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From:   Jirka Hladky <jhladky@redhat.com>
Date:   Sun, 9 Sep 2018 16:03:30 +0200
Message-ID: <CAE4VaGBeTy-du_tThkr3w-r2KbYW8m+sRcpDPn9sYeENUy_x4g@mail.gmail.com>
Subject: Re: [SCHEDULER] Performance drop in 4.19 compared to 4.18 kernel
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        "Jakub Ra??ek" <jracek@redhat.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        "kkolakow@redhat.com" <kkolakow@redhat.com>,
        Ingo Molnar <mingo@redhat.com>
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Hi Peter and Srikar,

thanks a lot for the information and for the patches to test!

> I have bounced the 5 patches to you, (one of the 6 has not been applied by
> Peter) so I have skipped that.
> They can also be fetched from
> http://lore.kernel.org/lkml/1533276841-16341-1-git-send-email-srikar@linux.vnet.ibm.com

We have started the benchmarks, I will report the results on Monday.

> I generally run specjbb2005 (single and multi instance).
We also run a single and multi-instance specjbb2005 test.

> I have tried running NAS but I couldn't set it up properly.
We run the OMP variant and we control the number of threads with the
OMP_NUM_THREADS env variable. The setup is quite simple:

cd NPB_sources/config/
mv suite_x86_64.def suite.def
cd ..
make suite

FYI - starting from 4.17 kernel there is a significant performance
drop compared to 4.16 kernel. Mel has come up with a
sched-numa-fast-crossnode-v1r12 patch series
git.kernel.org/pub/scm/linux/kernel/git/mel/linux.git which we have
tested extensively and with it, the benchmarks results are back at
4.16 level. As I understand it, Mel's patch series depends on your
patch series and can be only merged when your patches are completed.

Thanks!
Jirka


On Fri, Sep 7, 2018 at 3:52 PM, Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Fri, Sep 07, 2018 at 07:14:20PM +0530, Srikar Dronamraju wrote:
> > * Peter Zijlstra <peterz@infradead.org> [2018-09-07 15:19:23]:
> >
> > > On Fri, Sep 07, 2018 at 06:26:49PM +0530, Srikar Dronamraju wrote:
> > >
> > > > Can you please pick
> > > >
> > > >
> > > > 1. 69bb3230297e881c797bbc4b3dbf73514078bc9d sched/numa: Stop multiple tasks
> > > > from moving to the cpu at the same time
> > > > 2. dc62cfdac5e5b7a61cd8a2bd4190e80b9bb408fc sched/numa: Avoid task migration
> > > > for small numa improvement
> > > > 3. 76e18a67cdd9e3609716c8a074c03168734736f9 sched/numa: Pass destination cpu as
> > > > a parameter to migrate_task_rq
> > > > 4.  489c19b440ebdbabffe530b9a41389d0a8b315d9 sched/numa: Reset scan rate
> > > > whenever task moves across nodes
> > > > 5.  b7e9ae1ae3825f35cd0f38f1f0c8e91ea145bc30 sched/numa: Limit the
> > > > conditions where scan period is reset
> > > >
> > > > from https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/commit/kernel/sched
> > >
> > > That is not a stable tree; the whole thing is re-generated from my quilt
> > > set every time I feel like it.
> > >
> > > It is likely those commit ids will no longer exist in a few hours.
> > >
> >
> > Okay, I will forward the relevant mails to Jirka.
>
> Or he can click on that link and find new IDs :-)