Commit 5af42f92 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Peter Zijlstra
Browse files

perf: Shrink the size of the recursion counter. 



There are four recursion counter, one for each context. The type of the
counter is `int' but the counter is used as `bool' since it is only
incremented if zero.
The main goal here is to shrink the whole struct into 32bit int which
can later be added task_struct into an existing hole.

Reduce the type of the recursion counter to an unsigned char, keep the
increment/ decrement operation.

Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: default avatarMarco Elver <elver@google.com>
Link: https://lore.kernel.org/r/20240704170424.1466941-5-bigeasy@linutronix.de
parent c5d93d23

kernel/events/callchain.c

+1 −1
Original line number Diff line number Diff line
@@ -29,7 +29,7 @@ static inline size_t perf_callchain_entry__sizeof(void) 
				 sysctl_perf_event_max_contexts_per_stack));

}



static DEFINE_PER_CPU(int, callchain_recursion[PERF_NR_CONTEXTS]);

static DEFINE_PER_CPU(u8, callchain_recursion[PERF_NR_CONTEXTS]);

static atomic_t nr_callchain_events;

static DEFINE_MUTEX(callchain_mutex);

static struct callchain_cpus_entries *callchain_cpus_entries;

kernel/events/core.c

+1 −1
Original line number Diff line number Diff line
@@ -9765,7 +9765,7 @@ struct swevent_htable { 
	int				hlist_refcount;



	/* Recursion avoidance in each contexts */

	int				recursion[PERF_NR_CONTEXTS];

	u8				recursion[PERF_NR_CONTEXTS];

};



static DEFINE_PER_CPU(struct swevent_htable, swevent_htable);

kernel/events/internal.h

+2 −2
Original line number Diff line number Diff line
@@ -208,7 +208,7 @@ arch_perf_out_copy_user(void *dst, const void *src, unsigned long n) 


DEFINE_OUTPUT_COPY(__output_copy_user, arch_perf_out_copy_user)



static inline int get_recursion_context(int *recursion)

static inline int get_recursion_context(u8 *recursion)

{

	unsigned char rctx = interrupt_context_level();
@@ -221,7 +221,7 @@ static inline int get_recursion_context(int *recursion) 
	return rctx;

}



static inline void put_recursion_context(int *recursion, int rctx)

static inline void put_recursion_context(u8 *recursion, int rctx)

{

	barrier();

	recursion[rctx]--;