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From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Mon, 19 Mar 2012 17:05:33 -0700
Message-ID: <CA+55aFwa-81x2Dysk8WS8ez2WkYSbaQDyQvpH0qE7fGJgxTbUQ@mail.gmail.com>
Subject: Re: [RFC][PATCH 00/26] sched/numa
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To: Ingo Molnar <mingo@kernel.org>
Cc: Christoph Lameter <cl@linux.com>, Andrea Arcangeli <aarcange@redhat.com>, Peter Zijlstra <a.p.zijlstra@chello.nl>, Avi Kivity <avi@redhat.com>, Andrew Morton <akpm@linux-foundation.org>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>, Paul Turner <pjt@google.com>, Suresh Siddha <suresh.b.siddha@intel.com>, Mike Galbraith <efault@gmx.de>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Lai Jiangshan <laijs@cn.fujitsu.com>, Dan Smith <danms@us.ibm.com>, Bharata B Rao <bharata.rao@gmail.com>, Lee Schermerhorn <Lee.Schermerhorn@hp.com>, Rik van Riel <riel@redhat.com>, Johannes Weiner <hannes@cmpxchg.org>, linux-kernel@vger.kernel.org, linux-mm@kvack.org

On Mon, Mar 19, 2012 at 1:28 PM, Ingo Molnar <mingo@kernel.org> wrote:
>
> That having said PeterZ's numbers showed some pretty good
> improvement for the streams workload:
>
> =A0before: 512.8M
> =A0after: 615.7M
>
> i.e. a +20% improvement on a not very heavily NUMA box.

Well, streams really isn't a very interesting benchmark. It's the
traditional single-threaded cpu-only thing that just accesses things
linearly, and I'm not convinced the numbers should be taken to mean
anything at all.

The HPC people want to multi-thread things these days, and "cpu/memory
affinity" is a lot less clear then.

So I can easily imagine that the performance improvement is real, but
I really don't think "streams improves by X %" is all that
interesting. Are there any more relevant loads that actually matter to
people that we could show improvement on?

                     Linus

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