diff options
| author | Paul Turner <pjt@google.com> | 2011-11-07 20:26:33 -0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2011-11-16 08:48:18 +0100 |
| commit | 56f570e512eeb5b412cb3a62234adc446a8eb32b (patch) | |
| tree | cabaea188d6e35c077abc34fda40cc83aea9ea37 /kernel/sched_fair.c | |
| parent | fccfdc6f0d8c83c854eeb6d93aa158f0e551bd49 (diff) | |
| download | linux-56f570e512eeb5b412cb3a62234adc446a8eb32b.tar.gz linux-56f570e512eeb5b412cb3a62234adc446a8eb32b.tar.bz2 linux-56f570e512eeb5b412cb3a62234adc446a8eb32b.zip | |
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.c | 15 |
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; |