From: RW <kvm@tauceti.net>
To: Thomas Beinicke <thomas.beinicke@fsd-web.de>
Cc: KVM mailing list <kvm@vger.kernel.org>
Subject: Re: repeatable hang with loop mount and heavy IO in guest
Date: Thu, 21 Jan 2010 22:36:12 +0100 [thread overview]
Message-ID: <4B58C8CC.4000103@tauceti.net> (raw)
In-Reply-To: <201001212208.48951.thomas.beinicke@fsd-web.de>
No sorry, I haven't any performance data with noop. I even don't
have had a crash. BUT I've experienced serve I/O degradation
with noop. Once I've written a big chunk of data (e.g. a simple
rsync -av /usr /opt) with noop it works for a while and
after a few seconds I saw heavy writes which made the
VM virtually unusable. As far as I remember it was kjournald
which cases the writes.
I've written a mail to the list some months ago with some benchmarks:
http://article.gmane.org/gmane.comp.emulators.kvm.devel/41112/match=benchmark
There're some I/O benchmarks in there. You can't get the graphs
currently since tauceti.net is offline until monday. I haven't
tested noop in these benchmarks because of the problems
mentioned above. But it compares deadline and cfq a little bit
on a HP DL 380 G6 server.
Robert
On 01/21/10 22:08, Thomas Beinicke wrote:
> On Thursday 21 January 2010 21:08:38 RW wrote:
>> Some months ago I also thought elevator=noop should be a good idea.
>> But it isn't. It works good as long as you only do short IO requests.
>> Try using deadline in host and guest.
>>
>> Robert
>
> @Robert: I've been using noop on all of my KVMs and didn't have any problems
> so far, never had any crash too.
> Do you have any performance data or comparisons between noop and deadline io
> schedulers?
>
> Cheers,
>
> Thomas
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next prev parent reply other threads:[~2010-01-21 21:32 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-21 17:26 repeatable hang with loop mount and heavy IO in guest Antoine Martin
2010-01-21 20:08 ` RW
2010-01-21 21:08 ` Thomas Beinicke
2010-01-21 21:36 ` RW [this message]
2010-01-22 7:57 ` Michael Tokarev
2010-01-22 18:28 ` repeatable hang with loop mount and heavy IO in guest [SOLVED] Antoine Martin
2010-01-22 19:15 ` repeatable hang with loop mount and heavy IO in guest [NOT SOLVED] Antoine Martin
2010-01-24 11:23 ` Antoine Martin
2010-02-03 19:28 ` Antoine Martin
2010-02-26 17:38 ` repeatable hang with loop mount and heavy IO in guest Antoine Martin
2010-05-21 9:38 ` repeatable hang with loop mount and heavy IO in guest (now in host - not KVM then..) Antoine Martin
2010-05-22 18:10 ` Jim Paris
2010-05-22 19:33 ` Antoine Martin
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