From: Stefan Hajnoczi <stefanha@gmail.com>
To: Yaodong Yang <yaodong.yangy@icloud.com>
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] questions about the bdrv_co_do_readv()
Date: Tue, 27 Aug 2013 09:45:07 +0200 [thread overview]
Message-ID: <20130827074507.GC24247@stefanha-thinkpad.redhat.com> (raw)
In-Reply-To: <7453899A-FDF5-4290-82FA-3EFDC4DD8EA4@icloud.com>
On Mon, Aug 26, 2013 at 09:59:51PM -0500, Yaodong Yang wrote:
> In sum, the bdrv_co_do_readv() seems to be executed inside two thread, the migration thread and native iothread. Both of them executed the function twice for a single request. Could someone explain it for me ? I appreciate it very much!
Did you check the bdrv_co_readv(bs=...) argument? The calls may be
referring to two different BlockDriverState instances.
A raw image file looks like this:
BDS#1 (block/raw.c)
->backing_hd = NULL
->file = BDS#2
BDS#2 (block/raw-posix.c)
With qcow2 and no backing file you would have something like this:
BDS#1 (block/qcow2.c)
->backing_hd = NULL
->file = BDS#2
BDS#2 (block/raw-posix.c)
Expect to see calls forwarded from BDS#1 to BDS#2.
Stefan
next prev parent reply other threads:[~2013-08-27 7:45 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-27 2:59 [Qemu-devel] questions about the bdrv_co_do_readv() Yaodong Yang
2013-08-27 7:45 ` Stefan Hajnoczi [this message]
2013-08-27 22:55 ` Yaodong Yang
2013-08-28 7:58 ` Stefan Hajnoczi
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