From mboxrd@z Thu Jan  1 00:00:00 1970
From: Anthony Liguori <anthony@codemonkey.ws>
Subject: Re: question on virtio
Date: Wed, 05 May 2010 14:40:15 -0500
Message-ID: <4BE1C99F.6050205@codemonkey.ws>
References: <20100505110947.GA27872@redhat.com>
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Cc: Rusty Russell <rusty@rustcorp.com.au>,
	virtualization@lists.linux-foundation.org, qemu-devel@nongnu.org,
	kvm@vger.kernel.org
To: "Michael S. Tsirkin" <mst@redhat.com>
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On 05/05/2010 06:09 AM, Michael S. Tsirkin wrote:
> 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.
>    

It should be okay as long as you don't update idx for partial vectors.

Regards,

Anthony Liguori