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From:   Vincent Guittot <vincent.guittot@linaro.org>
Date:   Thu, 3 Dec 2020 10:03:41 +0100
Message-ID: <CAKfTPtALPjSvOZ2xf9cka9R-1uqi3AHQ+GYy7asT3wfvmLqaXw@mail.gmail.com>
Subject: Re: [RFC PATCH v2 2/2] scheduler: add scheduler level for clusters
To:     "Song Bao Hua (Barry Song)" <song.bao.hua@hisilicon.com>
Cc:     Valentin Schneider <valentin.schneider@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        "Cc: Len Brown" <lenb@kernel.org>,
        "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
        Jonathan Cameron <jonathan.cameron@huawei.com>,
        Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
        Mark Rutland <mark.rutland@arm.com>,
        LAK <linux-arm-kernel@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
        Linuxarm <linuxarm@huawei.com>, "xuwei (O)" <xuwei5@huawei.com>,
        "Zengtao (B)" <prime.zeng@hisilicon.com>
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On Wed, 2 Dec 2020 at 21:58, Song Bao Hua (Barry Song)
<song.bao.hua@hisilicon.com> wrote:
>
> >
> > Sorry. Please ignore this. I added some printk here while testing
> > one numa. Will update you the data in another email.
>
> Re-tested in one NUMA node(cpu0-cpu23):
>
> g=1
> Running in threaded mode with 1 groups using 40 file descriptors
> Each sender will pass 100000 messages of 100 bytes
> w/o: 7.689 7.485 7.485 7.458 7.524 7.539 7.738 7.693 7.568 7.674=7.5853
> w/ : 7.516 7.941 7.374 7.963 7.881 7.910 7.420 7.556 7.695 7.441=7.6697
> w/ but dropped select_idle_cluster:
>      7.752 7.739 7.739 7.571 7.545 7.685 7.407 7.580 7.605 7.487=7.611
>
> g=2
> Running in threaded mode with 2 groups using 40 file descriptors
> Each sender will pass 100000 messages of 100 bytes
> w/o: 10.127 10.119 10.070 10.196 10.057 10.111 10.045 10.164 10.162
> 9.955=10.1006
> w/ : 9.694 9.654 9.612 9.649 9.686 9.734 9.607 9.842 9.690 9.710=9.6878
> w/ but dropped select_idle_cluster:
>      9.877 10.069 9.951 9.918 9.947 9.790 9.906 9.820 9.863 9.906=9.9047
>
> g=3
> Running in threaded mode with 3 groups using 40 file descriptors
> Each sender will pass 100000 messages of 100 bytes
> w/o: 15.885 15.254 15.932 15.647 16.120 15.878 15.857 15.759 15.674
> 15.721=15.7727
> w/ : 14.974 14.657 13.969 14.985 14.728 15.665 15.191 14.995 14.946
> 14.895=14.9005
> w/ but dropped select_idle_cluster:
>      15.405 15.177 15.373 15.187 15.450 15.540 15.278 15.628 15.228 15.325=15.3591
>
> g=4
> Running in threaded mode with 4 groups using 40 file descriptors
> Each sender will pass 100000 messages of 100 bytes
> w/o: 20.014 21.025 21.119 21.235 19.767 20.971 20.962 20.914 21.090 21.090=20.8187
> w/ : 20.331 20.608 20.338 20.445 20.456 20.146 20.693 20.797 21.381 20.452=20.5647
> w/ but dropped select_idle_cluster:
>      19.814 20.126 20.229 20.350 20.750 20.404 19.957 19.888 20.226 20.562=20.2306
>

I assume that you have run this on v5.9 as previous tests.
The results don't show any real benefit of select_idle_cluster()
inside a node whereas this is where we could expect most of the
benefit. We have to understand why we have such an impact on numa
tests only.

> Thanks
> Barry
>