From: Mike Galbraith <efault@gmx.de>
To: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
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: Tue, 28 Feb 2012 06:05:14 +0100 [thread overview]
Message-ID: <1330405514.17181.29.camel@marge.simpson.net> (raw)
In-Reply-To: <1330380683.23436.16.camel@sbsiddha-desk.sc.intel.com>
On Mon, 2012-02-27 at 14:11 -0800, Suresh Siddha wrote:
> On Sat, 2012-02-25 at 09:30 +0100, Mike Galbraith wrote:
> > My less rotund config shows the L2 penalty decidedly more prominently.
> > We used to have avg_overlap as a synchronous wakeup hint, but it was
> > broken by preemption and whatnot, got the axe to recover some cycles. A
> > reliable and dirt cheap replacement would be a good thing to have.
> >
> > TCP_RR and tbench are far way away from the overlap breakeven point on
> > E5620, whereas with Q6600s shared L2, you can start converting overlap
> > into throughput almost immediately.
> >
> > 2.4 GHz E5620
> > Throughput 248.994 MB/sec 1 procs SD_SHARE_PKG_RESOURCES
> > Throughput 379.488 MB/sec 1 procs !SD_SHARE_PKG_RESOURCES
> >
> > 2.4 GHz Q6600
> > Throughput 299.049 MB/sec 1 procs SD_SHARE_PKG_RESOURCES
> > Throughput 300.018 MB/sec 1 procs !SD_SHARE_PKG_RESOURCES
> >
>
> Also it is not always about just the L2 cache being shared/not or
> warm/cold etc. It also depends on the core c-states/p-states etc. It
> will cost waking up an idle core and the cost will depend on the what
> core-c state it is in. And also if we ping-pong between cores often,
> cpufreq governor will come and request for a lower core p-state even
> though the load was keeping one core or the other in the socket always
> busy at any given point of time.
Yeah, pinning yields a couple percent on Q6600 box, more on E5620
despite its spiffier gearbox.. likely turbo-boost doing it's thing.
-Mike
next prev parent reply other threads:[~2012-02-28 5:05 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
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 [this message]
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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