From: Paolo Bonzini <pbonzini@redhat.com>
To: Liu Yuan <namei.unix@gmail.com>
Cc: Kevin Wolf <kwolf@redhat.com>,
Stefan Hajnoczi <stefanha@gmail.com>,
qemu-devel@nongnu.org,
MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>
Subject: Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics
Date: Wed, 09 Jan 2013 11:40:51 +0100 [thread overview]
Message-ID: <50ED4933.3040001@redhat.com> (raw)
In-Reply-To: <50ED4829.1070302@gmail.com>
Il 09/01/2013 11:36, Liu Yuan ha scritto:
>> But why is it useful to force-disable writeback caching? Do you have
>> > any performance numbers?
> This is not related to performance. What I want is to allow users to
> choose Sheepdog cache mode (writethrough/writeback/directio) from cache=xxx.
>
> Obviously writeback mode show much better write performance over
> writethrough cache in Sheepdog. NOTE: writethrough cache in Sheepdog is
> a readonly cache which is always consistent with cluster data thus need
> no flush at all. This is to boost read performance for read intensive
> Guest over Sheepdog iamges.
Ok, so the questions are (compared to older QEMU's writethrough mode):
1) how slower is QEMU's emulated-writethrough mode for writes, due to
the extra requests?
2) how slower is QEMU's writeback mode for reads, due to the different
structure of the cache?
Paolo
next prev parent reply other threads:[~2013-01-09 10:41 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-19 18:29 [Qemu-devel] [PATCH] sheepdog: implement direct write semantics Liu Yuan
2012-12-25 7:47 ` MORITA Kazutaka
2012-12-25 8:26 ` Liu Yuan
2012-12-25 8:45 ` Liu Yuan
2013-01-03 13:43 ` Liu Yuan
2013-01-04 16:38 ` Stefan Hajnoczi
2013-01-05 4:40 ` Liu Yuan
2013-01-05 5:29 ` Liu Yuan
2013-01-05 7:56 ` Liu Yuan
2013-01-07 12:31 ` Stefan Hajnoczi
2013-01-08 5:28 ` Liu Yuan
2013-01-07 13:23 ` Kevin Wolf
2013-01-08 5:42 ` Liu Yuan
2013-01-08 9:40 ` Stefan Hajnoczi
2013-01-08 9:45 ` Liu Yuan
2013-01-08 10:00 ` Kevin Wolf
2013-01-08 10:39 ` Liu Yuan
2013-01-08 10:51 ` Kevin Wolf
2013-01-08 11:08 ` Liu Yuan
2013-01-08 11:19 ` Kevin Wolf
2013-01-08 11:35 ` Liu Yuan
2013-01-08 12:12 ` Kevin Wolf
2013-01-08 13:18 ` Liu Yuan
2013-01-08 13:23 ` Liu Yuan
2013-01-09 10:25 ` Paolo Bonzini
2013-01-09 10:36 ` Liu Yuan
2013-01-09 10:40 ` Paolo Bonzini [this message]
2013-01-09 10:46 ` Liu Yuan
2013-01-09 10:58 ` Liu Yuan
2013-01-09 11:10 ` Paolo Bonzini
2013-01-09 12:07 ` Liu Yuan
2013-01-09 12:10 ` Liu Yuan
2013-01-09 12:16 ` Liu Yuan
2013-01-09 12:42 ` Kevin Wolf
2013-01-09 13:04 ` Liu Yuan
2013-01-09 15:10 ` Paolo Bonzini
2013-01-10 5:38 ` Liu Yuan
2013-01-11 7:52 ` MORITA Kazutaka
2013-01-11 8:07 ` Liu Yuan
2013-01-11 9:00 ` Paolo Bonzini
2013-01-11 9:04 ` Liu Yuan
2013-01-11 9:34 ` Paolo Bonzini
2013-01-11 9:38 ` Liu Yuan
2013-01-11 9:40 ` Paolo Bonzini
2013-01-11 9:32 ` Kevin Wolf
2013-01-10 15:25 ` Jamie Lokier
2013-01-10 15:31 ` Paolo Bonzini
2013-01-10 17:22 ` Jamie Lokier
2013-01-09 11:10 ` Kevin Wolf
2013-01-09 10:23 ` Paolo Bonzini
2013-01-10 15:12 ` Jamie Lokier
2013-01-10 15:21 ` Kevin Wolf
2013-01-10 8:03 ` [Qemu-devel] [PATCH v2] " Liu Yuan
2013-01-10 9:04 ` Stefan Hajnoczi
2013-01-11 7:35 ` MORITA Kazutaka
2013-01-11 9:23 ` Kevin Wolf
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