linux-kernel - Re: [LKP] Re: [sched] bdfcae1140: will-it-scale.per_thread

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Message-ID: <1597497813.35294.1603372755111.JavaMail.zimbra@efficios.com>
Date:   Thu, 22 Oct 2020 09:19:15 -0400 (EDT)
From:   Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:     Xing Zhengjun <zhengjun.xing@...ux.intel.com>,
        Anton Blanchard <anton@...ibm.com>, anton@...abs.org
Cc:     Rong Chen <rong.a.chen@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Boqun Feng <boqun.feng@...il.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Will Deacon <will@...nel.org>, paulmck <paulmck@...nel.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Andy Lutomirski <luto@...capital.net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        0day robot <lkp@...el.com>, lkp <lkp@...ts.01.org>,
        zhengjun xing <zhengjun.xing@...el.com>,
        aubrey li <aubrey.li@...ux.intel.com>,
        yu c chen <yu.c.chen@...el.com>
Subject: Re: [LKP] Re: [sched] bdfcae1140: will-it-scale.per_thread_ops
 -37.0% regression

----- On Oct 21, 2020, at 9:54 PM, Xing Zhengjun zhengjun.xing@...ux.intel.com wrote:
[...]
> In fact, 0-day just copy the will-it-scale benchmark from the GitHub, if
> you think the will-it-scale benchmark has some issues, you can
> contribute your idea and help to improve it, later we will update the
> will-it-scale benchmark to the new version.

This is why I CC'd the maintainer of the will-it-scale github project, Anton Blanchard.
My main intent is to report this issue to him, but I have not heard back from him yet.
Is this project maintained ? Let me try to add his ozlabs.org address in CC.

> For this test case, if we bind the workload to a specific CPU, then it
> will hide the scheduler balance issue. In the real world, we seldom bind
> the CPU...

When you say that you bind the workload to a specific CPU, is that done
outside of the will-it-scale testsuite, thus limiting the entire testsuite
to a single CPU, or you expect that internally the will-it-scale context-switch1
test gets affined to a single specific CPU/core/hardware thread through use of
hwloc ?

Thanks,

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com