From: Anthony Liguori <aliguori@linux.vnet.ibm.com>
To: Avi Kivity <avi@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Christoph Hellwig <hch@lst.de>,
Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>,
qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] Re: [PATCH v2 6/7] qed: Read/write support
Date: Wed, 13 Oct 2010 09:11:49 -0500 [thread overview]
Message-ID: <4CB5BE25.3060502@linux.vnet.ibm.com> (raw)
In-Reply-To: <4CB5BDD1.8050409@redhat.com>
>> > >
>> > >That means we can maintain the physical size without introducing
>> > >additional fsync()s in the allocation path. Since we're already
>> > >writing out the header anyway, the write operation is basically
>> > >free too.
>> >
>> > I don't see how it is free. It's an extra write. The good news is
>> > that it's very easy to amortize.
>>
>> We only need to update the header field on disk when we're already
>> updating the header, so it's not even an extra write operation.
>
> Why would you ever update the header, apart from relocating L1 for
> some reason?
To update the L1/L2 tables clean bit. That's what prevents a check in
the normal case where you have a clean shutdown.
Regards,
Anthony Liguori
next prev parent reply other threads:[~2010-10-13 14:13 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-08 15:48 [Qemu-devel] [PATCH v2 0/7] qed: Add QEMU Enhanced Disk format Stefan Hajnoczi
2010-10-08 15:48 ` [Qemu-devel] [PATCH v2 1/7] qcow2: Make get_bits_from_size() common Stefan Hajnoczi
2010-10-08 18:01 ` [Qemu-devel] " Anthony Liguori
2010-10-08 15:48 ` [Qemu-devel] [PATCH v2 2/7] cutils: Add bytes_to_str() to format byte values Stefan Hajnoczi
2010-10-11 11:09 ` [Qemu-devel] " Kevin Wolf
2010-10-13 9:15 ` [Qemu-devel] " Markus Armbruster
2010-10-13 9:28 ` Kevin Wolf
2010-10-13 10:58 ` Stefan Hajnoczi
2010-10-13 10:25 ` [Qemu-devel] " Avi Kivity
2010-10-08 15:48 ` [Qemu-devel] [PATCH v2 3/7] docs: Add QED image format specification Stefan Hajnoczi
2010-10-10 9:20 ` [Qemu-devel] " Avi Kivity
2010-10-11 10:09 ` Stefan Hajnoczi
2010-10-11 13:04 ` Avi Kivity
2010-10-11 13:42 ` Stefan Hajnoczi
2010-10-11 13:44 ` Avi Kivity
2010-10-11 14:06 ` Stefan Hajnoczi
2010-10-11 14:12 ` Avi Kivity
2010-10-11 15:02 ` Anthony Liguori
2010-10-11 15:24 ` Avi Kivity
2010-10-11 15:41 ` Anthony Liguori
2010-10-11 15:47 ` Avi Kivity
2010-10-11 14:54 ` Anthony Liguori
2010-10-11 14:58 ` Avi Kivity
2010-10-11 15:49 ` Anthony Liguori
2010-10-11 16:02 ` Avi Kivity
2010-10-11 16:10 ` Anthony Liguori
2010-10-12 10:25 ` Avi Kivity
2010-10-11 13:58 ` Kevin Wolf
2010-10-11 15:30 ` Stefan Hajnoczi
2010-10-11 15:39 ` Avi Kivity
2010-10-11 15:46 ` Stefan Hajnoczi
2010-10-11 16:18 ` Anthony Liguori
2010-10-11 17:14 ` Anthony Liguori
2010-10-12 8:07 ` Kevin Wolf
2010-10-12 13:16 ` Stefan Hajnoczi
2010-10-12 13:32 ` Anthony Liguori
2010-10-11 15:50 ` Kevin Wolf
2010-10-08 15:48 ` [Qemu-devel] [PATCH v2 4/7] qed: Add QEMU Enhanced Disk image format Stefan Hajnoczi
2010-10-11 15:16 ` [Qemu-devel] " Kevin Wolf
2010-10-08 15:48 ` [Qemu-devel] [PATCH v2 5/7] qed: Table, L2 cache, and cluster functions Stefan Hajnoczi
2010-10-12 14:44 ` [Qemu-devel] " Kevin Wolf
2010-10-13 13:41 ` Stefan Hajnoczi
2010-10-08 15:48 ` [Qemu-devel] [PATCH v2 6/7] qed: Read/write support Stefan Hajnoczi
2010-10-10 9:10 ` [Qemu-devel] " Avi Kivity
2010-10-11 10:37 ` Stefan Hajnoczi
2010-10-11 13:10 ` Avi Kivity
2010-10-11 13:55 ` Stefan Hajnoczi
2010-10-11 14:57 ` Anthony Liguori
2010-10-12 15:08 ` Kevin Wolf
2010-10-12 15:22 ` Anthony Liguori
2010-10-12 15:39 ` Kevin Wolf
2010-10-12 15:59 ` Stefan Hajnoczi
2010-10-12 16:16 ` Anthony Liguori
2010-10-12 16:21 ` Avi Kivity
2010-10-13 12:13 ` Stefan Hajnoczi
2010-10-13 13:07 ` Kevin Wolf
2010-10-13 13:24 ` Anthony Liguori
2010-10-13 13:50 ` Avi Kivity
2010-10-13 14:07 ` Stefan Hajnoczi
2010-10-13 14:08 ` Anthony Liguori
2010-10-13 14:10 ` Avi Kivity
2010-10-13 14:11 ` Anthony Liguori [this message]
2010-10-13 14:16 ` Avi Kivity
2010-10-13 14:53 ` Anthony Liguori
2010-10-13 15:08 ` Avi Kivity
2010-10-13 15:42 ` Anthony Liguori
2010-10-14 11:06 ` Stefan Hajnoczi
2010-10-13 14:10 ` Anthony Liguori
2010-10-08 15:48 ` [Qemu-devel] [PATCH v2 7/7] qed: Consistency check support Stefan Hajnoczi
2010-10-11 13:21 ` [Qemu-devel] Re: [PATCH v2 0/7] qed: Add QEMU Enhanced Disk format Kevin Wolf
2010-10-11 15:37 ` Stefan Hajnoczi
2010-10-16 7:51 ` [Qemu-devel] " Stefan Hajnoczi
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