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Message-ID: <20131220111303.GZ11295@suse.de>
Date: Fri, 20 Dec 2013 11:13:03 +0000
From: Mel Gorman <mgorman@...e.de>
To: Ingo Molnar <mingo@...nel.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
Alex Shi <alex.shi@...aro.org>,
Thomas Gleixner <tglx@...utronix.de>,
Andrew Morton <akpm@...ux-foundation.org>,
Fengguang Wu <fengguang.wu@...el.com>,
H Peter Anvin <hpa@...or.com>, Linux-X86 <x86@...nel.org>,
Linux-MM <linux-mm@...ck.org>,
LKML <linux-kernel@...r.kernel.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH 0/4] Fix ebizzy performance regression due to X86 TLB
range flush v2
On Thu, Dec 19, 2013 at 05:49:25PM +0100, Ingo Molnar wrote:
>
> * Mel Gorman <mgorman@...e.de> wrote:
>
> > [...]
> >
> > Because we lack data on TLB range flush distributions I think we
> > should still go with the conservative choice for the TLB flush
> > shift. The worst case is really bad here and it's painfully obvious
> > on ebizzy.
>
> So I'm obviously much in favor of this - I'd in fact suggest making
> the conservative choice on _all_ CPU models that have aggressive TLB
> range values right now, because frankly the testing used to pick those
> values does not look all that convincing to me.
>
I think the choices there are already reasonably conservative. I'd be
reluctant to support merging a patch that made a choice on all CPU models
without having access to the machines to run tests on. I don't see the
Intel people volunteering to do the necessary testing.
--
Mel Gorman
SUSE Labs
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