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Message-ID: <4e271e7d95fe862c9f201b6f04b16b1423ae3dcb.camel@gmx.de>
Subject: Re: [PATCH v8 2/2] sched/fair: Introduce SIS_CURRENT to wake up
 short task on current CPU
From:   Mike Galbraith <efault@gmx.de>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Chen Yu <yu.c.chen@intel.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Ingo Molnar <mingo@redhat.com>,
        Juri Lelli <juri.lelli@redhat.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        Tim Chen <tim.c.chen@intel.com>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ben Segall <bsegall@google.com>,
        K Prateek Nayak <kprateek.nayak@amd.com>,
        Abel Wu <wuyun.abel@bytedance.com>,
        Yicong Yang <yangyicong@hisilicon.com>,
        "Gautham R . Shenoy" <gautham.shenoy@amd.com>,
        Honglei Wang <wanghonglei@didichuxing.com>,
        Len Brown <len.brown@intel.com>,
        Chen Yu <yu.chen.surf@gmail.com>,
        Tianchen Ding <dtcccc@linux.alibaba.com>,
        Joel Fernandes <joel@joelfernandes.org>,
        Josh Don <joshdon@google.com>,
        kernel test robot <yujie.liu@intel.com>,
        Arjan Van De Ven <arjan.van.de.ven@intel.com>,
        Aaron Lu <aaron.lu@intel.com>, linux-kernel@vger.kernel.org
Date:   Tue, 02 May 2023 04:51:51 +0200
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Precedence: bulk

On Mon, 2023-05-01 at 20:49 +0200, Peter Zijlstra wrote:
> On Mon, May 01, 2023 at 05:32:05PM +0200, Mike Galbraith wrote:
> > On Mon, 2023-05-01 at 15:48 +0200, Peter Zijlstra wrote:
> > >
> > > Throughput=C2=A0 646.55 MB/sec=C2=A0=C2=A0 2 clients=C2=A0=C2=A0 2 p=
rocs=C2=A0 max_latency=3D0.104 ms
> > > Throughput 1361.06 MB/sec=C2=A0=C2=A0 5 clients=C2=A0=C2=A0 5 procs=
=C2=A0 max_latency=3D0.100 ms
> > > Throughput 1889.82 MB/sec=C2=A0 10 clients=C2=A0 10 procs=C2=A0 max_=
latency=3D0.154 ms
> > > Throughput 2406.57 MB/sec=C2=A0 20 clients=C2=A0 20 procs=C2=A0 max_=
latency=3D3.667 ms
> > > Throughput 2318.00 MB/sec=C2=A0 40 clients=C2=A0 40 procs=C2=A0 max_=
latency=3D0.390 ms
> > > Throughput 2384.85 MB/sec=C2=A0 80 clients=C2=A0 80 procs=C2=A0 max_=
latency=3D1.371 ms
> > >
> > >
> > > So what's going on here? I don't see anything exciting happening at =
the
> > > 40 mark. At the same time, I can't seem to reproduce Mike's latency =
pile
> > > up either :/
> >
> > Are you running tbench in the GUI so the per second output stimulates
> > assorted goo?=C2=A0 I'm using KDE fwtw.
>
> Nah, the IVB-EP is headless, doesn't even have systemd on, still running
> sysvinit.

Turns out load distribution on Yu's box wasn't going wonky way early
after all, so WA_WEIGHT's evil side is off topic wrt $subject.  Hohum.

	-Mike