From: Kevin Wolf <kwolf@redhat.com>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Anthony Liguori <aliguori@us.ibm.com>,
pingfank@linux.vnet.ibm.com, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [RFC 00/13] aio: drop io_flush()
Date: Fri, 12 Apr 2013 10:02:02 +0200 [thread overview]
Message-ID: <20130412080202.GB3426@dhcp-200-207.str.redhat.com> (raw)
In-Reply-To: <1365695085-27970-1-git-send-email-stefanha@redhat.com>
Am 11.04.2013 um 17:44 hat Stefan Hajnoczi geschrieben:
> Here's my entry to the "let's get rid of io_flush()" effort. It's based on
> Paolo's insight about bdrv_drain_all() that the block layer already has a
> tracked_requests list. io_flush() is redundant since the block layer already
> knows if requests are pending.
Except when there are requests that don't come from the guest, but are
issued internally. In this case, block.c doesn't know about them, but
only the block driver does, so we need a .bdrv_drain callback to tell
the block layer about these.
The one specific case that comes to mind is the QED timer for resetting
the dirty bit. I think you need to have the .bdrv_drain callback before
you can start ignoring .io_flush.
Kevin
next prev parent reply other threads:[~2013-04-12 8:02 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-11 15:44 [Qemu-devel] [RFC 00/13] aio: drop io_flush() Stefan Hajnoczi
2013-04-11 15:44 ` [Qemu-devel] [RFC 01/13] block: stop relying on io_flush() in bdrv_drain_all() Stefan Hajnoczi
2013-04-11 15:44 ` [Qemu-devel] [RFC 02/13] dataplane/virtio-blk: check exit conditions before aio_poll() Stefan Hajnoczi
2013-04-11 15:44 ` [Qemu-devel] [RFC 03/13] aio: stop using .io_flush() Stefan Hajnoczi
2013-04-11 15:44 ` [Qemu-devel] [RFC 04/13] block/curl: drop curl_aio_flush() Stefan Hajnoczi
2013-04-11 15:44 ` [Qemu-devel] [RFC 05/13] block/gluster: drop qemu_gluster_aio_flush_cb() Stefan Hajnoczi
2013-04-11 15:44 ` [Qemu-devel] [RFC 06/13] block/iscsi: drop iscsi_process_flush() Stefan Hajnoczi
2013-04-11 15:44 ` [Qemu-devel] [RFC 07/13] block/linux-aio: drop qemu_laio_completion_cb() Stefan Hajnoczi
2013-04-11 15:44 ` [Qemu-devel] [RFC 08/13] block/nbd: drop nbd_have_request() Stefan Hajnoczi
2013-04-11 15:44 ` [Qemu-devel] [RFC 09/13] block/rbd: drop qemu_rbd_aio_flush_cb() Stefan Hajnoczi
2013-04-11 15:44 ` [Qemu-devel] [RFC 10/13] block/sheepdog: drop have_co_req() and aio_flush_request() Stefan Hajnoczi
2013-04-11 15:44 ` [Qemu-devel] [RFC 11/13] dataplane/virtio-blk: drop flush_true() and flush_io() Stefan Hajnoczi
2013-04-11 15:44 ` [Qemu-devel] [RFC 12/13] thread-pool: drop thread_pool_active() Stefan Hajnoczi
2013-04-11 15:44 ` [Qemu-devel] [RFC 13/13] aio: drop io_flush argument Stefan Hajnoczi
2013-04-12 8:02 ` Kevin Wolf [this message]
2013-04-12 9:49 ` [Qemu-devel] [RFC 00/13] aio: drop io_flush() Stefan Hajnoczi
2013-04-12 10:04 ` Kevin Wolf
2013-04-12 10:27 ` Paolo Bonzini
2013-04-12 12:06 ` Stefan Hajnoczi
2013-04-12 12:22 ` Kevin Wolf
2013-04-12 13:41 ` Stefan Hajnoczi
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