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Commit 4a0deca6 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf_counter: generic context switch event 



Impact: cleanup

Use the generic software events for context switches.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Orig-LKML-Reference: <20090319194233.283522645@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 01ef09d9

include/linux/sched.h

+0 −1
Original line number Diff line number Diff line
@@ -138,7 +138,6 @@ extern unsigned long nr_running(void); 
extern unsigned long nr_uninterruptible(void);

extern unsigned long nr_active(void);

extern unsigned long nr_iowait(void);

extern u64 cpu_nr_switches(int cpu);

extern u64 cpu_nr_migrations(int cpu);



extern unsigned long get_parent_ip(unsigned long addr);

kernel/perf_counter.c

+4 −56
Original line number Diff line number Diff line
@@ -710,10 +710,13 @@ void perf_counter_task_sched_out(struct task_struct *task, int cpu) 
{

	struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);

	struct perf_counter_context *ctx = &task->perf_counter_ctx;

	struct pt_regs *regs;



	if (likely(!cpuctx->task_ctx))

		return;



	regs = task_pt_regs(task);

	perf_swcounter_event(PERF_COUNT_CONTEXT_SWITCHES, 1, 1, regs);

	__perf_counter_sched_out(ctx, cpuctx);



	cpuctx->task_ctx = NULL;
@@ -1667,58 +1670,6 @@ static const struct hw_perf_counter_ops perf_ops_task_clock = { 
	.read		= task_clock_perf_counter_read,

};



/*

 * Software counter: context switches

 */



static u64 get_context_switches(struct perf_counter *counter)

{

	struct task_struct *curr = counter->ctx->task;



	if (curr)

		return curr->nvcsw + curr->nivcsw;

	return cpu_nr_switches(smp_processor_id());

}



static void context_switches_perf_counter_update(struct perf_counter *counter)

{

	u64 prev, now;

	s64 delta;



	prev = atomic64_read(&counter->hw.prev_count);

	now = get_context_switches(counter);



	atomic64_set(&counter->hw.prev_count, now);



	delta = now - prev;



	atomic64_add(delta, &counter->count);

}



static void context_switches_perf_counter_read(struct perf_counter *counter)

{

	context_switches_perf_counter_update(counter);

}



static int context_switches_perf_counter_enable(struct perf_counter *counter)

{

	if (counter->prev_state <= PERF_COUNTER_STATE_OFF)

		atomic64_set(&counter->hw.prev_count,

			     get_context_switches(counter));

	return 0;

}



static void context_switches_perf_counter_disable(struct perf_counter *counter)

{

	context_switches_perf_counter_update(counter);

}



static const struct hw_perf_counter_ops perf_ops_context_switches = {

	.enable		= context_switches_perf_counter_enable,

	.disable	= context_switches_perf_counter_disable,

	.read		= context_switches_perf_counter_read,

};



/*

 * Software counter: cpu migrations

 */
@@ -1808,11 +1759,8 @@ sw_perf_counter_init(struct perf_counter *counter) 
	case PERF_COUNT_PAGE_FAULTS:

	case PERF_COUNT_PAGE_FAULTS_MIN:

	case PERF_COUNT_PAGE_FAULTS_MAJ:

		hw_ops = &perf_ops_generic;

		break;

	case PERF_COUNT_CONTEXT_SWITCHES:

		if (!counter->hw_event.exclude_kernel)

			hw_ops = &perf_ops_context_switches;

		hw_ops = &perf_ops_generic;

		break;

	case PERF_COUNT_CPU_MIGRATIONS:

		if (!counter->hw_event.exclude_kernel)

kernel/sched.c

+0 −6
Original line number Diff line number Diff line
@@ -2900,14 +2900,8 @@ unsigned long nr_active(void) 


/*

 * Externally visible per-cpu scheduler statistics:

 * cpu_nr_switches(cpu) - number of context switches on that cpu

 * cpu_nr_migrations(cpu) - number of migrations into that cpu

 */

u64 cpu_nr_switches(int cpu)

{

	return cpu_rq(cpu)->nr_switches;

}



u64 cpu_nr_migrations(int cpu)

{

	return cpu_rq(cpu)->nr_migrations_in;