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authorPaul Turner <pjt@google.com>2011-11-07 20:26:33 -0800
committerIngo Molnar <mingo@elte.hu>2011-11-16 08:48:18 +0100
commit56f570e512eeb5b412cb3a62234adc446a8eb32b (patch)
treecabaea188d6e35c077abc34fda40cc83aea9ea37 /kernel/sched_fair.c
parentfccfdc6f0d8c83c854eeb6d93aa158f0e551bd49 (diff)
downloadlinux-linaro-stable-56f570e512eeb5b412cb3a62234adc446a8eb32b.tar.gz
sched: Use jump labels to reduce overhead when bandwidth control is inactive
Now that the linkage of jump-labels has been fixed they show a measurable improvement in overhead for the enabled-but-unused case. Workload is: 'taskset -c 0 perf stat --repeat 50 -e instructions,cycles,branches bash -c "for ((i=0;i<5;i++)); do $(dirname $0)/pipe-test 20000; done"' There's a speedup for all situations: instructions cycles branches ------------------------------------------------------------------------- Intel Westmere base 806611770 745895590 146765378 +jumplabel 803090165 (-0.44%) 713381840 (-4.36%) 144561130 AMD Barcelona base 824657415 740055589 148855354 +jumplabel 821056910 (-0.44%) 737558389 (-0.34%) 146635229 Signed-off-by: Paul Turner <pjt@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20111108042736.560831357@google.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched_fair.c')
-rw-r--r--kernel/sched_fair.c15
1 files changed, 12 insertions, 3 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index a78ed2736ba7..a608593df243 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1421,7 +1421,7 @@ static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
static __always_inline void account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
unsigned long delta_exec)
{
- if (!cfs_rq->runtime_enabled)
+ if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled)
return;
__account_cfs_rq_runtime(cfs_rq, delta_exec);
@@ -1429,13 +1429,13 @@ static __always_inline void account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
{
- return cfs_rq->throttled;
+ return cfs_bandwidth_used() && cfs_rq->throttled;
}
/* check whether cfs_rq, or any parent, is throttled */
static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
{
- return cfs_rq->throttle_count;
+ return cfs_bandwidth_used() && cfs_rq->throttle_count;
}
/*
@@ -1756,6 +1756,9 @@ static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
{
+ if (!cfs_bandwidth_used())
+ return;
+
if (!cfs_rq->runtime_enabled || cfs_rq->nr_running)
return;
@@ -1801,6 +1804,9 @@ static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
*/
static void check_enqueue_throttle(struct cfs_rq *cfs_rq)
{
+ if (!cfs_bandwidth_used())
+ return;
+
/* an active group must be handled by the update_curr()->put() path */
if (!cfs_rq->runtime_enabled || cfs_rq->curr)
return;
@@ -1818,6 +1824,9 @@ static void check_enqueue_throttle(struct cfs_rq *cfs_rq)
/* conditionally throttle active cfs_rq's from put_prev_entity() */
static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq)
{
+ if (!cfs_bandwidth_used())
+ return;
+
if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0))
return;