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Commit 1d1c7ddb authored by Ingo Molnar's avatar Ingo Molnar
Browse files

perf counters: add prctl interface to disable/enable counters 



Add a way for self-monitoring tasks to disable/enable counters summarily,
via a prctl:

	PR_TASK_PERF_COUNTERS_DISABLE		31
	PR_TASK_PERF_COUNTERS_ENABLE		32

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent bae43c99

include/linux/perf_counter.h

+4 −0
Original line number Diff line number Diff line
@@ -213,6 +213,8 @@ extern u64 hw_perf_save_disable(void); 
extern void hw_perf_restore(u64 ctrl);

extern void atomic64_counter_set(struct perf_counter *counter, u64 val64);

extern u64 atomic64_counter_read(struct perf_counter *counter);

extern int perf_counter_task_disable(void);

extern int perf_counter_task_enable(void);



#else

static inline void
@@ -226,6 +228,8 @@ static inline void perf_counter_notify(struct pt_regs *regs) { } 
static inline void perf_counter_print_debug(void)			{ }

static inline void hw_perf_restore(u64 ctrl)			{ }

static inline u64 hw_perf_save_disable(void)		      { return 0; }

static inline int perf_counter_task_disable(void)	{ return -EINVAL; }

static inline int perf_counter_task_enable(void)	{ return -EINVAL; }

#endif



#endif /* _LINUX_PERF_COUNTER_H */

include/linux/prctl.h

+3 −0
Original line number Diff line number Diff line
@@ -85,4 +85,7 @@ 
#define PR_SET_TIMERSLACK 29

#define PR_GET_TIMERSLACK 30



#define PR_TASK_PERF_COUNTERS_DISABLE		31

#define PR_TASK_PERF_COUNTERS_ENABLE		32



#endif /* _LINUX_PRCTL_H */

kernel/perf_counter.c

+79 −7
Original line number Diff line number Diff line
@@ -415,6 +415,9 @@ counter_sched_in(struct perf_counter *counter, 
		 struct perf_counter_context *ctx,

		 int cpu)

{

	if (counter->active == -1)

		return;



	counter->hw_ops->hw_perf_counter_enable(counter);

	counter->active = 1;

	counter->oncpu = cpu;	/* TODO: put 'cpu' into cpuctx->cpu */
@@ -479,6 +482,79 @@ void perf_counter_task_sched_in(struct task_struct *task, int cpu) 
	cpuctx->task_ctx = ctx;

}



int perf_counter_task_disable(void)

{

	struct task_struct *curr = current;

	struct perf_counter_context *ctx = &curr->perf_counter_ctx;

	struct perf_counter *counter;

	u64 perf_flags;

	int cpu;



	if (likely(!ctx->nr_counters))

		return 0;



	local_irq_disable();

	cpu = smp_processor_id();



	perf_counter_task_sched_out(curr, cpu);



	spin_lock(&ctx->lock);



	/*

	 * Disable all the counters:

	 */

	perf_flags = hw_perf_save_disable();



	list_for_each_entry(counter, &ctx->counter_list, list_entry) {

		WARN_ON_ONCE(counter->active == 1);

		counter->active = -1;

	}

	hw_perf_restore(perf_flags);



	spin_unlock(&ctx->lock);



	local_irq_enable();



	return 0;

}



int perf_counter_task_enable(void)

{

	struct task_struct *curr = current;

	struct perf_counter_context *ctx = &curr->perf_counter_ctx;

	struct perf_counter *counter;

	u64 perf_flags;

	int cpu;



	if (likely(!ctx->nr_counters))

		return 0;



	local_irq_disable();

	cpu = smp_processor_id();



	spin_lock(&ctx->lock);



	/*

	 * Disable all the counters:

	 */

	perf_flags = hw_perf_save_disable();



	list_for_each_entry(counter, &ctx->counter_list, list_entry) {

		if (counter->active != -1)

			continue;

		counter->active = 0;

	}

	hw_perf_restore(perf_flags);



	spin_unlock(&ctx->lock);



	perf_counter_task_sched_in(curr, cpu);



	local_irq_enable();



	return 0;

}



void perf_counter_task_tick(struct task_struct *curr, int cpu)

{

	struct perf_counter_context *ctx = &curr->perf_counter_ctx;
@@ -951,13 +1027,9 @@ perf_counter_alloc(struct perf_counter_hw_event *hw_event, 
 * @cpu:		target cpu

 * @group_fd:		group leader counter fd

 */

asmlinkage int sys_perf_counter_open(



	struct perf_counter_hw_event	*hw_event_uptr		__user,

	pid_t				pid,

	int				cpu,

	int				group_fd)



asmlinkage int

sys_perf_counter_open(struct perf_counter_hw_event *hw_event_uptr __user,

		      pid_t pid, int cpu, int group_fd)

{

	struct perf_counter *counter, *group_leader;

	struct perf_counter_hw_event hw_event;

kernel/sys.c

+7 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/prctl.h>

#include <linux/highuid.h>

#include <linux/fs.h>

#include <linux/perf_counter.h>

#include <linux/resource.h>

#include <linux/kernel.h>

#include <linux/kexec.h>
@@ -1716,6 +1717,12 @@ asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3, 
		case PR_SET_TSC:

			error = SET_TSC_CTL(arg2);

			break;

		case PR_TASK_PERF_COUNTERS_DISABLE:

			error = perf_counter_task_disable();

			break;

		case PR_TASK_PERF_COUNTERS_ENABLE:

			error = perf_counter_task_enable();

			break;

		case PR_GET_TIMERSLACK:

			error = current->timer_slack_ns;

			break;