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Date: Tue, 12 Mar 2013 16:12:18 +0100
From: Stefan Hajnoczi <stefanha@gmail.com>
Message-ID: <20130312151218.GA21551@stefanha-thinkpad.redhat.com>
References: <513DDFA3.1020308@dlhnet.de>
	<20130312083515.GA18302@stefanha-thinkpad.redhat.com>
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Subject: Re: [Qemu-devel] [RFC] find_next_bit optimizations
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To: Peter Lieven <pl@dlhnet.de>
Cc: Orit Wasserman <owasserm@redhat.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, Corentin Chary <corentin.chary@gmail.com>, Paolo Bonzini <pbonzini@redhat.com>

On Tue, Mar 12, 2013 at 09:41:04AM +0100, Peter Lieven wrote:
> 
> Am 12.03.2013 um 09:35 schrieb Stefan Hajnoczi <stefanha@gmail.com>:
> 
> > On Mon, Mar 11, 2013 at 02:44:03PM +0100, Peter Lieven wrote:
> >> I ever since had a few VMs which are very hard to migrate because of a lot of memory I/O. I found that finding the next dirty bit
> >> seemed to be one of the culprits (apart from removing locking which Paolo is working on).
> >> 
> >> I have to following proposal which seems to help a lot in my case. Just wanted to have some feedback.
> > 
> > Hi Peter,
> > Do you have any performance numbers for this patch?  I'm just curious
> > how big the win is.
> 
> Hi Stefan,
> 
> please see my recent email to the list with the final patch.
> The win is up to 100%. Worst case execution time (whole
> array is zero) is halved on x86_64.

Thanks!

Stefan