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Date: Tue, 3 Oct 2017 10:39:32 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Rik van Riel <riel@redhat.com>,
        Eric Farman <farman@linux.vnet.ibm.com>,
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        "KVM-ML (kvm@vger.kernel.org)" <kvm@vger.kernel.org>,
        vcaputo@pengaru.com, Matthew Rosato <mjrosato@linux.vnet.ibm.com>
Subject: Re: sysbench throughput degradation in 4.13+
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On Mon, Oct 02, 2017 at 11:53:12PM +0100, Matt Fleming wrote:
> On Wed, 27 Sep, at 01:58:20PM, Rik van Riel wrote:
> > 
> > I like the simplicity of your approach!  I hope it does not break
> > stuff like netperf...
> > 
> > I have been working on the patch below, which is much less optimistic
> > about when to do an affine wakeup than before.
> 
> Running netperf for this patch and Peter's patch shows that Peter's
> comes out on top, with scores pretty close to v4.12 in most places on
> my 2-NUMA node 48-CPU Xeon box.
> 
> I haven't dug any further into why v4.13-peterz+ is worse than v4.12,
> but I will next week.

So I was waiting for Rik, who promised to run a bunch of NUMA workloads
over the weekend.

The trivial thing regresses a wee bit on the overloaded case, I've not
yet tried to fix it.