From: Mike Galbraith <efault@gmx.de>
To: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@elte.hu>, Paul Turner <pjt@google.com>
Subject: Re: sched: Avoid SMT siblings in select_idle_sibling() if possible
Date: Wed, 16 Nov 2011 10:24:15 +0100 [thread overview]
Message-ID: <1321435455.5072.64.camel@marge.simson.net> (raw)
In-Reply-To: <1321406062.16760.60.camel@sbsiddha-desk.sc.intel.com>
On Tue, 2011-11-15 at 17:14 -0800, Suresh Siddha wrote:
> How about this patch which is more self explanatory?
Actually, after further testing/reading, it looks to me like both of
these patches have a problem. They'll never select SMT siblings (so a
skip SIBLING should accomplish the same).
This patch didn't select an idle core either though, where Peter's did.
Tested by pinning a hog to cores 1-3, then starting up an unpinned
tbench pair. Peter's patch didn't do the BadThing (as in bad for
TCP_RR/tbench) in that case, but should have.
> + sg = sd->groups;
> + do {
> + if (!cpumask_intersects(sched_group_cpus(sg),
> + tsk_cpus_allowed(p)))
> + goto next;
>
> + for_each_cpu(i, sched_group_cpus(sg)) {
> + if (!idle_cpu(i))
> + goto next;
Say target is CPU0. Groups are 0,4 1,5 2,6 3,7. 0-3 are first CPUs
encountered in MC groups, all were busy. At SIBLING level, the only
group is 0,4. First encountered CPU of sole group is busy target, so
we're done.. so we return busy target.
> + target = cpumask_first_and(sched_group_cpus(sg),
> + tsk_cpus_allowed(p));
At SIBLING, group = 0,4 = 0x5, 0x5 & 0xff = 1 = target.
-Mike
next prev parent reply other threads:[~2011-11-16 9:24 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-15 9:46 sched: Avoid SMT siblings in select_idle_sibling() if possible Peter Zijlstra
2011-11-16 1:14 ` Suresh Siddha
2011-11-16 9:24 ` Mike Galbraith [this message]
2011-11-16 18:37 ` Suresh Siddha
2011-11-17 1:59 ` Mike Galbraith
2011-11-17 15:38 ` Mike Galbraith
2011-11-17 15:56 ` Peter Zijlstra
2011-11-17 16:38 ` Mike Galbraith
2011-11-17 17:36 ` Suresh Siddha
2011-11-18 15:14 ` Mike Galbraith
2011-11-18 15:17 ` [patch 1/6] sched: use rt.nr_cpus_allowed to recover select_task_rq() cycles Mike Galbraith
2011-11-18 15:35 ` Peter Zijlstra
2011-11-18 17:34 ` Mike Galbraith
2011-11-22 14:17 ` Mike Galbraith
2011-11-22 14:18 ` [patch 1/7] " Mike Galbraith
2011-12-06 9:50 ` [tip:sched/core] sched: Use " tip-bot for Mike Galbraith
2011-11-22 14:20 ` [patch 2/7] sched: save some hrtick_start_fair cycles Mike Galbraith
2011-12-06 20:20 ` [tip:sched/core] sched: Save " tip-bot for Mike Galbraith
2011-11-22 14:21 ` [patch 3/7] sched: set skip_clock_update in yield_task_fair() Mike Galbraith
2011-11-23 11:53 ` Peter Zijlstra
2011-11-23 12:06 ` Mike Galbraith
2011-11-23 14:48 ` Peter Zijlstra
2011-11-24 3:50 ` Mike Galbraith
2011-11-24 10:12 ` Peter Zijlstra
2011-11-25 6:39 ` Mike Galbraith
2011-12-06 9:51 ` [tip:sched/core] sched: Set " tip-bot for Mike Galbraith
2011-11-22 14:22 ` [patch 4/7] sched: convert rq->avg_idle to rq->avg_event Mike Galbraith
2011-11-23 11:55 ` Peter Zijlstra
2011-11-23 12:09 ` Mike Galbraith
2011-11-23 12:27 ` Peter Zijlstra
2011-11-23 12:57 ` Mike Galbraith
2011-11-23 14:21 ` Mike Galbraith
2011-11-22 14:23 ` [patch 5/7] sched: ratelimit select_idle_sibling()for sync wakeups Mike Galbraith
2011-11-22 14:24 ` [patch 6/7] sched: use rq->avg_event to resurrect nohz ratelimiting Mike Galbraith
2011-11-23 11:57 ` Peter Zijlstra
2011-11-23 12:35 ` Mike Galbraith
2011-11-22 14:26 ` [patch 7/7] sched: only use TTWU_QUEUE when waker/wakee CPUs do not share top level cache Mike Galbraith
2011-11-23 12:08 ` Peter Zijlstra
2011-11-18 15:39 ` [patch 1/6] sched: use rt.nr_cpus_allowed to recover select_task_rq() cycles Hillf Danton
2011-11-18 15:18 ` [patch 2/6] sched: convert rq->avg_idle to rq->avg_event Mike Galbraith
2011-11-18 15:19 ` [patch 3/6] sched: use rq->avg_event to resurrect nohz ratelimiting Mike Galbraith
2011-11-18 15:36 ` Peter Zijlstra
2011-11-18 17:42 ` Mike Galbraith
2011-11-19 0:51 ` Van De Ven, Arjan
2011-11-19 4:15 ` Mike Galbraith
2011-11-18 15:20 ` [patch 4/6] sched: ratelimit select_idle_sibling()for sync wakeups Mike Galbraith
2011-11-18 15:22 ` [patch 5/6] sched: save some hrtick_start_fair cycles Mike Galbraith
2011-11-18 15:23 ` [patch 6/6] sched: set skip_clock_update in yield_task_fair() Mike Galbraith
2012-02-20 14:41 ` sched: Avoid SMT siblings in select_idle_sibling() if possible Peter Zijlstra
2012-02-20 15:03 ` Srivatsa Vaddagiri
2012-02-20 18:25 ` Mike Galbraith
2012-02-21 0:06 ` Srivatsa Vaddagiri
2012-02-21 6:37 ` Mike Galbraith
2012-02-21 8:09 ` Srivatsa Vaddagiri
2012-02-20 18:14 ` Mike Galbraith
2012-02-20 18:15 ` Peter Zijlstra
2012-02-20 19:07 ` Peter Zijlstra
2012-02-21 5:43 ` Mike Galbraith
2012-02-21 8:32 ` Srivatsa Vaddagiri
2012-02-21 9:21 ` Mike Galbraith
2012-02-21 10:37 ` Peter Zijlstra
2012-02-21 14:58 ` Srivatsa Vaddagiri
2012-02-23 10:49 ` Srivatsa Vaddagiri
2012-02-23 11:19 ` Ingo Molnar
2012-02-23 12:18 ` Srivatsa Vaddagiri
2012-02-23 11:20 ` Srivatsa Vaddagiri
2012-02-23 11:26 ` Ingo Molnar
2012-02-23 11:32 ` Srivatsa Vaddagiri
2012-02-23 16:17 ` Ingo Molnar
2012-02-23 11:21 ` Mike Galbraith
2012-02-25 6:54 ` Srivatsa Vaddagiri
2012-02-25 8:30 ` Mike Galbraith
2012-02-27 22:11 ` Suresh Siddha
2012-02-28 5:05 ` Mike Galbraith
2011-11-17 19:08 ` Suresh Siddha
2011-11-18 15:12 ` Peter Zijlstra
2011-11-18 15:26 ` Mike Galbraith
2011-12-06 9:49 ` [tip:sched/core] sched: Clean up domain traversal in select_idle_sibling() tip-bot for Suresh Siddha
2011-11-18 23:40 ` [tip:sched/core] sched: Avoid SMT siblings in select_idle_sibling() if possible tip-bot for Peter Zijlstra
[not found] <1329764866.2293.376.camhel@twins>
2012-03-05 15:24 ` Srivatsa Vaddagiri
2012-03-06 9:14 ` Ingo Molnar
2012-03-06 10:03 ` Srivatsa Vaddagiri
2012-03-22 15:32 ` Srivatsa Vaddagiri
2012-03-23 6:38 ` Mike Galbraith
2012-03-26 8:29 ` Peter Zijlstra
2012-03-26 8:36 ` Peter Zijlstra
2012-03-26 17:35 ` Srivatsa Vaddagiri
2012-03-26 18:06 ` Peter Zijlstra
2012-03-27 13:56 ` Mike Galbraith
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