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Re: [Qemu-devel] qemu-img convert cache mode for source
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] qemu-img convert cache mode for source |
Date: |
Tue, 4 Mar 2014 10:24:56 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Mon, Mar 03, 2014 at 01:20:21PM +0100, Peter Lieven wrote:
> On 03.03.2014 13:03, Stefan Hajnoczi wrote:
> >So what is the actual performance problem you are trying to solve and
> >what benchmark output are you getting when you compare with
> >FADV_DONTNEED against without FADV_DONTNEED?
> I found the performance to be identical. For the problem see below please.
> >
> >I think there's a danger that the discussion will go around in circles.
> >Please post the performance results that kicked off this whole effort
> >and let's focus on the data. That way it's much easier to evaluate what
> >changes to QEMU are a win and which are not necessary.
> I found that under memory pressure situations the increasing buffers
> leads to vserver memory being swapped out. This caused trouble
> especially in overcommit scenarios (where all memory is backed by
> swap).
I think the general idea is qemu-img should not impact running guests,
even on a heavily loaded machine. But again, this needs to be discussed
using concrete benchmarks with configurations and results posted to the
list.
Stefan
- Re: [Qemu-devel] qemu-img convert cache mode for source, Kevin Wolf, 2014/03/03
- Re: [Qemu-devel] qemu-img convert cache mode for source, Kevin Wolf, 2014/03/03
- Re: [Qemu-devel] qemu-img convert cache mode for source, Stefan Hajnoczi, 2014/03/03
- Re: [Qemu-devel] qemu-img convert cache mode for source, Peter Lieven, 2014/03/03
- Re: [Qemu-devel] qemu-img convert cache mode for source,
Stefan Hajnoczi <=
- Re: [Qemu-devel] qemu-img convert cache mode for source, Peter Lieven, 2014/03/05
- Re: [Qemu-devel] qemu-img convert cache mode for source, Marcus, 2014/03/05
- Re: [Qemu-devel] qemu-img convert cache mode for source, Peter Lieven, 2014/03/05
- Re: [Qemu-devel] qemu-img convert cache mode for source, Marcus, 2014/03/05
- Re: [Qemu-devel] qemu-img convert cache mode for source, Peter Lieven, 2014/03/05
- Re: [Qemu-devel] qemu-img convert cache mode for source, Stefan Hajnoczi, 2014/03/06
- Re: [Qemu-devel] qemu-img convert cache mode for source, Peter Lieven, 2014/03/06
- Re: [Qemu-devel] qemu-img convert cache mode for source, Stefan Hajnoczi, 2014/03/06
- Re: [Qemu-devel] qemu-img convert cache mode for source, Paolo Bonzini, 2014/03/06
- Re: [Qemu-devel] qemu-img convert cache mode for source, Liguori, Anthony, 2014/03/06