytes.
|
|
G*
|
|
runtime_malg(int32 stacksize, byte** ret_stack, size_t* ret_stacksize)
|
|
{
|
|
G *newg;
|
|
|
|
newg = runtime_malloc(sizeof(G));
|
|
if(stacksize >= 0) {
|
|
#if USING_SPLIT_STACK
|
|
int dont_block_signals = 0;
|
|
|
|
*ret_stack = __splitstack_makecontext(stacksize,
|
|
&newg->stack_context[0],
|
|
ret_stacksize);
|
|
__splitstack_block_signals_context(&newg->stack_context[0],
|
|
&dont_block_signals, nil);
|
|
#else
|
|
*ret_stack = runtime_mallocgc(stacksize, FlagNoProfiling|FlagNoGC, 0, 0);
|
|
*ret_stacksize = stacksize;
|
|
newg->gcinitial_sp = *ret_stack;
|
|
newg->gcstack_size = stacksize;
|
|
runtime_xadd(&runtime_stacks_sys, stacksize);
|
|
#endif
|
|
}
|
|
return newg;
|
|
}
|
|
|
|
/* For runtime package testing. */
|
|
|
|
void runtime_testing_entersyscall(void)
|
|
__asm__ (GOSYM_PREFIX "runtime.entersyscall");
|
|
|
|
void
|
|
runtime_testing_entersyscall()
|
|
{
|
|
runtime_entersyscall();
|
|
}
|
|
|
|
void runtime_testing_exitsyscall(void)
|
|
__asm__ (GOSYM_PREFIX "runtime.exitsyscall");
|
|
|
|
void
|
|
runtime_testing_exitsyscall()
|
|
{
|
|
runtime_exitsyscall();
|
|
}
|
|
|
|
G*
|
|
__go_go(void (*fn)(void*), void* arg)
|
|
{
|
|
byte *sp;
|
|
size_t spsize;
|
|
G *newg;
|
|
|
|
m->locks++; // disable preemption because it can be holding p in a local var
|
|
|
|
if((newg = gfget(m->p)) != nil) {
|
|
#ifdef USING_SPLIT_STACK
|
|
int dont_block_signals = 0;
|
|
|
|
sp = __splitstack_resetcontext(&newg->stack_context[0],
|
|
&spsize);
|
|
__splitstack_block_signals_context(&newg->stack_context[0],
|
|
&dont_block_signals, nil);
|
|
#else
|
|
sp = newg->gcinitial_sp;
|
|
spsize = newg->gcstack_size;
|
|
if(spsize == 0)
|
|
runtime_throw("bad spsize in __go_go");
|
|
newg->gcnext_sp = sp;
|
|
#endif
|
|
} else {
|
|
newg = runtime_malg(StackMin, &sp, &spsize);
|
|
runtime_lock(&runtime_sched);
|
|
if(runtime_lastg == nil)
|
|
runtime_allg = newg;
|
|
else
|
|
runtime_lastg->alllink = newg;
|
|
runtime_lastg = newg;
|
|
runtime_unlock(&runtime_sched);
|
|
}
|
|
|
|
newg->entry = (byte*)fn;
|
|
newg->param = arg;
|
|
newg->gopc = (uintptr)__builtin_return_address(0);
|
|
newg->status = Grunnable;
|
|
newg->goid = runtime_xadd64(&runtime_sched.goidgen, 1);
|
|
|
|
{
|
|
// Avoid warnings about variables clobbered by
|
|
// longjmp.
|
|
byte * volatile vsp = sp;
|
|
size_t volatile vspsize = spsize;
|
|
G * volatile vnewg = newg;
|
|
|
|
getcontext(&vnewg->context);
|
|
vnewg->context.uc_stack.ss_sp = vsp;
|
|
#ifdef MAKECONTEXT_STACK_TOP
|
|
vnewg->context.uc_stack.ss_sp += vspsize;
|
|
#endif
|
|
vnewg->context.uc_stack.ss_size = vspsize;
|
|
makecontext(&vnewg->context, kickoff, 0);
|
|
|
|
runqput(m->p, vnewg);
|
|
|
|
if(runtime_atomicload(&runtime_sched.npidle) != 0 && runtime_atomicload(&runtime_sched.nmspinning) == 0 && fn != runtime_main) // TODO: fast atomic
|
|
wakep();
|
|
m->locks--;
|
|
return vnewg;
|
|
}
|
|
}
|
|
|
|
// Put on gfree list.
|
|
// If local list is too long, transfer a batch to the global list.
|
|
static void
|
|
gfput(P *p, G *gp)
|
|
{
|
|
gp->schedlink = p->gfree;
|
|
p->gfree = gp;
|
|
p->gfreecnt++;
|
|
if(p->gfreecnt >= 64) {
|
|
runtime_lock(&runtime_sched.gflock);
|
|
while(p->gfreecnt >= 32) {
|
|
p->gfreecnt--;
|
|
gp = p->gfree;
|
|
p->gfree = gp->schedlink;
|
|
gp->schedlink = runtime_sched.gfree;
|
|
runtime_sched.gfree = gp;
|
|
}
|
|
runtime_unlock(&runtime_sched.gflock);
|
|
}
|
|
}
|
|
|
|
// Get from gfree list.
|
|
// If local list is empty, grab a batch from global list.
|
|
static G*
|
|
gfget(P *p)
|
|
{
|
|
G *gp;
|
|
|
|
retry:
|
|
gp = p->gfree;
|
|
if(gp == nil && runtime_sched.gfree) {
|
|
runtime_lock(&runtime_sched.gflock);
|
|
while(p->gfreecnt < 32 && runtime_sched.gfree) {
|
|
p->gfreecnt++;
|
|
gp = runtime_sched.gfree;
|
|
runtime_sched.gfree = gp->schedlink;
|
|
gp->schedlink = p->gfree;
|
|
p->gfree = gp;
|
|
}
|
|
runtime_unlock(&runtime_sched.gflock);
|
|
goto retry;
|
|
}
|
|
if(gp) {
|
|
p->gfree = gp->schedlink;
|
|
p->gfreecnt--;
|
|
}
|
|
return gp;
|
|
}
|
|
|
|
// Purge all cached G's from gfree list to the global list.
|
|
static void
|
|
gfpurge(P *p)
|
|
{
|
|
G *gp;
|
|
|
|
runtime_lock(&runtime_sched.gflock);
|
|
while(p->gfreecnt) {
|
|
p->gfreecnt--;
|
|
gp = p->gfree;
|
|
p->gfree = gp->schedlink;
|
|
gp->schedlink = runtime_sched.gfree;
|
|
runtime_sched.gfree = gp;
|
|
}
|
|
runtime_unlock(&runtime_sched.gflock);
|
|
}
|
|
|
|
void
|
|
runtime_Breakpoint(void)
|
|
{
|
|
runtime_breakpoint();
|
|
}
|
|
|
|
void runtime_Gosched (void) __asm__ (GOSYM_PREFIX "runtime.Gosched");
|
|
|
|
void
|
|
runtime_Gosched(void)
|
|
{
|
|
runtime_gosched();
|
|
}
|
|
|
|
// Implementation of runtime.GOMAXPROCS.
|
|
// delete when scheduler is even stronger
|
|
int32
|
|
runtime_gomaxprocsfunc(int32 n)
|
|
{
|
|
int32 ret;
|
|
|
|
if(n > MaxGomaxprocs)
|
|
n = MaxGomaxprocs;
|
|
runtime_lock(&runtime_sched);
|
|
ret = runtime_gomaxprocs;
|
|
if(n <= 0 || n == ret) {
|
|
runtime_unlock(&runtime_sched);
|
|
return ret;
|
|
}
|
|
runtime_unlock(&runtime_sched);
|
|
|
|
runtime_semacquire(&runtime_worldsema);
|
|
m->gcing = 1;
|
|
runtime_stoptheworld();
|
|
newprocs = n;
|
|
m->gcing = 0;
|
|
runtime_semrelease(&runtime_worldsema);
|
|
runtime_starttheworld();
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void
|
|
LockOSThread(void)
|
|
{
|
|
m->lockedg = g;
|
|
g->lockedm = m;
|
|
}
|
|
|
|
void runtime_LockOSThread(void) __asm__ (GOSYM_PREFIX "runtime.LockOSThread");
|
|
void
|
|
runtime_LockOSThread(void)
|
|
{
|
|
m->locked |= LockExternal;
|
|
LockOSThread();
|
|
}
|
|
|
|
void
|
|
runtime_lockOSThread(void)
|
|
{
|
|
m->locked += LockInternal;
|
|
LockOSThread();
|
|
}
|
|
|
|
static void
|
|
UnlockOSThread(void)
|
|
{
|
|
if(m->locked != 0)
|
|
return;
|
|
m->lockedg = nil;
|
|
g->lockedm = nil;
|
|
}
|
|
|
|
void runtime_UnlockOSThread(void) __asm__ (GOSYM_PREFIX "runtime.UnlockOSThread");
|
|
|
|
void
|
|
runtime_UnlockOSThread(void)
|
|
{
|
|
m->locked &= ~LockExternal;
|
|
UnlockOSThread();
|
|
}
|
|
|
|
void
|
|
runtime_unlockOSThread(void)
|
|
{
|
|
if(m->locked < LockInternal)
|
|
runtime_throw("runtime: internal error: misuse of lockOSThread/unlockOSThread");
|
|
m->locked -= LockInternal;
|
|
UnlockOSThread();
|
|
}
|
|
|
|
bool
|
|
runtime_lockedOSThread(void)
|
|
{
|
|
return g->lockedm != nil && m->lockedg != nil;
|
|
}
|
|
|
|
// for testing of callbacks
|
|
|
|
_Bool runtime_golockedOSThread(void)
|
|
__asm__ (GOSYM_PREFIX "runtime.golockedOSThread");
|
|
|
|
_Bool
|
|
runtime_golockedOSThread(void)
|
|
{
|
|
return runtime_lockedOSThread();
|
|
}
|
|
|
|
// for testing of wire, unwire
|
|
uint32
|
|
runtime_mid()
|
|
{
|
|
return m->id;
|
|
}
|
|
|
|
intgo runtime_NumGoroutine (void)
|
|
__asm__ (GOSYM_PREFIX "runtime.NumGoroutine");
|
|
|
|
intgo
|
|
runtime_NumGoroutine()
|
|
{
|
|
return runtime_gcount();
|
|
}
|
|
|
|
int32
|
|
runtime_gcount(void)
|
|
{
|
|
G *gp;
|
|
int32 n, s;
|
|
|
|
n = 0;
|
|
runtime_lock(&runtime_sched);
|
|
// TODO(dvyukov): runtime.NumGoroutine() is O(N).
|
|
// We do not want to increment/decrement centralized counter in newproc/goexit,
|
|
// just to make runtime.NumGoroutine() faster.
|
|
// Compromise solution is to introduce per-P counters of active goroutines.
|
|
for(gp = runtime_allg; gp; gp = gp->alllink) {
|
|
s = gp->status;
|
|
if(s == Grunnable || s == Grunning || s == Gsyscall || s == Gwaiting)
|
|
n++;
|
|
}
|
|
runtime_unlock(&runtime_sched);
|
|
return n;
|
|
}
|
|
|
|
int32
|
|
runtime_mcount(void)
|
|
{
|
|
return runtime_sched.mcount;
|
|
}
|
|
|
|
static struct {
|
|
Lock;
|
|
void (*fn)(uintptr*, int32);
|
|
int32 hz;
|
|
uintptr pcbuf[100];
|
|
Location locbuf[100];
|
|
} prof;
|
|
|
|
// Called if we receive a SIGPROF signal.
|
|
void
|
|
runtime_sigprof()
|
|
{
|
|
int32 n, i;
|
|
|
|
// Windows does profiling in a dedicated thread w/o m.
|
|
if(!Windows && (m == nil || m->mcache == nil))
|
|
return;
|
|
if(prof.fn == nil || prof.hz == 0)
|
|
return;
|
|
|
|
runtime_lock(&prof);
|
|
if(prof.fn == nil) {
|
|
runtime_unlock(&prof);
|
|
return;
|
|
}
|
|
n = runtime_callers(0, prof.locbuf, nelem(prof.locbuf));
|
|
for(i = 0; i < n; i++)
|
|
prof.pcbuf[i] = prof.locbuf[i].pc;
|
|
if(n > 0)
|
|
prof.fn(prof.pcbuf, n);
|
|
runtime_unlock(&prof);
|
|
}
|
|
|
|
// Arrange to call fn with a traceback hz times a second.
|
|
void
|
|
runtime_setcpuprofilerate(void (*fn)(uintptr*, int32), int32 hz)
|
|
{
|
|
// Force sane arguments.
|
|
if(hz < 0)
|
|
hz = 0;
|
|
if(hz == 0)
|
|
fn = nil;
|
|
if(fn == nil)
|
|
hz = 0;
|
|
|
|
// Stop profiler on this cpu so that it is safe to lock prof.
|
|
// if a profiling signal came in while we had prof locked,
|
|
// it would deadlock.
|
|
runtime_resetcpuprofiler(0);
|
|
|
|
runtime_lock(&prof);
|
|
prof.fn = fn;
|
|
prof.hz = hz;
|
|
runtime_unlock(&prof);
|
|
runtime_lock(&runtime_sched);
|
|
runtime_sched.profilehz = hz;
|
|
runtime_unlock(&runtime_sched);
|
|
|
|
if(hz != 0)
|
|
runtime_resetcpuprofiler(hz);
|
|
}
|
|
|
|
// Change number of processors. The world is stopped, sched is locked.
|
|
static void
|
|
procresize(int32 new)
|
|
{
|
|
int32 i, old;
|
|
G *gp;
|
|
P *p;
|
|
|
|
old = runtime_gomaxprocs;
|
|
if(old < 0 || old > MaxGomaxprocs || new <= 0 || new >MaxGomaxprocs)
|
|
runtime_throw("procresize: invalid arg");
|
|
// initialize new P's
|
|
for(i = 0; i < new; i++) {
|
|
p = runtime_allp[i];
|
|
if(p == nil) {
|
|
p = (P*)runtime_mallocgc(sizeof(*p), 0, 0, 1);
|
|
p->status = Pgcstop;
|
|
runtime_atomicstorep(&runtime_allp[i], p);
|
|
}
|
|
if(p->mcache == nil) {
|
|
if(old==0 && i==0)
|
|
p->mcache = m->mcache; // bootstrap
|
|
else
|
|
p->mcache = runtime_allocmcache();
|
|
}
|
|
if(p->runq == nil) {
|
|
p->runqsize = 128;
|
|
p->runq = (G**)runtime_mallocgc(p->runqsize*sizeof(G*), 0, 0, 1);
|
|
}
|
|
}
|
|
|
|
// redistribute runnable G's evenly
|
|
for(i = 0; i < old; i++) {
|
|
p = runtime_allp[i];
|
|
while((gp = runqget(p)) != nil)
|
|
globrunqput(gp);
|
|
}
|
|
// start at 1 because current M already executes some G and will acquire allp[0] below,
|
|
// so if we have a spare G we want to put it into allp[1].
|
|
for(i = 1; runtime_sched.runqhead; i++) {
|
|
gp = runtime_sched.runqhead;
|
|
runtime_sched.runqhead = gp->schedlink;
|
|
runqput(runtime_allp[i%new], gp);
|
|
}
|
|
runtime_sched.runqtail = nil;
|
|
runtime_sched.runqsize = 0;
|
|
|
|
// free unused P's
|
|
for(i = new; i < old; i++) {
|
|
p = runtime_allp[i];
|
|
runtime_freemcache(p->mcache);
|
|
p->mcache = nil;
|
|
gfpurge(p);
|
|
p->status = Pdead;
|
|
// can't free P itself because it can be referenced by an M in syscall
|
|
}
|
|
|
|
if(m->p)
|
|
m->p->m = nil;
|
|
m->p = nil;
|
|
m->mcache = nil;
|
|
p = runtime_allp[0];
|
|
p->m = nil;
|
|
p->status = Pidle;
|
|
acquirep(p);
|
|
for(i = new-1; i > 0; i--) {
|
|
p = runtime_allp[i];
|
|
p->status = Pidle;
|
|
pidleput(p);
|
|
}
|
|
runtime_singleproc = new == 1;
|
|
runtime_atomicstore((uint32*)&runtime_gomaxprocs, new);
|
|
}
|
|
|
|
// Associate p and the current m.
|
|
static void
|
|
acquirep(P *p)
|
|
{
|
|
if(m->p || m->mcache)
|
|
runtime_throw("acquirep: already in go");
|
|
if(p->m || p->status != Pidle) {
|
|
runtime_printf("acquirep: p->m=%p(%d) p->status=%d\n", p->m, p->m ? p->m->id : 0, p->status);
|
|
runtime_throw("acquirep: invalid p state");
|
|
}
|
|
m->mcache = p->mcache;
|
|
m->p = p;
|
|
p->m = m;
|
|
p->status = Prunning;
|
|
}
|
|
|
|
// Disassociate p and the current m.
|
|
static P*
|
|
releasep(void)
|
|
{
|
|
P *p;
|
|
|
|
if(m->p == nil || m->mcache == nil)
|
|
runtime_throw("releasep: invalid arg");
|
|
p = m->p;
|
|
if(p->m != m || p->mcache != m->mcache || p->status != Prunning) {
|
|
runtime_printf("releasep: m=%p m->p=%p p->m=%p m->mcache=%p p->mcache=%p p->status=%d\n",
|
|
m, m->p, p->m, m->mcache, p->mcache, p->status);
|
|
runtime_throw("releasep: invalid p state");
|
|
}
|
|
m->p = nil;
|
|
m->mcache = nil;
|
|
p->m = nil;
|
|
p->status = Pidle;
|
|
return p;
|
|
}
|
|
|
|
static void
|
|
inclocked(int32 v)
|
|
{
|
|
runtime_lock(&runtime_sched);
|
|
runtime_sched.mlocked += v;
|
|
if(v > 0)
|
|
checkdead();
|
|
runtime_unlock(&runtime_sched);
|
|
}
|
|
|
|
// Check for deadlock situation.
|
|
// The check is based on number of running M's, if 0 -> deadlock.
|
|
static void
|
|
checkdead(void)
|
|
{
|
|
G *gp;
|
|
int32 run, grunning, s;
|
|
|
|
// -1 for sysmon
|
|
run = runtime_sched.mcount - runtime_sched.nmidle - runtime_sched.mlocked - 1 - countextra();
|
|
if(run > 0)
|
|
return;
|
|
if(run < 0) {
|
|
runtime_printf("checkdead: nmidle=%d mlocked=%d mcount=%d\n",
|
|
runtime_sched.nmidle, runtime_sched.mlocked, runtime_sched.mcount);
|
|
runtime_throw("checkdead: inconsistent counts");
|
|
}
|
|
grunning = 0;
|
|
for(gp = runtime_allg; gp; gp = gp->alllink) {
|
|
if(gp->isbackground)
|
|
continue;
|
|
s = gp->status;
|
|
if(s == Gwaiting)
|
|
grunning++;
|
|
else if(s == Grunnable || s == Grunning || s == Gsyscall) {
|
|
runtime_printf("checkdead: find g %D in status %d\n", gp->goid, s);
|
|
runtime_throw("checkdead: runnable g");
|
|
}
|
|
}
|
|
if(grunning == 0) // possible if main goroutine calls runtime_Goexit()
|
|
runtime_exit(0);
|
|
m->throwing = -1; // do not dump full stacks
|
|
runtime_throw("all goroutines are asleep - deadlock!");
|
|
}
|
|
|
|
static void
|
|
sysmon(void)
|
|
{
|
|
uint32 idle, delay;
|
|
int64 now, lastpoll;
|
|
G *gp;
|
|
uint32 ticks[MaxGomaxprocs];
|
|
|
|
idle = 0; // how many cycles in succession we had not wokeup somebody
|
|
delay = 0;
|
|
for(;;) {
|
|
if(idle == 0) // start with 20us sleep...
|
|
delay = 20;
|
|
else if(idle > 50) // start doubling the sleep after 1ms...
|
|
delay *= 2;
|
|
if(delay > 10*1000) // up to 10ms
|
|
delay = 10*1000;
|
|
runtime_usleep(delay);
|
|
if(runtime_gcwaiting || runtime_atomicload(&runtime_sched.npidle) == (uint32)runtime_gomaxprocs) { // TODO: fast atomic
|
|
runtime_lock(&runtime_sched);
|
|
if(runtime_atomicload(&runtime_gcwaiting) || runtime_atomicload(&runtime_sched.npidle) == (uint32)runtime_gomaxprocs) {
|
|
runtime_atomicstore(&runtime_sched.sysmonwait, 1);
|
|
runtime_unlock(&runtime_sched);
|
|
runtime_notesleep(&runtime_sched.sysmonnote);
|
|
runtime_noteclear(&runtime_sched.sysmonnote);
|
|
idle = 0;
|
|
delay = 20;
|
|
} else
|
|
runtime_unlock(&runtime_sched);
|
|
}
|
|
// poll network if not polled for more than 10ms
|
|
lastpoll = runtime_atomicload64(&runtime_sched.lastpoll);
|
|
now = runtime_nanotime();
|
|
if(lastpoll != 0 && lastpoll + 10*1000*1000 > now) {
|
|
gp = runtime_netpoll(false); // non-blocking
|
|
injectglist(gp);
|
|
}
|
|
// retake P's blocked in syscalls
|
|
if(retake(ticks))
|
|
idle = 0;
|
|
else
|
|
idle++;
|
|
}
|
|
}
|
|
|
|
static uint32
|
|
retake(uint32 *ticks)
|
|
{
|
|
uint32 i, s, n;
|
|
int64 t;
|
|
P *p;
|
|
|
|
n = 0;
|
|
for(i = 0; i < (uint32)runtime_gomaxprocs; i++) {
|
|
p = runtime_allp[i];
|
|
if(p==nil)
|
|
continue;
|
|
t = p->tick;
|
|
if(ticks[i] != t) {
|
|
ticks[i] = t;
|
|
continue;
|
|
}
|
|
s = p->status;
|
|
if(s != Psyscall)
|
|
continue;
|
|
if(p->runqhead == p->runqtail && runtime_atomicload(&runtime_sched.nmspinning) + runtime_atomicload(&runtime_sched.npidle) > 0) // TODO: fast atomic
|
|
continue;
|
|
// Need to increment number of locked M's before the CAS.
|
|
// Otherwise the M from which we retake can exit the syscall,
|
|
// increment nmidle and report deadlock.
|
|
inclocked(-1);
|
|
if(runtime_cas(&p->status, s, Pidle)) {
|
|
n++;
|
|
handoffp(p);
|
|
}
|
|
inclocked(1);
|
|
}
|
|
return n;
|
|
}
|
|
|
|
// Put mp on midle list.
|
|
// Sched must be locked.
|
|
static void
|
|
mput(M *mp)
|
|
{
|
|
mp->schedlink = runtime_sched.midle;
|
|
runtime_sched.midle = mp;
|
|
runtime_sched.nmidle++;
|
|
checkdead();
|
|
}
|
|
|
|
// Try to get an m from midle list.
|
|
// Sched must be locked.
|
|
static M*
|
|
mget(void)
|
|
{
|
|
M *mp;
|
|
|
|
if((mp = runtime_sched.midle) != nil){
|
|
runtime_sched.midle = mp->schedlink;
|
|
runtime_sched.nmidle--;
|
|
}
|
|
return mp;
|
|
}
|
|
|
|
// Put gp on the global runnable queue.
|
|
// Sched must be locked.
|
|
static void
|
|
globrunqput(G *gp)
|
|
{
|
|
gp->schedlink = nil;
|
|
if(runtime_sched.runqtail)
|
|
runtime_sched.runqtail->schedlink = gp;
|
|
else
|
|
runtime_sched.runqhead = gp;
|
|
runtime_sched.runqtail = gp;
|
|
runtime_sched.runqsize++;
|
|
}
|
|
|
|
// Try get a batch of G's from the global runnable queue.
|
|
// Sched must be locked.
|
|
static G*
|
|
globrunqget(P *p)
|
|
{
|
|
G *gp, *gp1;
|
|
int32 n;
|
|
|
|
if(runtime_sched.runqsize == 0)
|
|
return nil;
|
|
n = runtime_sched.runqsize/runtime_gomaxprocs+1;
|
|
if(n > runtime_sched.runqsize)
|
|
n = runtime_sched.runqsize;
|
|
runtime_sched.runqsize -= n;
|
|
if(runtime_sched.runqsize == 0)
|
|
runtime_sched.runqtail = nil;
|
|
gp = runtime_sched.runqhead;
|
|
runtime_sched.runqhead = gp->schedlink;
|
|
n--;
|
|
while(n--) {
|
|
gp1 = runtime_sched.runqhead;
|
|
runtime_sched.runqhead = gp1->schedlink;
|
|
runqput(p, gp1);
|
|
}
|
|
return gp;
|
|
}
|
|
|
|
// Put p to on pidle list.
|
|
// Sched must be locked.
|
|
static void
|
|
pidleput(P *p)
|
|
{
|
|
p->link = runtime_sched.pidle;
|
|
runtime_sched.pidle = p;
|
|
runtime_xadd(&runtime_sched.npidle, 1); // TODO: fast atomic
|
|
}
|
|
|
|
// Try get a p from pidle list.
|
|
// Sched must be locked.
|
|
static P*
|
|
pidleget(void)
|
|
{
|
|
P *p;
|
|
|
|
p = runtime_sched.pidle;
|
|
if(p) {
|
|
runtime_sched.pidle = p->link;
|
|
runtime_xadd(&runtime_sched.npidle, -1); // TODO: fast atomic
|
|
}
|
|
return p;
|
|
}
|
|
|
|
// Put g on local runnable queue.
|
|
// TODO(dvyukov): consider using lock-free queue.
|
|
static void
|
|
runqput(P *p, G *gp)
|
|
{
|
|
int32 h, t, s;
|
|
|
|
runtime_lock(p);
|
|
retry:
|
|
h = p->runqhead;
|
|
t = p->runqtail;
|
|
s = p->runqsize;
|
|
if(t == h-1 || (h == 0 && t == s-1)) {
|
|
runqgrow(p);
|
|
goto retry;
|
|
}
|
|
p->runq[t++] = gp;
|
|
if(t == s)
|
|
t = 0;
|
|
p->runqtail = t;
|
|
runtime_unlock(p);
|
|
}
|
|
|
|
// Get g from local runnable queue.
|
|
static G*
|
|
runqget(P *p)
|
|
{
|
|
G *gp;
|
|
int32 t, h, s;
|
|
|
|
if(p->runqhead == p->runqtail)
|
|
return nil;
|
|
runtime_lock(p);
|
|
h = p->runqhead;
|
|
t = p->runqtail;
|
|
s = p->runqsize;
|
|
if(t == h) {
|
|
runtime_unlock(p);
|
|
return nil;
|
|
}
|
|
gp = p->runq[h++];
|
|
if(h == s)
|
|
h = 0;
|
|
p->runqhead = h;
|
|
runtime_unlock(p);
|
|
return gp;
|
|
}
|
|
|
|
// Grow local runnable queue.
|
|
// TODO(dvyukov): consider using fixed-size array
|
|
// and transfer excess to the global list (local queue can grow way too big).
|
|
static void
|
|
runqgrow(P *p)
|
|
{
|
|
G **q;
|
|
int32 s, t, h, t2;
|
|
|
|
h = p->runqhead;
|
|
t = p->runqtail;
|
|
s = p->runqsize;
|
|
t2 = 0;
|
|
q = runtime_malloc(2*s*sizeof(*q));
|
|
while(t != h) {
|
|
q[t2++] = p->runq[h++];
|
|
if(h == s)
|
|
h = 0;
|
|
}
|
|
runtime_free(p->runq);
|
|
p->runq = q;
|
|
p->runqhead = 0;
|
|
p->runqtail = t2;
|
|
p->runqsize = 2*s;
|
|
}
|
|
|
|
// Steal half of elements from local runnable queue of p2
|
|
// and put onto local runnable queue of p.
|
|
// Returns one of the stolen elements (or nil if failed).
|
|
static G*
|
|
runqsteal(P *p, P *p2)
|
|
{
|
|
G *gp, *gp1;
|
|
int32 t, h, s, t2, h2, s2, c, i;
|
|
|
|
if(p2->runqhead == p2->runqtail)
|
|
return nil;
|
|
// sort locks to prevent deadlocks
|
|
if(p < p2)
|
|
runtime_lock(p);
|
|
runtime_lock(p2);
|
|
if(p2->runqhead == p2->runqtail) {
|
|
runtime_unlock(p2);
|
|
if(p < p2)
|
|
runtime_unlock(p);
|
|
return nil;
|
|
}
|
|
if(p >= p2)
|
|
runtime_lock(p);
|
|
// now we've locked both queues and know the victim is not empty
|
|
h = p->runqhead;
|
|
t = p->runqtail;
|
|
s = p->runqsize;
|
|
h2 = p2->runqhead;
|
|
t2 = p2->runqtail;
|
|
s2 = p2->runqsize;
|
|
gp = p2->runq[h2++]; // return value
|
|
if(h2 == s2)
|
|
h2 = 0;
|
|
// steal roughly half
|
|
if(t2 > h2)
|
|
c = (t2 - h2) / 2;
|
|
else
|
|
c = (s2 - h2 + t2) / 2;
|
|
// copy
|
|
for(i = 0; i != c; i++) {
|
|
// the target queue is full?
|
|
if(t == h-1 || (h == 0 && t == s-1))
|
|
break;
|
|
// the victim queue is empty?
|
|
if(t2 == h2)
|
|
break;
|
|
gp1 = p2->runq[h2++];
|
|
if(h2 == s2)
|
|
h2 = 0;
|
|
p->runq[t++] = gp1;
|
|
if(t == s)
|
|
t = 0;
|
|
}
|
|
p->runqtail = t;
|
|
p2->runqhead = h2;
|
|
runtime_unlock(p2);
|
|
runtime_unlock(p);
|
|
return gp;
|
|
}
|
|
|
|
void runtime_testSchedLocalQueue(void)
|
|
__asm__("runtime.testSchedLocalQueue");
|
|
|
|
void
|
|
runtime_testSchedLocalQueue(void)
|
|
{
|
|
P p;
|
|
G gs[1000];
|
|
int32 i, j;
|
|
|
|
runtime_memclr((byte*)&p, sizeof(p));
|
|
p.runqsize = 1;
|
|
p.runqhead = 0;
|
|
p.runqtail = 0;
|
|
p.runq = runtime_malloc(p.runqsize*sizeof(*p.runq));
|
|
|
|
for(i = 0; i < (int32)nelem(gs); i++) {
|
|
if(runqget(&p) != nil)
|
|
runtime_throw("runq is not empty initially");
|
|
for(j = 0; j < i; j++)
|
|
runqput(&p, &gs[i]);
|
|
for(j = 0; j < i; j++) {
|
|
if(runqget(&p) != &gs[i]) {
|
|
runtime_printf("bad element at iter %d/%d\n", i, j);
|
|
runtime_throw("bad element");
|
|
}
|
|
}
|
|
if(runqget(&p) != nil)
|
|
runtime_throw("runq is not empty afterwards");
|
|
}
|
|
}
|
|
|
|
void runtime_testSchedLocalQueueSteal(void)
|
|
__asm__("runtime.testSchedLocalQueueSteal");
|
|
|
|
void
|
|
runtime_testSchedLocalQueueSteal(void)
|
|
{
|
|
P p1, p2;
|
|
G gs[1000], *gp;
|
|
int32 i, j, s;
|
|
|
|
runtime_memclr((byte*)&p1, sizeof(p1));
|
|
p1.runqsize = 1;
|
|
p1.runqhead = 0;
|
|
p1.runqtail = 0;
|
|
p1.runq = runtime_malloc(p1.runqsize*sizeof(*p1.runq));
|
|
|
|
runtime_memclr((byte*)&p2, sizeof(p2));
|
|
p2.runqsize = nelem(gs);
|
|
p2.runqhead = 0;
|
|
p2.runqtail = 0;
|
|
p2.runq = runtime_malloc(p2.runqsize*sizeof(*p2.runq));
|
|
|
|
for(i = 0; i < (int32)nelem(gs); i++) {
|
|
for(j = 0; j < i; j++) {
|
|
gs[j].sig = 0;
|
|
runqput(&p1, &gs[j]);
|
|
}
|
|
gp = runqsteal(&p2, &p1);
|
|
s = 0;
|
|
if(gp) {
|
|
s++;
|
|
gp->sig++;
|
|
}
|
|
while((gp = runqget(&p2)) != nil) {
|
|
s++;
|
|
gp->sig++;
|
|
}
|
|
while((gp = runqget(&p1)) != nil)
|
|
gp->sig++;
|
|
for(j = 0; j < i; j++) {
|
|
if(gs[j].sig != 1) {
|
|
runtime_printf("bad element %d(%d) at iter %d\n", j, gs[j].sig, i);
|
|
runtime_throw("bad element");
|
|
}
|
|
}
|
|
if(s != i/2 && s != i/2+1) {
|
|
runtime_printf("bad steal %d, want %d or %d, iter %d\n",
|
|
s, i/2, i/2+1, i);
|
|
runtime_throw("bad steal");
|
|
}
|
|
}
|
|
}
|
|
|
|
void
|
|
runtime_proc_scan(void (*addroot)(Obj))
|
|
{
|
|
addroot((Obj){(byte*)&runtime_sched, sizeof runtime_sched, 0});
|
|
}
|