Commit 43148951 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin Committed by Ingo Molnar
Browse files

sched: Micro-optimize by dropping unnecessary task_rq() calls 



We always know the rq used, let's just pass it around.
This seems to cut the size of scheduler core down a tiny bit:

Before:

  [linux]$ size kernel/sched/core.o.orig
     text    data     bss     dec     hex filename
    62760   16130    3876   82766   1434e kernel/sched/core.o.orig

After:

  [linux]$ size kernel/sched/core.o.patched
     text    data     bss     dec     hex filename
    62566   16130    3876   82572   1428c kernel/sched/core.o.patched

Probably speeds it up as well.

Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20130922142054.GA11499@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent f48627e6

kernel/sched/core.c

+3 −3
Original line number Diff line number Diff line
@@ -767,14 +767,14 @@ static void set_load_weight(struct task_struct *p) 
static void enqueue_task(struct rq *rq, struct task_struct *p, int flags)

{

	update_rq_clock(rq);

	sched_info_queued(p);

	sched_info_queued(rq, p);

	p->sched_class->enqueue_task(rq, p, flags);

}



static void dequeue_task(struct rq *rq, struct task_struct *p, int flags)

{

	update_rq_clock(rq);

	sched_info_dequeued(p);

	sched_info_dequeued(rq, p);

	p->sched_class->dequeue_task(rq, p, flags);

}
@@ -1839,7 +1839,7 @@ prepare_task_switch(struct rq *rq, struct task_struct *prev, 
		    struct task_struct *next)

{

	trace_sched_switch(prev, next);

	sched_info_switch(prev, next);

	sched_info_switch(rq, prev, next);

	perf_event_task_sched_out(prev, next);

	fire_sched_out_preempt_notifiers(prev, next);

	prepare_lock_switch(rq, next);

kernel/sched/stats.h

+24 −22
Original line number Diff line number Diff line
@@ -59,9 +59,9 @@ static inline void sched_info_reset_dequeued(struct task_struct *t) 
 * from dequeue_task() to account for possible rq->clock skew across cpus. The

 * delta taken on each cpu would annul the skew.

 */

static inline void sched_info_dequeued(struct task_struct *t)

static inline void sched_info_dequeued(struct rq *rq, struct task_struct *t)

{

	unsigned long long now = rq_clock(task_rq(t)), delta = 0;

	unsigned long long now = rq_clock(rq), delta = 0;



	if (unlikely(sched_info_on()))

		if (t->sched_info.last_queued)
@@ -69,7 +69,7 @@ static inline void sched_info_dequeued(struct task_struct *t) 
	sched_info_reset_dequeued(t);

	t->sched_info.run_delay += delta;



	rq_sched_info_dequeued(task_rq(t), delta);

	rq_sched_info_dequeued(rq, delta);

}



/*
@@ -77,9 +77,9 @@ static inline void sched_info_dequeued(struct task_struct *t) 
 * long it was waiting to run.  We also note when it began so that we

 * can keep stats on how long its timeslice is.

 */

static void sched_info_arrive(struct task_struct *t)

static void sched_info_arrive(struct rq *rq, struct task_struct *t)

{

	unsigned long long now = rq_clock(task_rq(t)), delta = 0;

	unsigned long long now = rq_clock(rq), delta = 0;



	if (t->sched_info.last_queued)

		delta = now - t->sched_info.last_queued;
@@ -88,7 +88,7 @@ static void sched_info_arrive(struct task_struct *t) 
	t->sched_info.last_arrival = now;

	t->sched_info.pcount++;



	rq_sched_info_arrive(task_rq(t), delta);

	rq_sched_info_arrive(rq, delta);

}



/*
@@ -96,11 +96,11 @@ static void sched_info_arrive(struct task_struct *t) 
 * the timestamp if it is already not set.  It's assumed that

 * sched_info_dequeued() will clear that stamp when appropriate.

 */

static inline void sched_info_queued(struct task_struct *t)

static inline void sched_info_queued(struct rq *rq, struct task_struct *t)

{

	if (unlikely(sched_info_on()))

		if (!t->sched_info.last_queued)

			t->sched_info.last_queued = rq_clock(task_rq(t));

			t->sched_info.last_queued = rq_clock(rq);

}



/*
@@ -111,15 +111,15 @@ static inline void sched_info_queued(struct task_struct *t) 
 * sched_info_queued() to mark that it has now again started waiting on

 * the runqueue.

 */

static inline void sched_info_depart(struct task_struct *t)

static inline void sched_info_depart(struct rq *rq, struct task_struct *t)

{

	unsigned long long delta = rq_clock(task_rq(t)) -

	unsigned long long delta = rq_clock(rq) -

					t->sched_info.last_arrival;



	rq_sched_info_depart(task_rq(t), delta);

	rq_sched_info_depart(rq, delta);



	if (t->state == TASK_RUNNING)

		sched_info_queued(t);

		sched_info_queued(rq, t);

}



/*
@@ -128,32 +128,34 @@ static inline void sched_info_depart(struct task_struct *t) 
 * the idle task.)  We are only called when prev != next.

 */

static inline void

__sched_info_switch(struct task_struct *prev, struct task_struct *next)

__sched_info_switch(struct rq *rq,

		    struct task_struct *prev, struct task_struct *next)

{

	struct rq *rq = task_rq(prev);



	/*

	 * prev now departs the cpu.  It's not interesting to record

	 * stats about how efficient we were at scheduling the idle

	 * process, however.

	 */

	if (prev != rq->idle)

		sched_info_depart(prev);

		sched_info_depart(rq, prev);



	if (next != rq->idle)

		sched_info_arrive(next);

		sched_info_arrive(rq, next);

}

static inline void

sched_info_switch(struct task_struct *prev, struct task_struct *next)

sched_info_switch(struct rq *rq,

		  struct task_struct *prev, struct task_struct *next)

{

	if (unlikely(sched_info_on()))

		__sched_info_switch(prev, next);

		__sched_info_switch(rq, prev, next);

}

#else

#define sched_info_queued(t)			do { } while (0)

#define sched_info_queued(rq, t)		do { } while (0)

#define sched_info_reset_dequeued(t)	do { } while (0)

#define sched_info_dequeued(t)			do { } while (0)

#define sched_info_switch(t, next)		do { } while (0)

#define sched_info_dequeued(rq, t)		do { } while (0)

#define sched_info_depart(rq, t)		do { } while (0)

#define sched_info_arrive(rq, next)		do { } while (0)

#define sched_info_switch(rq, t, next)		do { } while (0)

#endif /* CONFIG_SCHEDSTATS || CONFIG_TASK_DELAY_ACCT */



/*

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