From: Jamie Lokier <jamie@shareable.org>
To: Paul Brook <paul@codesourcery.com>
Cc: kvm-devel <kvm-devel@lists.sourceforge.net>, qemu-devel@nongnu.org
Subject: Re: [kvm-devel] [Qemu-devel] [PATCH] QEMU: fsync AIO writes on flush request
Date: Sat, 29 Mar 2008 02:11:26 +0000 [thread overview]
Message-ID: <20080329021126.GD30219@shareable.org> (raw)
In-Reply-To: <200803290202.54431.paul@codesourcery.com>
Paul Brook wrote:
> > That'll depend on what kind of device is emulated. Does the SCSI
> > emulation handle multiple in-flight commands with any guarantee on
> > order?
>
> SCSI definitely allows (and we emulate) multiple in flight commands.
> I can't find any requirement that writes must complete before a
> subsequent SYNCHRONISE_CACHE. However I don't claim to know the spec
> that well,
Aren't there SCSI tagged barrier commands or something like that,
which allow a host to request ordering between commands?
> it's probably not a bad idea have them complete anyway. Preferably
> this would be a completely asynchronous operation. i.e. the sync
> command returns immediately, but only completes when all preceding
> writes have completed and been flushed to disk.
I agree, that seems the optimal implementation.
-- Jamie
next prev parent reply other threads:[~2008-03-29 2:11 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-28 15:05 [Qemu-devel] [PATCH] QEMU: fsync AIO writes on flush request Marcelo Tosatti
2008-03-28 15:07 ` Jamie Lokier
2008-03-28 16:31 ` [kvm-devel] " Marcelo Tosatti
2008-03-28 16:40 ` Paul Brook
2008-03-28 16:59 ` Marcelo Tosatti
2008-03-28 17:00 ` Paul Brook
2008-03-28 18:13 ` Marcelo Tosatti
2008-03-29 1:17 ` Jamie Lokier
2008-03-29 2:02 ` Paul Brook
2008-03-29 2:11 ` Jamie Lokier [this message]
2008-03-29 2:43 ` Paul Brook
2008-03-28 18:03 ` Jamie Lokier
2008-03-28 18:36 ` Marcelo Tosatti
2008-03-29 1:09 ` Jamie Lokier
2008-03-29 6:49 ` Marcelo Tosatti
2008-03-28 17:25 ` Ian Jackson
2008-03-28 19:11 ` [kvm-devel] " Marcelo Tosatti
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