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authorMike Galbraith <efault@gmx.de>2010-03-11 17:17:13 +0100
committerIngo Molnar <mingo@elte.hu>2010-03-11 18:32:49 +0100
commit39c0cbe2150cbd848a25ba6cdb271d1ad46818ad (patch)
tree7b9c356b39a2b50219398ce534d7d64e7ab4bf06 /kernel/time
parent41acab8851a0408c1d5ad6c21a07456f88b54d40 (diff)
downloadop-kernel-dev-39c0cbe2150cbd848a25ba6cdb271d1ad46818ad.zip
op-kernel-dev-39c0cbe2150cbd848a25ba6cdb271d1ad46818ad.tar.gz
sched: Rate-limit nohz
Entering nohz code on every micro-idle is costing ~10% throughput for netperf TCP_RR when scheduling cross-cpu. Rate limiting entry fixes this, but raises ticks a bit. On my Q6600, an idle box goes from ~85 interrupts/sec to 128. The higher the context switch rate, the more nohz entry costs. With this patch and some cycle recovery patches in my tree, max cross cpu context switch rate is improved by ~16%, a large portion of which of which is this ratelimiting. Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1268301003.6785.28.camel@marge.simson.net> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/tick-sched.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index f992762..f25735a 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -262,6 +262,9 @@ void tick_nohz_stop_sched_tick(int inidle)
goto end;
}
+ if (nohz_ratelimit(cpu))
+ goto end;
+
ts->idle_calls++;
/* Read jiffies and the time when jiffies were updated last */
do {
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