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Commit 1ac9bc69 authored by Arun Sharma's avatar Arun Sharma Committed by Ingo Molnar
Browse files

sched/tracing: Add a new tracepoint for sleeptime 



If CONFIG_SCHEDSTATS is defined, the kernel maintains
information about how long the task was sleeping or
in the case of iowait, blocking in the kernel before
getting woken up.

This will be useful for sleep time profiling.

Note: this information is only provided for sched_fair.
Other scheduling classes may choose to provide this in
the future.

Note: the delay includes the time spent on the runqueue
as well.

Signed-off-by: default avatarArun Sharma <asharma@fb.com>
Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Andrew Vagin <avagin@openvz.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1324512940-32060-2-git-send-email-asharma@fb.com


Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 664dfa65

include/trace/events/sched.h

+50 −0
Original line number Diff line number Diff line
@@ -370,6 +370,56 @@ TRACE_EVENT(sched_stat_runtime, 
			(unsigned long long)__entry->vruntime)

);



#ifdef CREATE_TRACE_POINTS

static inline u64 trace_get_sleeptime(struct task_struct *tsk)

{

#ifdef CONFIG_SCHEDSTATS

	u64 block, sleep;



	block = tsk->se.statistics.block_start;

	sleep = tsk->se.statistics.sleep_start;

	tsk->se.statistics.block_start = 0;

	tsk->se.statistics.sleep_start = 0;



	return block ? block : sleep ? sleep : 0;

#else

	return 0;

#endif

}

#endif



/*

 * Tracepoint for accounting sleeptime (time the task is sleeping

 * or waiting for I/O).

 */

TRACE_EVENT(sched_stat_sleeptime,



	TP_PROTO(struct task_struct *tsk, u64 now),



	TP_ARGS(tsk, now),



	TP_STRUCT__entry(

		__array( char,	comm,	TASK_COMM_LEN	)

		__field( pid_t,	pid			)

		__field( u64,	sleeptime		)

	),



	TP_fast_assign(

		memcpy(__entry->comm, tsk->comm, TASK_COMM_LEN);

		__entry->pid		= tsk->pid;

		__entry->sleeptime = trace_get_sleeptime(tsk);

		__entry->sleeptime = __entry->sleeptime ?

				now - __entry->sleeptime : 0;

	)

	TP_perf_assign(

		__perf_count(__entry->sleeptime);

	),



	TP_printk("comm=%s pid=%d sleeptime=%Lu [ns]",

			__entry->comm, __entry->pid,

			(unsigned long long)__entry->sleeptime)

);



/*

 * Tracepoint for showing priority inheritance modifying a tasks

 * priority.

kernel/sched/core.c

+1 −0
Original line number Diff line number Diff line
@@ -1937,6 +1937,7 @@ static void finish_task_switch(struct rq *rq, struct task_struct *prev) 
	local_irq_enable();

#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */

	finish_lock_switch(rq, prev);

	trace_sched_stat_sleeptime(current, rq->clock);



	fire_sched_in_preempt_notifiers(current);

	if (mm)

kernel/sched/fair.c

+0 −2
Original line number Diff line number Diff line
@@ -1003,7 +1003,6 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) 
		if (unlikely(delta > se->statistics.sleep_max))

			se->statistics.sleep_max = delta;



		se->statistics.sleep_start = 0;

		se->statistics.sum_sleep_runtime += delta;



		if (tsk) {
@@ -1020,7 +1019,6 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) 
		if (unlikely(delta > se->statistics.block_max))

			se->statistics.block_max = delta;



		se->statistics.block_start = 0;

		se->statistics.sum_sleep_runtime += delta;



		if (tsk) {