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From: Michael Ellerman <mpe@ellerman.id.au>
To: Tejun Heo <htejun@gmail.com>, Peter Zijlstra <peterz@infradead.org>
Cc: Gautham R Shenoy <ego@linux.vnet.ibm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Abdul Haleem <abdhalee@linux.vnet.ibm.com>,
	Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>,
	linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] workqueue:Fix affinity of an unbound worker of a node with 1 online CPU
Date: Thu, 16 Jun 2016 22:11:24 +1000	[thread overview]
Message-ID: <1466079084.19127.2.camel@ellerman.id.au> (raw)
In-Reply-To: <20160615160112.GC24102@mtj.duckdns.org>

On Wed, 2016-06-15 at 12:01 -0400, Tejun Heo wrote:
> On Wed, Jun 15, 2016 at 03:14:15PM +0200, Peter Zijlstra wrote:
> > On Wed, Jun 15, 2016 at 06:20:33PM +0530, Gautham R Shenoy wrote:
> > > We will no longer have the optimization in
> > > restore_unbound_workers_cpumask() but I suppose we don't lose much by
> > > resetting the affinity every time a CPU in the pool->attr->cpumask
> > > comes online.
> > 
> > Right; optimizing hotplug really isn't worth it. The code needs to be
> > simple and robust (ha! funny).
> 
> The only case it might matter is CPU hotplug being used aggressively
> for power saving.  No idea how popular that is now tho.
> set_cpus_allowed isn't that expensive and phones don't tend to have
> massive number of kworkers, so hopefully it won't show up.
> 
> > In any case, Tejun, does this work for you?
> 
> I'm not sure about the reordering part but for setting affinity on
> each onlining, no objection.  If it ever shows up as performance /
> power regression, we can revisit it later.

Peterz do you want to send a SOB'ed patch, or can we take what you posted and
add your SOB?

And Tejun are you happy to merge this for rc4?

cheers

  reply	other threads:[~2016-06-16 12:11 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-05-19 10:57 WARNING at kernel/sched/core.c:1166 while booting 4.6.0 mainline on ppc64le bare metal abdhalee
2016-05-19 12:34 ` Gavin Shan
2016-05-26 15:11 ` Gautham R Shenoy
2016-06-07 12:29   ` Abdul Haleem
2016-06-07 15:14     ` [PATCH 0/2] Fix CPU Online handling for unbounded worker threads Gautham R. Shenoy
2016-06-07 15:14       ` [PATCH 1/2] workqueue: Move wq_update_unbound_numa() to the beginning of CPU_ONLINE Gautham R. Shenoy
2016-06-15 15:53         ` Tejun Heo
2016-06-15 19:28           ` Gautham R Shenoy
2016-06-16 19:35             ` Tejun Heo
2016-06-21 14:12               ` Gautham R Shenoy
2016-06-21 15:36                 ` Tejun Heo
2016-06-21 19:37                   ` Peter Zijlstra
2016-06-21 19:43                     ` Tejun Heo
2016-06-21 19:47                       ` Peter Zijlstra
2016-06-22  5:15                         ` Gautham R Shenoy
2016-06-24  9:00               ` [tip:sched/urgent] sched/core: Allow kthreads to fall back to online && !active cpus tip-bot for Tejun Heo
2016-06-07 15:14       ` [PATCH 2/2] workqueue:Fix affinity of an unbound worker of a node with 1 online CPU Gautham R. Shenoy
2016-06-08  6:03         ` Abdul Haleem
2016-06-14 11:22         ` Peter Zijlstra
2016-06-15 10:19           ` Gautham R Shenoy
2016-06-15 11:32             ` Peter Zijlstra
2016-06-15 12:50               ` Gautham R Shenoy
2016-06-15 13:14                 ` Peter Zijlstra
2016-06-15 16:01                   ` Tejun Heo
2016-06-16 12:11                     ` Michael Ellerman [this message]
2016-06-16 12:45                       ` Peter Zijlstra
2016-06-16 19:39                         ` Tejun Heo
2016-06-17  1:49                           ` Michael Ellerman
2016-07-15  5:27                           ` Gautham R Shenoy
2016-07-15  5:30                           ` Michael Ellerman
     [not found]                           ` <57887507.911f240a.687de.08c5SMTPIN_ADDED_BROKEN@mx.google.com>
2016-07-15 12:10                             ` Tejun Heo
2016-06-13  5:44       ` [PATCH 0/2] Fix CPU Online handling for unbounded worker threads Gautham R Shenoy

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