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Date: Thu, 31 May 2018 11:26:19 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Subhra Mazumdar <subhra.mazumdar@oracle.com>
Cc: linux-kernel@vger.kernel.org, mingo@redhat.com,
        daniel.lezcano@linaro.org, steven.sistare@oracle.com,
        dhaval.giani@oracle.com, rohit.k.jain@oracle.com,
        Mike Galbraith <umgwanakikbuti@gmail.com>,
        Matt Fleming <matt@codeblueprint.co.uk>
Subject: Re: [PATCH 1/3] sched: remove select_idle_core() for scalability
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On Wed, May 30, 2018 at 03:08:21PM -0700, Subhra Mazumdar wrote:
> I tested with FOLD+AGE+ONCE+PONIES+PONIES2 shift=0 vs baseline but see some
> regression for hackbench and uperf:

I'm not seeing a hackbench regression myself, but I let it run a whole
lot of stuff over-night and I do indeed see some pain points, including
sysbench-mysql and some schbench results.

> I have a patch which is much smaller but seems to work well so far for both
> x86 and SPARC across benchmarks I have run so far. It keeps the idle cpu
> search between 1 core and 2 core amount of cpus and also puts a new
> sched feature of doing idle core search or not. It can be on by default but
> for workloads (like Oracle DB on x86) we can turn it off. I plan to send
> that after some more testing.

Sure thing..