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From: "Michael S. Tsirkin" <mst@redhat.com>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: virtualization@lists.linux-foundation.org,
	Anthony Liguori <anthony@codemonkey.ws>,
	qemu-devel@nongnu.org, kvm@vger.kernel.org
Subject: question on virtio
Date: Wed, 5 May 2010 14:09:47 +0300	[thread overview]
Message-ID: <20100505110947.GA27872@redhat.com> (raw)

Hi!
I see this in virtio_ring.c:

        /* Put entry in available array (but don't update avail->idx *
	   until they do sync). */

Why is it done this way?
It seems that updating the index straight away would be simpler, while
this might allow the host to specilatively look up the buffer and handle
it, without waiting for the kick.

-- 
MST

WARNING: multiple messages have this Message-ID (diff)
From: "Michael S. Tsirkin" <mst@redhat.com>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: kvm@vger.kernel.org, qemu-devel@nongnu.org,
	virtualization@lists.linux-foundation.org
Subject: [Qemu-devel] question on virtio
Date: Wed, 5 May 2010 14:09:47 +0300	[thread overview]
Message-ID: <20100505110947.GA27872@redhat.com> (raw)

Hi!
I see this in virtio_ring.c:

        /* Put entry in available array (but don't update avail->idx *
	   until they do sync). */

Why is it done this way?
It seems that updating the index straight away would be simpler, while
this might allow the host to specilatively look up the buffer and handle
it, without waiting for the kick.

-- 
MST

             reply	other threads:[~2010-05-05 11:13 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-05-05 11:09 Michael S. Tsirkin [this message]
2010-05-05 11:09 ` [Qemu-devel] question on virtio Michael S. Tsirkin
2010-05-05 19:40 ` Anthony Liguori
2010-05-05 19:40   ` [Qemu-devel] " Anthony Liguori
2010-05-05 20:59   ` Michael S. Tsirkin
2010-05-05 20:59   ` Michael S. Tsirkin
2010-05-05 20:59     ` [Qemu-devel] " Michael S. Tsirkin
2010-05-05 19:40 ` Anthony Liguori
2010-05-06  1:32 ` Rusty Russell
2010-05-06  1:32   ` [Qemu-devel] " Rusty Russell
2010-05-06  1:32 ` Rusty Russell
2010-05-06 16:43 ` [Qemu-devel] " Jamie Lokier
2010-05-06 16:43 ` Jamie Lokier
2010-05-06 16:43   ` Jamie Lokier
  -- strict thread matches above, loose matches on Subject: below --
2010-05-05 11:09 Michael S. Tsirkin

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