From: Peter Zijlstra <peterz@infradead.org>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Jirka Hladky <jhladky@redhat.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Kamil Kolakowski <kkolakow@redhat.com>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Yuyang Du <yuyang.du@intel.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Mike Galbraith <umgwanakikbuti@gmail.com>,
Benjamin Segall <bsegall@google.com>,
Paul Turner <pjt@google.com>,
Matt Fleming <matt@codeblueprint.co.uk>
Subject: Re: Kernel 4.7rc3 - Performance drop 30-40% for SPECjbb2005 and SPECjvm2008 benchmarks against 4.6 kernel
Date: Fri, 24 Jun 2016 15:45:15 +0200 [thread overview]
Message-ID: <20160624134515.GC30154@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <CAKfTPtC1DemKu86ykG3G498vq+HpOnj+35LD+s=wovs1OpK-zw@mail.gmail.com>
On Fri, Jun 24, 2016 at 03:23:37PM +0200, Vincent Guittot wrote:
> > It seemed like a simple and cheap way to increase accuracy, nothing more
> > behind it until the commit you referred to.
>
> Thanks for the clarification.
> I thought that the difference should always be smaller than 1/64th of
> the cfs_rq->avg.load_avg thanks to update_tg_load_avg
Right, another reason I just remembered is that it ensures:
tg_weight >= cfs_rq_weight
Because if this is the only task in the entire group and cfs_rq
increased (but did not exceed the 1/64th threshold) you get the group
weight being smaller than the entity weight, which would be weird.
next prev parent reply other threads:[~2016-06-24 13:45 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-16 16:38 Kernel 4.7rc3 - Performance drop 30-40% for SPECjbb2005 and SPECjvm2008 benchmarks against 4.6 kernel Jirka Hladky
2016-06-16 17:22 ` Peter Zijlstra
2016-06-16 23:04 ` Jirka Hladky
2016-06-21 13:17 ` Jirka Hladky
2016-06-22 7:16 ` Peter Zijlstra
2016-06-22 7:49 ` Peter Zijlstra
2016-06-22 7:54 ` Peter Zijlstra
2016-06-22 9:52 ` Jirka Hladky
2016-06-22 11:12 ` Peter Zijlstra
2016-06-22 12:37 ` Jirka Hladky
2016-06-22 12:46 ` Jirka Hladky
2016-06-22 14:41 ` Jirka Hladky
2016-06-22 20:59 ` Peter Zijlstra
2016-06-22 8:20 ` Jirka Hladky
2016-06-23 18:33 ` Peter Zijlstra
2016-06-23 18:43 ` Peter Zijlstra
2016-06-24 7:44 ` Jirka Hladky
2016-06-24 8:08 ` Peter Zijlstra
2016-06-24 8:20 ` Jirka Hladky
2016-06-24 12:02 ` Peter Zijlstra
2016-06-24 12:09 ` Jirka Hladky
2016-06-24 12:30 ` Peter Zijlstra
2016-06-24 12:35 ` Jirka Hladky
2016-06-24 12:44 ` Vincent Guittot
2016-06-24 13:08 ` Jirka Hladky
2016-06-24 13:09 ` Peter Zijlstra
2016-06-24 13:23 ` Vincent Guittot
2016-06-24 13:33 ` Peter Zijlstra
2016-06-24 13:45 ` Peter Zijlstra [this message]
2016-06-24 13:42 ` Peter Zijlstra
2016-06-24 15:54 ` Peter Zijlstra
2016-06-24 22:13 ` Jirka Hladky
-- strict thread matches above, loose matches on Subject: below --
2016-06-22 7:37 Branimir Maksimovic
2016-06-22 8:25 ` Jirka Hladky
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