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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: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar 2008-12-11 14:59:31 +01:00
parent bae43c9945
commit 1d1c7ddbfa
4 changed files with 93 additions and 7 deletions
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4
include/linux/perf_counter.h
View File

@ -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 */

3
include/linux/prctl.h
View File

@ -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 */

86
kernel/perf_counter.c
View File

@ -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;

7
kernel/sys.c
View File

@ -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;