From: Peter Zijlstra <peterz@infradead.org>
To: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <Dietmar.Eggemann@arm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"mingo@kernel.org" <mingo@kernel.org>,
"pjt@google.com" <pjt@google.com>,
"cmetcalf@tilera.com" <cmetcalf@tilera.com>,
"tony.luck@intel.com" <tony.luck@intel.com>,
"alex.shi@linaro.org" <alex.shi@linaro.org>,
"preeti@linux.vnet.ibm.com" <preeti@linux.vnet.ibm.com>,
"linaro-kernel@lists.linaro.org" <linaro-kernel@lists.linaro.org>,
"paulmck@linux.vnet.ibm.com" <paulmck@linux.vnet.ibm.com>,
"corbet@lwn.net" <corbet@lwn.net>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"len.brown@intel.com" <len.brown@intel.com>,
"arjan@linux.intel.com" <arjan@linux.intel.com>,
"amit.kucheria@linaro.org" <amit.kucheria@linaro.org>,
"james.hogan@imgtec.com" <james.hogan@imgtec.com>,
"schwidefsky@de.ibm.com" <schwidefsky@de.ibm.com>,
"heiko.carstens@de.ibm.com" <heiko.carstens@de.ibm.com>
Subject: Re: [RFC] sched: CPU topology try
Date: Wed, 8 Jan 2014 13:42:53 +0100 [thread overview]
Message-ID: <20140108124253.GC31570@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20140108123534.GI2936@e103034-lin>
On Wed, Jan 08, 2014 at 12:35:34PM +0000, Morten Rasmussen wrote:
> > The harder case is where all 3 tasks are of equal weight; in which case
> > fairness would mandate we (slowly) rotate the tasks such that they all
> > get 2/3 time -- we also horribly fail at this :-)
>
> I have encountered that one a number of times. All the middleware noise
> in Android sometimes give that effect.
You've got a typo there: s/middleware/muddleware/ :-)
> I'm not sure if the NUMA guy would like rotating scheduler though :-)
Hurmph ;-) But yes, the N+1 tasks on a N cpu system is rotten; any
static solution gets 2 tasks that run at 50%, any dynamic solution gets
the migration overhead issue.
So while the dynamic solution would indeed allow each task to (on
average) receive N/N+1 time -- a vast improvement over the 50% thing, it
doesn't come without down sides.
next prev parent reply other threads:[~2014-01-08 12:43 UTC|newest]
Thread overview: 101+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-18 11:52 [RFC][PATCH v5 00/14] sched: packing tasks Vincent Guittot
2013-10-18 11:52 ` [RFC][PATCH v5 01/14] sched: add a new arch_sd_local_flags for sched_domain init Vincent Guittot
2013-11-05 14:06 ` Peter Zijlstra
2013-11-05 14:57 ` Vincent Guittot
2013-11-05 22:27 ` Peter Zijlstra
2013-11-06 10:10 ` Vincent Guittot
2013-11-06 13:53 ` Martin Schwidefsky
2013-11-06 14:08 ` Peter Zijlstra
2013-11-12 17:43 ` Dietmar Eggemann
2013-11-12 18:08 ` Peter Zijlstra
2013-11-13 15:47 ` Dietmar Eggemann
2013-11-13 16:29 ` Peter Zijlstra
2013-11-14 10:49 ` Morten Rasmussen
2013-11-14 12:07 ` Peter Zijlstra
2013-12-18 13:13 ` [RFC] sched: CPU topology try Vincent Guittot
2013-12-23 17:22 ` Dietmar Eggemann
2014-01-06 13:41 ` Vincent Guittot
2014-01-06 16:31 ` Peter Zijlstra
2014-01-07 8:32 ` Vincent Guittot
2014-01-07 13:22 ` Peter Zijlstra
2014-01-07 14:10 ` Peter Zijlstra
2014-01-07 15:41 ` Morten Rasmussen
2014-01-07 20:49 ` Peter Zijlstra
2014-01-08 8:32 ` Alex Shi
2014-01-08 8:37 ` Peter Zijlstra
2014-01-08 12:52 ` Morten Rasmussen
2014-01-08 13:04 ` Peter Zijlstra
2014-01-08 13:33 ` Morten Rasmussen
2014-01-08 12:35 ` Morten Rasmussen
2014-01-08 12:42 ` Peter Zijlstra [this message]
2014-01-08 12:45 ` Peter Zijlstra
2014-01-08 13:27 ` Morten Rasmussen
2014-01-08 13:32 ` Peter Zijlstra
2014-01-08 13:45 ` Morten Rasmussen
2014-01-07 14:11 ` Vincent Guittot
2014-01-07 15:37 ` Morten Rasmussen
2014-01-08 8:37 ` Alex Shi
2014-01-06 16:28 ` Peter Zijlstra
2014-01-06 17:15 ` Morten Rasmussen
2014-01-07 9:57 ` Peter Zijlstra
2014-01-01 5:00 ` Preeti U Murthy
2014-01-06 16:33 ` Peter Zijlstra
2014-01-06 16:37 ` Arjan van de Ven
2014-01-06 16:48 ` Peter Zijlstra
2014-01-06 16:54 ` Peter Zijlstra
2014-01-06 17:13 ` Arjan van de Ven
2014-01-07 12:40 ` Vincent Guittot
2014-01-06 16:21 ` Peter Zijlstra
2014-01-07 8:22 ` Vincent Guittot
2014-01-07 9:40 ` Preeti U Murthy
2014-01-07 9:50 ` Peter Zijlstra
2014-01-07 10:39 ` Preeti U Murthy
2014-01-07 11:13 ` Peter Zijlstra
2014-01-07 16:31 ` Preeti U Murthy
2014-01-07 11:20 ` Morten Rasmussen
2014-01-07 12:31 ` Vincent Guittot
2014-01-07 16:51 ` Preeti U Murthy
2013-10-18 11:52 ` [RFC][PATCH v5 03/14] sched: define pack buddy CPUs Vincent Guittot
2013-10-18 11:52 ` [RFC][PATCH v5 04/14] sched: do load balance only with packing cpus Vincent Guittot
2013-10-18 11:52 ` [RFC][PATCH v5 05/14] sched: add a packing level knob Vincent Guittot
2013-11-12 10:32 ` Peter Zijlstra
2013-11-12 10:44 ` Vincent Guittot
2013-11-12 10:55 ` Peter Zijlstra
2013-11-12 10:57 ` Vincent Guittot
2013-10-18 11:52 ` [RFC][PATCH v5 06/14] sched: create a new field with available capacity Vincent Guittot
2013-11-12 10:34 ` Peter Zijlstra
2013-11-12 11:05 ` Vincent Guittot
2013-10-18 11:52 ` [RFC][PATCH v5 07/14] sched: get CPU's activity statistic Vincent Guittot
2013-11-12 10:36 ` Peter Zijlstra
2013-11-12 10:41 ` Peter Zijlstra
2013-10-18 11:52 ` [RFC][PATCH v5 08/14] sched: move load idx selection in find_idlest_group Vincent Guittot
2013-11-12 10:49 ` Peter Zijlstra
2013-11-27 14:10 ` [tip:sched/core] sched/fair: Move " tip-bot for Vincent Guittot
2013-10-18 11:52 ` [RFC][PATCH v5 09/14] sched: update the packing cpu list Vincent Guittot
2013-10-18 11:52 ` [RFC][PATCH v5 10/14] sched: init this_load to max in find_idlest_group Vincent Guittot
2013-10-18 11:52 ` [RFC][PATCH v5 11/14] sched: add a SCHED_PACKING_TASKS config Vincent Guittot
2013-10-18 11:52 ` [RFC][PATCH v5 12/14] sched: create a statistic structure Vincent Guittot
2013-10-18 11:52 ` [RFC][PATCH v5 13/14] sched: differantiate idle cpu Vincent Guittot
2013-10-18 11:52 ` [RFC][PATCH v5 14/14] cpuidle: set the current wake up latency Vincent Guittot
2013-11-11 11:33 ` [RFC][PATCH v5 00/14] sched: packing tasks Catalin Marinas
2013-11-11 16:36 ` Peter Zijlstra
2013-11-11 16:39 ` Arjan van de Ven
2013-11-11 18:18 ` Catalin Marinas
2013-11-11 18:20 ` Arjan van de Ven
2013-11-12 12:06 ` Morten Rasmussen
2013-11-12 16:48 ` Arjan van de Ven
2013-11-12 23:14 ` Catalin Marinas
2013-11-13 16:13 ` Arjan van de Ven
2013-11-13 16:45 ` Catalin Marinas
2013-11-13 17:56 ` Arjan van de Ven
2013-11-12 17:40 ` Catalin Marinas
2013-11-25 18:55 ` Daniel Lezcano
2013-11-11 16:38 ` Peter Zijlstra
2013-11-11 16:40 ` Arjan van de Ven
2013-11-12 10:36 ` Vincent Guittot
2013-11-11 16:54 ` Morten Rasmussen
2013-11-11 18:31 ` Catalin Marinas
2013-11-11 19:26 ` Arjan van de Ven
2013-11-11 22:43 ` Nicolas Pitre
2013-11-11 23:43 ` Catalin Marinas
2013-11-12 12:35 ` Vincent Guittot
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