From: Avi Kivity <avi@redhat.com>
To: Kevin Wolf <kwolf@redhat.com>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [RFC] block-queue: Delay and batch metadata writes
Date: Mon, 20 Sep 2010 17:33:35 +0200 [thread overview]
Message-ID: <4C977ECF.4000907@redhat.com> (raw)
In-Reply-To: <4C9778EC.9060704@redhat.com>
On 09/20/2010 05:08 PM, Kevin Wolf wrote:
> >
> > Let's expand it a bit more:
> >
> > 1. Update refcount table
> > 2. bdrv_flush
> > 3. Update L2 entry
> > 4. Write data to disk
> > 5. Report write complete
> >
> > I'm struggling to understand how a thread helps out.
>
> This sequence becomes:
>
> 1. Update refcount table
> 2. Write data to disk
> 3. Report write complete
>
> And only later:
>
> 4. Update L2 entry
> 5. bdrv_flush (possibly merged with other flushes)
>
The L2 update needs to happen after we're sure the refcount update is
stable, so need a bdrv_flush between them.
Still, the basic idea looks sound. You can do many refcount updates,
flush, many L2 updates, flush.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2010-09-20 15:33 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-20 13:56 [Qemu-devel] [RFC] block-queue: Delay and batch metadata writes Kevin Wolf
2010-09-20 14:31 ` Anthony Liguori
2010-09-20 14:56 ` Anthony Liguori
2010-09-20 15:33 ` Kevin Wolf
2010-09-20 15:48 ` Anthony Liguori
2010-09-20 15:08 ` Kevin Wolf
2010-09-20 15:33 ` Avi Kivity [this message]
2010-09-20 15:38 ` Avi Kivity
2010-09-20 15:46 ` Kevin Wolf
2010-09-20 15:40 ` Anthony Liguori
2010-09-20 15:55 ` Kevin Wolf
2010-09-20 16:34 ` Anthony Liguori
2010-09-20 15:51 ` Anthony Liguori
2010-09-20 16:05 ` Avi Kivity
2010-09-21 9:13 ` Kevin Wolf
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