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From: Paolo Bonzini <pbonzini@redhat.com>
To: Ming Lei <ming.lei@canonical.com>
Cc: Kevin Wolf <kwolf@redhat.com>,
	Peter Maydell <peter.maydell@linaro.org>,
	Fam Zheng <famz@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	qemu-devel <qemu-devel@nongnu.org>,
	Stefan Hajnoczi <stefanha@redhat.com>
Subject: Re: [Qemu-devel] [PATCH 2/2] virtio-blk: dataplane: notify guest as a batch
Date: Fri, 04 Jul 2014 17:48:07 +0200	[thread overview]
Message-ID: <53B6CCB7.2070009@redhat.com> (raw)
In-Reply-To: <CACVXFVO0gJG0AG+K0rK7xBveUjRmVj6gUUC_QWdJ+C2Y3yLHEw@mail.gmail.com>

Il 04/07/2014 16:52, Ming Lei ha scritto:
>> > What you can do is change notify_guest to something like
>> >
>> >     qemu_bh_schedule(req->dev->dataplane->notify_guest_bh);
>> >
>> > and do the actual notification in the bottom half.  This should ensure that
>> > multiple notifications are coalesced, but it may also introduce new
>> > aio_notify calls even with my patch (a BH scheduled from a BH currently does
>> > an aio_notify; this can be fixed).
> I think we can do better than above because one aio IO completes lots of
> requests, and we just need to notify guest for all these requests.

Exactly, there would be just one BH and thus just one notify.

Paolo

  reply	other threads:[~2014-07-04 15:48 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-07-04 12:27 [Qemu-devel] [PATCH 0/2] virtio-blk: dataplane: one fix plus one optimization Ming Lei
2014-07-04 12:27 ` [Qemu-devel] [PATCH 1/2] virtio-blk: data-plane: fix save/set .complete_request in start Ming Lei
2014-07-04 12:27 ` [Qemu-devel] [PATCH 2/2] virtio-blk: dataplane: notify guest as a batch Ming Lei
2014-07-04 12:55   ` Paolo Bonzini
2014-07-04 14:52     ` Ming Lei
2014-07-04 15:48       ` Paolo Bonzini [this message]
2014-07-04 15:57         ` Ming Lei
2014-07-04 16:09           ` Paolo Bonzini
2014-07-05  4:21             ` Ming Lei

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