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From: Fam Zheng <famz@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, kwolf@redhat.com,
	stefanha@redhat.com
Subject: Re: [Qemu-devel] [PATCH 05/18] block: change drain to look only at one child at a time
Date: Fri, 14 Oct 2016 18:12:26 +0800	[thread overview]
Message-ID: <20161014101226.GC14830@lemon> (raw)
In-Reply-To: <1476380062-18001-6-git-send-email-pbonzini@redhat.com>

On Thu, 10/13 19:34, Paolo Bonzini wrote:
> bdrv_requests_pending is checking children to also wait until internal
> requests (such as metadata writes) have completed.  However, checking
> children is in general overkill.  Children requests can be of two kinds:
> 
> - requests caused by an operation on bs, e.g. a bdrv_aio_write to bs
> causing a write to bs->file->bs.  In this case, the parent's in_flight
> count will always be incremented by at least one for every request in
> the child.

Isn't it "incremented by at least one" instead of "one for every request in the
child?

> 
> - asynchronous metadata writes or flushes.  Such writes can be started
> even if bs's in_flight count is zero, but not after the .bdrv_drain
> callback has been invoked.
> 
> This patch therefore changes bdrv_drain to finish I/O in the parent
> (after which the parent's in_flight will be locked to zero), call
> bdrv_drain (after which the parent will not generate I/O on the child
> anymore), and then wait for internal I/O in the children to complete.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Fam

  reply	other threads:[~2016-10-14 10:12 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-13 17:34 [Qemu-devel] [PATCH 00/18] dataplane: remove RFifoLock (including almost all previously sent patches) Paolo Bonzini
2016-10-13 17:34 ` [Qemu-devel] [PATCH 01/18] replication: interrupt failover if the main device is closed Paolo Bonzini
2016-10-13 17:34 ` [Qemu-devel] [PATCH 02/18] blockjob: introduce .drain callback for jobs Paolo Bonzini
2016-10-16 10:02   ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2016-10-17  7:53     ` [Qemu-devel] " Paolo Bonzini
2016-10-13 17:34 ` [Qemu-devel] [PATCH 03/18] mirror: use bdrv_drained_begin/bdrv_drained_end Paolo Bonzini
2016-10-14  9:43   ` Fam Zheng
2016-10-14 10:00     ` Paolo Bonzini
2016-10-13 17:34 ` [Qemu-devel] [PATCH 04/18] block: add BDS field to count in-flight requests Paolo Bonzini
2016-10-13 17:34 ` [Qemu-devel] [PATCH 05/18] block: change drain to look only at one child at a time Paolo Bonzini
2016-10-14 10:12   ` Fam Zheng [this message]
2016-10-13 17:34 ` [Qemu-devel] [PATCH 06/18] qed: Implement .bdrv_drain Paolo Bonzini
2016-10-14 10:33   ` Fam Zheng
2016-10-14 10:40     ` Paolo Bonzini
2016-10-13 17:34 ` [Qemu-devel] [PATCH 07/18] block: introduce bdrv_poll_while and bdrv_wakeup Paolo Bonzini
2016-10-14 10:42   ` Fam Zheng
2016-10-14 10:43     ` Paolo Bonzini
2016-10-16 10:25   ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2016-10-17  7:54     ` [Qemu-devel] " Paolo Bonzini
2016-10-13 17:34 ` [Qemu-devel] [PATCH 08/18] nfs: move nfs_set_events out of the while loops Paolo Bonzini
2016-10-16 10:37   ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2016-10-13 17:34 ` [Qemu-devel] [PATCH 09/18] nfs: use bdrv_poll_while and bdrv_wakeup Paolo Bonzini
2016-10-16 16:17   ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2016-10-13 17:34 ` [Qemu-devel] [PATCH 10/18] sheepdog: " Paolo Bonzini
2016-10-16 16:21   ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2016-10-13 17:34 ` [Qemu-devel] [PATCH 11/18] aio: introduce qemu_get_current_aio_context Paolo Bonzini
2016-10-16 16:28   ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2016-10-13 17:34 ` [Qemu-devel] [PATCH 12/18] iothread: detach all block devices before stopping them Paolo Bonzini
2016-10-14 14:50   ` Fam Zheng
2016-10-14 14:59     ` Paolo Bonzini
2016-10-13 17:34 ` [Qemu-devel] [PATCH 13/18] replication: pass BlockDriverState to reopen_backing_file Paolo Bonzini
2016-10-16 16:31   ` Stefan Hajnoczi
2016-10-13 17:34 ` [Qemu-devel] [PATCH 14/18] block: prepare bdrv_reopen_multiple to release AioContext Paolo Bonzini
2016-10-16 16:32   ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2016-10-13 17:34 ` [Qemu-devel] [PATCH 15/18] block: only call aio_poll on the current thread's AioContext Paolo Bonzini
2016-10-14 14:55   ` Fam Zheng
2016-10-16 16:40   ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2016-10-17  8:04     ` [Qemu-devel] " Paolo Bonzini
2016-10-18 10:10       ` Stefan Hajnoczi
2016-10-13 17:34 ` [Qemu-devel] [PATCH 16/18] iothread: release AioContext around aio_poll Paolo Bonzini
2016-10-13 17:34 ` [Qemu-devel] [PATCH 17/18] qemu-thread: introduce QemuRecMutex Paolo Bonzini
2016-10-13 17:34 ` [Qemu-devel] [PATCH 18/18] aio: convert from RFifoLock to QemuRecMutex Paolo Bonzini
2016-10-16 16:43   ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2016-10-17  8:58 ` [Qemu-devel] [PATCH 00/18] dataplane: remove RFifoLock (including almost all previously sent patches) Christian Borntraeger
2016-10-17  9:17   ` Paolo Bonzini

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