From: Paolo Bonzini <pbonzini@redhat.com>
To: Stefan Hajnoczi <stefanha@redhat.com>, Fam Zheng <famz@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>,
qemu-block@nongnu.org, Peter Lieven <pl@kamp.de>,
qemu-devel@nongnu.org, Ronnie Sahlberg <ronniesahlberg@gmail.com>
Subject: Re: [Qemu-devel] [PATCH v2 8/9] block: Introduce BlockDriver.bdrv_drain callback
Date: Thu, 5 Nov 2015 18:11:55 +0100 [thread overview]
Message-ID: <563B8DDB.1000304@redhat.com> (raw)
In-Reply-To: <20151105163539.GB1702@stefanha-x1.localdomain>
On 05/11/2015 17:35, Stefan Hajnoczi wrote:
>> > void bdrv_drain(BlockDriverState *bs)
>> > {
>> > + BdrvChild *child;
>> > bool busy = true;
>> >
>> > + if (bs->drv && bs->drv->bdrv_drain) {
>> > + bs->drv->bdrv_drain(bs);
>> > + }
>> > + QLIST_FOREACH(child, &bs->children, next) {
>> > + bdrv_drain(child->bs);
>> > + }
>> > while (busy) {
>> > /* Keep iterating */
>> > bdrv_flush_io_queue(bs);
> Recursing calls aio_poll() once for each BDS node and I think it's not
> necessary and could be a performance problem.
Indeed, only the call to bs->drv->bdrv_drain should be done recursively.
Paolo
next prev parent reply other threads:[~2015-11-05 17:12 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-29 2:14 [Qemu-devel] [PATCH v2 0/9] block: Fixes for bdrv_drain Fam Zheng
2015-10-29 2:14 ` [Qemu-devel] [PATCH v2 1/9] block: Add more types for tracked request Fam Zheng
2015-10-29 2:14 ` [Qemu-devel] [PATCH v2 2/9] block: Track flush requests Fam Zheng
2015-10-29 2:14 ` [Qemu-devel] [PATCH v2 3/9] block: Track discard requests Fam Zheng
2015-10-29 2:14 ` [Qemu-devel] [PATCH v2 4/9] iscsi: Emulate commands in iscsi_aio_ioctl as iscsi_ioctl Fam Zheng
2015-10-29 2:14 ` [Qemu-devel] [PATCH v2 5/9] block: Add ioctl parameter fields to BlockRequest Fam Zheng
2015-10-29 2:14 ` [Qemu-devel] [PATCH v2 6/9] block: Emulate bdrv_ioctl with bdrv_aio_ioctl and track both Fam Zheng
2015-11-05 15:59 ` Stefan Hajnoczi
2015-10-29 2:14 ` [Qemu-devel] [PATCH v2 7/9] block: Drop BlockDriver.bdrv_ioctl Fam Zheng
2015-10-29 2:14 ` [Qemu-devel] [PATCH v2 8/9] block: Introduce BlockDriver.bdrv_drain callback Fam Zheng
2015-11-05 16:35 ` Stefan Hajnoczi
2015-11-05 17:11 ` Paolo Bonzini [this message]
2015-10-29 2:14 ` [Qemu-devel] [PATCH v2 9/9] qed: Implement .bdrv_drain Fam Zheng
2015-11-03 12:19 ` [Qemu-devel] [PATCH v2 0/9] block: Fixes for bdrv_drain Kevin Wolf
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