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Commit bae43c99 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

perf counters: implement PERF_COUNT_TASK_CLOCK 



Impact: add new perf-counter type

The 'task clock' counter counts the amount of time a task is executing,
in nanoseconds. It stops ticking when a task is scheduled out either due
to it blocking, sleeping or it being preempted.

This counter type is a Linux kernel based abstraction, it is available
even if the hardware does not support native hardware performance counters.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 01b2838c

include/linux/perf_counter.h

+5 −2
Original line number Diff line number Diff line
@@ -50,8 +50,11 @@ enum hw_event_types { 
	 */

	PERF_COUNT_CPU_CLOCK		= -1,

	PERF_COUNT_TASK_CLOCK		= -2,

	PERF_COUNT_PAGE_FAULTS		= -3,

	PERF_COUNT_CONTEXT_SWITCHES	= -4,

	/*

	 * Future software events:

	 */

	/* PERF_COUNT_PAGE_FAULTS	= -3,

	   PERF_COUNT_CONTEXT_SWITCHES	= -4, */

};



/*

kernel/perf_counter.c

+22 −0
Original line number Diff line number Diff line
@@ -855,6 +855,25 @@ static const struct hw_perf_counter_ops perf_ops_cpu_clock = { 
	.hw_perf_counter_read		= cpu_clock_perf_counter_read,

};



static void task_clock_perf_counter_enable(struct perf_counter *counter)

{

}



static void task_clock_perf_counter_disable(struct perf_counter *counter)

{

}



static void task_clock_perf_counter_read(struct perf_counter *counter)

{

	atomic64_counter_set(counter, current->se.sum_exec_runtime);

}



static const struct hw_perf_counter_ops perf_ops_task_clock = {

	.hw_perf_counter_enable		= task_clock_perf_counter_enable,

	.hw_perf_counter_disable	= task_clock_perf_counter_disable,

	.hw_perf_counter_read		= task_clock_perf_counter_read,

};



static const struct hw_perf_counter_ops *

sw_perf_counter_init(struct perf_counter *counter)

{
@@ -864,6 +883,9 @@ sw_perf_counter_init(struct perf_counter *counter) 
	case PERF_COUNT_CPU_CLOCK:

		hw_ops = &perf_ops_cpu_clock;

		break;

	case PERF_COUNT_TASK_CLOCK:

		hw_ops = &perf_ops_task_clock;

		break;

	default:

		break;

	}