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Subject[tip:sched/core] sched: Micro-optimize by dropping unnecessary task_rq() calls
Commit-ID:  4314895165623879937f46d767673654662b570c
Gitweb: http://git.kernel.org/tip/4314895165623879937f46d767673654662b570c
Author: Michael S. Tsirkin <mst@redhat.com>
AuthorDate: Sun, 22 Sep 2013 17:20:54 +0300
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 25 Sep 2013 13:51:06 +0200

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: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20130922142054.GA11499@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/sched/core.c | 6 +++---
kernel/sched/stats.h | 46 ++++++++++++++++++++++++----------------------
2 files changed, 27 insertions(+), 25 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index c2283c5..ac57967 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -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);
diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h
index c7edee7..4ab7043 100644
--- a/kernel/sched/stats.h
+++ b/kernel/sched/stats.h
@@ -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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