linux-kernel - Re: [RFC PATCH v3 00/16] Core scheduling v3

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Date:   Thu, 30 May 2019 22:04:39 +0800
From:   Aubrey Li <aubrey.intel@...il.com>
To:     Vineeth Remanan Pillai <vpillai@...italocean.com>
Cc:     Nishanth Aravamudan <naravamudan@...italocean.com>,
        Julien Desfossez <jdesfossez@...italocean.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Paul Turner <pjt@...gle.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Linux List Kernel Mailing <linux-kernel@...r.kernel.org>,
        Subhra Mazumdar <subhra.mazumdar@...cle.com>,
        Frédéric Weisbecker <fweisbec@...il.com>,
        Kees Cook <keescook@...omium.org>,
        Greg Kerr <kerrnel@...gle.com>, Phil Auld <pauld@...hat.com>,
        Aaron Lu <aaron.lwe@...il.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [RFC PATCH v3 00/16] Core scheduling v3

On Thu, May 30, 2019 at 4:36 AM Vineeth Remanan Pillai
<vpillai@...italocean.com> wrote:
>
> Third iteration of the Core-Scheduling feature.
>
> This version fixes mostly correctness related issues in v2 and
> addresses performance issues. Also, addressed some crashes related
> to cgroups and cpu hotplugging.
>
> We have tested and verified that incompatible processes are not
> selected during schedule. In terms of performance, the impact
> depends on the workload:
> - on CPU intensive applications that use all the logical CPUs with
>   SMT enabled, enabling core scheduling performs better than nosmt.
> - on mixed workloads with considerable io compared to cpu usage,
>   nosmt seems to perform better than core scheduling.

My testing scripts can not be completed on this version. I figured out the
number of cpu utilization report entry didn't reach my minimal requirement.
Then I wrote a simple script to verify.
====================
$ cat test.sh
#!/bin/sh

for i in `seq 1 10`
do
    echo `date`, $i
    sleep 1
done
====================

Normally it works as below:

Thu May 30 14:13:40 CST 2019, 1
Thu May 30 14:13:41 CST 2019, 2
Thu May 30 14:13:42 CST 2019, 3
Thu May 30 14:13:43 CST 2019, 4
Thu May 30 14:13:44 CST 2019, 5
Thu May 30 14:13:45 CST 2019, 6
Thu May 30 14:13:46 CST 2019, 7
Thu May 30 14:13:47 CST 2019, 8
Thu May 30 14:13:48 CST 2019, 9
Thu May 30 14:13:49 CST 2019, 10

When the system was running 32 sysbench threads and
32 gemmbench threads, it worked as below(the system
has ~38% idle time)
Thu May 30 14:14:20 CST 2019, 1
Thu May 30 14:14:21 CST 2019, 2
Thu May 30 14:14:22 CST 2019, 3
Thu May 30 14:14:24 CST 2019, 4 <=======x=
Thu May 30 14:14:25 CST 2019, 5
Thu May 30 14:14:26 CST 2019, 6
Thu May 30 14:14:28 CST 2019, 7 <=======x=
Thu May 30 14:14:29 CST 2019, 8
Thu May 30 14:14:31 CST 2019, 9 <=======x=
Thu May 30 14:14:34 CST 2019, 10 <=======x=

And it got worse when the system was running 64/64 case,
the system still had ~3% idle time
Thu May 30 14:26:40 CST 2019, 1
Thu May 30 14:26:46 CST 2019, 2
Thu May 30 14:26:53 CST 2019, 3
Thu May 30 14:27:01 CST 2019, 4
Thu May 30 14:27:03 CST 2019, 5
Thu May 30 14:27:11 CST 2019, 6
Thu May 30 14:27:31 CST 2019, 7
Thu May 30 14:27:32 CST 2019, 8
Thu May 30 14:27:41 CST 2019, 9
Thu May 30 14:27:56 CST 2019, 10

Any thoughts?

Thanks,
-Aubrey