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Groups > linux.kernel > #1389929
| From | Peter Zijlstra <peterz@infradead.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [patch] sched: Fix smp nice induced group scheduling load distribution woes |
| Date | 2016-04-28 11:20 +0200 |
| Message-ID | <rsQh4-Jd-17@gated-at.bofh.it> (permalink) |
| References | <rratA-7AU-13@gated-at.bofh.it> <rrhbI-4rx-9@gated-at.bofh.it> <rrml4-A9-15@gated-at.bofh.it> <rrKQp-3ck-7@gated-at.bofh.it> <rsrVo-5zE-23@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Wed, Apr 27, 2016 at 09:09:51AM +0200, Mike Galbraith wrote:
> On even a modest sized NUMA box any load that wants to scale
> is essentially reduced to SCHED_IDLE class by smp nice scaling.
> Limit niceness to prevent cramming a box wide load into a too
> small space. Given niceness affects latency, give the user the
> option to completely disable box wide group fairness as well.
Have you tried the (obvious) ?
I suppose we really should just do this (and yuyang's cleanup patches I
suppose). Nobody has ever been able to reproduce those increased power
usage claims and Google is running with this enabled.
---
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 69da6fcaa0e8..968f573413de 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -53,7 +53,7 @@ static inline void cpu_load_update_active(struct rq *this_rq) { }
* when BITS_PER_LONG <= 32 are pretty high and the returns do not justify the
* increased costs.
*/
-#if 0 /* BITS_PER_LONG > 32 -- currently broken: it increases power usage under light load */
+#ifdef CONFIG_64BIT
# define SCHED_LOAD_RESOLUTION 10
# define scale_load(w) ((w) << SCHED_LOAD_RESOLUTION)
# define scale_load_down(w) ((w) >> SCHED_LOAD_RESOLUTION)
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[RFC] The Linux Scheduler: a Decade of Wasted Cores Report Jeff Merkey <linux.mdb@gmail.com> - 2016-04-23 20:30 +0200
Re: [RFC] The Linux Scheduler: a Decade of Wasted Cores Report Brendan Gregg <brendan.d.gregg@gmail.com> - 2016-04-24 03:40 +0200
Re: [RFC] The Linux Scheduler: a Decade of Wasted Cores Report Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-04-24 09:10 +0200
Re: [RFC] The Linux Scheduler: a Decade of Wasted Cores Report Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-04-25 11:20 +0200
[patch] sched: Fix smp nice induced group scheduling load distribution woes Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-04-27 09:20 +0200
Re: [patch] sched: Fix smp nice induced group scheduling load distribution woes Peter Zijlstra <peterz@infradead.org> - 2016-04-28 11:20 +0200
Re: [patch] sched: Fix smp nice induced group scheduling load distribution woes Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-04-28 14:30 +0200
Re: [RFC] The Linux Scheduler: a Decade of Wasted Cores Report Peter Zijlstra <peterz@infradead.org> - 2016-04-25 11:40 +0200
Re: [RFC] The Linux Scheduler: a Decade of Wasted Cores Report Rik van Riel <riel@redhat.com> - 2016-04-25 20:00 +0200
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