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Re: [regression v4.0-rc1] mm: IPIs from TLB flushes causing significant

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: [regression v4.0-rc1] mm: IPIs from TLB flushes causing significant performance degradation.
From: Ingo Molnar <mingo@xxxxxxxxxx>
Date: Thu, 5 Mar 2015 00:35:45 +0100
Cc: Mel Gorman <mgorman@xxxxxxx>, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, Matt B <jackdachef@xxxxxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, linux-mm <linux-mm@xxxxxxxxx>, xfs@xxxxxxxxxxx
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Sender: Ingo Molnar <mingo.kernel.org@xxxxxxxxx>
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* Dave Chinner <david@xxxxxxxxxxxxx> wrote:

> > After going through the series again, I did not spot why there is 
> > a difference. It's functionally similar and I would hate the 
> > theory that this is somehow hardware related due to the use of 
> > bits it takes action on.
> 
> I doubt it's hardware related - I'm testing inside a VM, [...]

That might be significant, I doubt Mel considered KVM's interpretation 
of pte details?

Thanks,

        Ingo

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