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perf: Use jump_labels to optimize the scheduler hooks

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Trades a call + conditional + ret for an unconditional jmp.

Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20101014203625.501657727@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2010-10-14 17:57:23 +02:00 committed by Ingo Molnar
parent 8b92538d84
commit 82cd6def98
2 changed files with 34 additions and 17 deletions
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27
include/linux/perf_event.h
View File

@ -487,6 +487,7 @@ struct perf_guest_info_callbacks {
#include <linux/ftrace.h>
#include <linux/cpu.h>
#include <linux/irq_work.h>
#include <linux/jump_label_ref.h>
#include <asm/atomic.h>
#include <asm/local.h>
@ -895,8 +896,30 @@ extern void perf_pmu_unregister(struct pmu *pmu);
extern int perf_num_counters(void);
extern const char *perf_pmu_name(void);
extern void perf_event_task_sched_in(struct task_struct *task);
extern void perf_event_task_sched_out(struct task_struct *task, struct task_struct *next);
extern void __perf_event_task_sched_in(struct task_struct *task);
extern void __perf_event_task_sched_out(struct task_struct *task, struct task_struct *next);
extern atomic_t perf_task_events;
static inline void perf_event_task_sched_in(struct task_struct *task)
{
JUMP_LABEL(&perf_task_events, have_events);
return;
have_events:
__perf_event_task_sched_in(task);
}
static inline
void perf_event_task_sched_out(struct task_struct *task, struct task_struct *next)
{
JUMP_LABEL(&perf_task_events, have_events);
return;
have_events:
__perf_event_task_sched_out(task, next);
}
extern int perf_event_init_task(struct task_struct *child);
extern void perf_event_exit_task(struct task_struct *child);
extern void perf_event_free_task(struct task_struct *task);

24
kernel/perf_event.c
View File

@ -34,7 +34,7 @@
#include <asm/irq_regs.h>
static atomic_t nr_events __read_mostly;
atomic_t perf_task_events __read_mostly;
static atomic_t nr_mmap_events __read_mostly;
static atomic_t nr_comm_events __read_mostly;
static atomic_t nr_task_events __read_mostly;
@ -1311,8 +1311,8 @@ void perf_event_context_sched_out(struct task_struct *task, int ctxn,
* accessing the event control register. If a NMI hits, then it will
* not restart the event.
*/
void perf_event_task_sched_out(struct task_struct *task,
struct task_struct *next)
void __perf_event_task_sched_out(struct task_struct *task,
struct task_struct *next)
{
int ctxn;
@ -1337,14 +1337,6 @@ static void task_ctx_sched_out(struct perf_event_context *ctx,
cpuctx->task_ctx = NULL;
}
/*
* Called with IRQs disabled
*/
static void __perf_event_task_sched_out(struct perf_event_context *ctx)
{
task_ctx_sched_out(ctx, EVENT_ALL);
}
/*
* Called with IRQs disabled
*/
@ -1494,7 +1486,7 @@ void perf_event_context_sched_in(struct perf_event_context *ctx)
* accessing the event control register. If a NMI hits, then it will
* keep the event running.
*/
void perf_event_task_sched_in(struct task_struct *task)
void __perf_event_task_sched_in(struct task_struct *task)
{
struct perf_event_context *ctx;
int ctxn;
@ -2216,7 +2208,8 @@ static void free_event(struct perf_event *event)
irq_work_sync(&event->pending);
if (!event->parent) {
atomic_dec(&nr_events);
if (event->attach_state & PERF_ATTACH_TASK)
jump_label_dec(&perf_task_events);
if (event->attr.mmap || event->attr.mmap_data)
atomic_dec(&nr_mmap_events);
if (event->attr.comm)
@ -5354,7 +5347,8 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
event->pmu = pmu;
if (!event->parent) {
atomic_inc(&nr_events);
if (event->attach_state & PERF_ATTACH_TASK)
jump_label_inc(&perf_task_events);
if (event->attr.mmap || event->attr.mmap_data)
atomic_inc(&nr_mmap_events);
if (event->attr.comm)
@ -5849,7 +5843,7 @@ static void perf_event_exit_task_context(struct task_struct *child, int ctxn)
* our context.
*/
child_ctx = child->perf_event_ctxp[ctxn];
__perf_event_task_sched_out(child_ctx);
task_ctx_sched_out(child_ctx, EVENT_ALL);
/*
* Take the context lock here so that if find_get_context is