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ftrace: trace irq disabled critical timings
This patch adds latency tracing for critical timings
(how long interrupts are disabled for).
"irqsoff" is added to /debugfs/tracing/available_tracers
Note:
tracing_max_latency
also holds the max latency for irqsoff (in usecs).
(default to large number so one must start latency tracing)
tracing_thresh
threshold (in usecs) to always print out if irqs off
is detected to be longer than stated here.
If irq_thresh is non-zero, then max_irq_latency
is ignored.
Here's an example of a trace with ftrace_enabled = 0
=======
preemption latency trace v1.1.5 on 2.6.24-rc7
Signed-off-by: Ingo Molnar <mingo@elte.hu>
--------------------------------------------------------------------
latency: 100 us, #3/3, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2)
-----------------
| task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0)
-----------------
=> started at: _spin_lock_irqsave+0x2a/0xb7
=> ended at: _spin_unlock_irqrestore+0x32/0x5f
_------=> CPU#
/ _-----=> irqs-off
| / _----=> need-resched
|| / _---=> hardirq/softirq
||| / _--=> preempt-depth
|||| /
||||| delay
cmd pid ||||| time | caller
\ / ||||| \ | /
swapper-0 1d.s3 0us+: _spin_lock_irqsave+0x2a/0xb7 (e1000_update_stats+0x47/0x64c [e1000])
swapper-0 1d.s3 100us : _spin_unlock_irqrestore+0x32/0x5f (e1000_update_stats+0x641/0x64c [e1000])
swapper-0 1d.s3 100us : trace_hardirqs_on_caller+0x75/0x89 (_spin_unlock_irqrestore+0x32/0x5f)
vim:ft=help
=======
And this is a trace with ftrace_enabled == 1
=======
preemption latency trace v1.1.5 on 2.6.24-rc7
--------------------------------------------------------------------
latency: 102 us, #12/12, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2)
-----------------
| task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0)
-----------------
=> started at: _spin_lock_irqsave+0x2a/0xb7
=> ended at: _spin_unlock_irqrestore+0x32/0x5f
_------=> CPU#
/ _-----=> irqs-off
| / _----=> need-resched
|| / _---=> hardirq/softirq
||| / _--=> preempt-depth
|||| /
||||| delay
cmd pid ||||| time | caller
\ / ||||| \ | /
swapper-0 1dNs3 0us+: _spin_lock_irqsave+0x2a/0xb7 (e1000_update_stats+0x47/0x64c [e1000])
swapper-0 1dNs3 46us : e1000_read_phy_reg+0x16/0x225 [e1000] (e1000_update_stats+0x5e2/0x64c [e1000])
swapper-0 1dNs3 46us : e1000_swfw_sync_acquire+0x10/0x99 [e1000] (e1000_read_phy_reg+0x49/0x225 [e1000])
swapper-0 1dNs3 46us : e1000_get_hw_eeprom_semaphore+0x12/0xa6 [e1000] (e1000_swfw_sync_acquire+0x36/0x99 [e1000])
swapper-0 1dNs3 47us : __const_udelay+0x9/0x47 (e1000_read_phy_reg+0x116/0x225 [e1000])
swapper-0 1dNs3 47us+: __delay+0x9/0x50 (__const_udelay+0x45/0x47)
swapper-0 1dNs3 97us : preempt_schedule+0xc/0x84 (__delay+0x4e/0x50)
swapper-0 1dNs3 98us : e1000_swfw_sync_release+0xc/0x55 [e1000] (e1000_read_phy_reg+0x211/0x225 [e1000])
swapper-0 1dNs3 99us+: e1000_put_hw_eeprom_semaphore+0x9/0x35 [e1000] (e1000_swfw_sync_release+0x50/0x55 [e1000])
swapper-0 1dNs3 101us : _spin_unlock_irqrestore+0xe/0x5f (e1000_update_stats+0x641/0x64c [e1000])
swapper-0 1dNs3 102us : _spin_unlock_irqrestore+0x32/0x5f (e1000_update_stats+0x641/0x64c [e1000])
swapper-0 1dNs3 102us : trace_hardirqs_on_caller+0x75/0x89 (_spin_unlock_irqrestore+0x32/0x5f)
vim:ft=help
=======
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Steven Rostedt
committed by
Thomas Gleixner
Thomas Gleixner
parent
352ad25aa4
commit
81d68a96a3
@@ -5,6 +5,7 @@
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obj-$(CONFIG_SMP) := msr-on-cpu.o
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lib-y := delay_$(BITS).o
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lib-y += thunk_$(BITS).o
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lib-y += usercopy_$(BITS).o getuser_$(BITS).o putuser_$(BITS).o
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lib-y += memcpy_$(BITS).o
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47
arch/x86/lib/thunk_32.S
Normal file
47
arch/x86/lib/thunk_32.S
Normal file
@@ -0,0 +1,47 @@
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/*
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* Trampoline to trace irqs off. (otherwise CALLER_ADDR1 might crash)
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* Copyright 2008 by Steven Rostedt, Red Hat, Inc
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* (inspired by Andi Kleen's thunk_64.S)
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* Subject to the GNU public license, v.2. No warranty of any kind.
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*/
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#include <linux/linkage.h>
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#define ARCH_TRACE_IRQS_ON \
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pushl %eax; \
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pushl %ecx; \
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pushl %edx; \
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call trace_hardirqs_on; \
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popl %edx; \
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popl %ecx; \
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popl %eax;
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#define ARCH_TRACE_IRQS_OFF \
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pushl %eax; \
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pushl %ecx; \
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pushl %edx; \
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call trace_hardirqs_off; \
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popl %edx; \
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popl %ecx; \
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popl %eax;
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#ifdef CONFIG_TRACE_IRQFLAGS
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/* put return address in eax (arg1) */
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.macro thunk_ra name,func
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.globl \name
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\name:
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pushl %eax
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pushl %ecx
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pushl %edx
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/* Place EIP in the arg1 */
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movl 3*4(%esp), %eax
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call \func
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popl %edx
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popl %ecx
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popl %eax
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ret
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.endm
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thunk_ra trace_hardirqs_on_thunk,trace_hardirqs_on_caller
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thunk_ra trace_hardirqs_off_thunk,trace_hardirqs_off_caller
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#endif
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@@ -2,6 +2,7 @@
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* Save registers before calling assembly functions. This avoids
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* disturbance of register allocation in some inline assembly constructs.
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* Copyright 2001,2002 by Andi Kleen, SuSE Labs.
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* Added trace_hardirqs callers - Copyright 2007 Steven Rostedt, Red Hat, Inc.
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* Subject to the GNU public license, v.2. No warranty of any kind.
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*/
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@@ -42,8 +43,22 @@
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#endif
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#ifdef CONFIG_TRACE_IRQFLAGS
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thunk trace_hardirqs_on_thunk,trace_hardirqs_on
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thunk trace_hardirqs_off_thunk,trace_hardirqs_off
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/* put return address in rdi (arg1) */
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.macro thunk_ra name,func
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.globl \name
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\name:
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CFI_STARTPROC
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SAVE_ARGS
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/* SAVE_ARGS pushs 9 elements */
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/* the next element would be the rip */
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movq 9*8(%rsp), %rdi
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call \func
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jmp restore
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CFI_ENDPROC
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.endm
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thunk_ra trace_hardirqs_on_thunk,trace_hardirqs_on_caller
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thunk_ra trace_hardirqs_off_thunk,trace_hardirqs_off_caller
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#endif
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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