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Message-ID: <20230621023534.GA236337@ziqianlu-dell>
Date: Wed, 21 Jun 2023 10:35:34 +0800
From: Aaron Lu <aaron.lu@...el.com>
To: David Vernet <void@...ifault.com>
CC: Peter Zijlstra <peterz@...radead.org>,
<linux-kernel@...r.kernel.org>, <mingo@...hat.com>,
<juri.lelli@...hat.com>, <vincent.guittot@...aro.org>,
<rostedt@...dmis.org>, <dietmar.eggemann@....com>,
<bsegall@...gle.com>, <mgorman@...e.de>, <bristot@...hat.com>,
<vschneid@...hat.com>, <joshdon@...gle.com>,
<roman.gushchin@...ux.dev>, <tj@...nel.org>, <kernel-team@...a.com>
Subject: Re: [RFC PATCH 3/3] sched: Implement shared wakequeue in CFS
On Tue, Jun 20, 2023 at 12:36:26PM -0500, David Vernet wrote:
> On Fri, Jun 16, 2023 at 08:53:38AM +0800, Aaron Lu wrote:
> > I also tried that on the 18cores/36threads/LLC Skylake and the contention
> > is indeed much smaller than UDP_RR:
> >
> > 7.30% 7.29% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
> >
> > But I wouldn't say it's entirely gone. Also consider Skylake has a lot
> > fewer cores per LLC than later Intel servers like Icelake and Sapphire
> > Rapids and I expect things would be worse on those two machines.
>
> I cannot reproduce this contention locally, even on a slightly larger
With netperf client number equal to nr_cpu?
> Skylake. Not really sure what to make of the difference here. Perhaps
> it's because you're running with CONFIG_SCHED_CORE=y? What is the
Yes I had that config on but I didn't tag any tasks or groups.
> change in throughput when you run the default workload on your SKL?
The throughput dropped a little with SWQUEUE:
avg_throughput native_queued_spin_lock_slowpath%
NO_SWQUEUE: 9528.061111111108 0.09%
SWQUEUE: 8984.369722222222 8.05%
avg_throughput: average throughput of all netperf client's throughput,
higher is better.
I run this workload like this:
"
netserver
for i in `seq 72`; do
netperf -l 60 -n 72 -6 &
done
sleep 30
perf record -ag -e cycles:pp -- sleep 5 &
wait
"
(the '-n 72' should be redundant but I just keep it there)
Thanks,
Aaron
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