From: Peter Zijlstra <peterz@infradead.org>
To: Uladzislau Rezki <urezki@gmail.com>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
Mike Galbraith <efault@gmx.de>,
Dmitry Adamushko <dmitry.adamushko@gmail.com>,
Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] sched: check pinned tasks before nohz balance, linux-4.2-rc5
Date: Wed, 5 Aug 2015 17:29:53 +0200 [thread overview]
Message-ID: <20150805152953.GB25159@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <CA+KHdyVB8oTDih2xrQLz1ZGZgdaM6NR1hfeuyCvYw=GjiKzYgg@mail.gmail.com>
On Wed, Aug 05, 2015 at 05:14:34PM +0200, Uladzislau Rezki wrote:
> While investigating “load balancer” logic, I run into interesting
> behavior related
> to affinity and NO_HZ idle balance. Basically saying if there are two
> tasks running
> in certain rq and one of them is pinned/affined, then scheduler will
> trigger load
> balance on power collapsed core via soft irq.
>
> The corner case here is it may fail to unbalance because of affinity, as a
> result core that has two tasks will interrupt any found idle one each its timer
> tick, what can lead to wasting of power, especially in mobile area, what is
> our case.
>
> Do you have any concern with provided patch?
Yeah, I should go fix the set_cpus_allowed rework :/
lkml.kernel.org/r/20150515154333.712161952@infradead.org
prev parent reply other threads:[~2015-08-05 15:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-05 15:14 Uladzislau Rezki
2015-08-05 15:29 ` Peter Zijlstra [this message]
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