From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH] virtio-blk: Disable callback in virtblk_done()
Date: Thu, 27 Sep 2012 12:01:36 +0200
Message-ID: <50642400.5030906@redhat.com>
References: <1348540577-7474-1-git-send-email-asias@redhat.com> <5061BAED.9020205@redhat.com> <87ehlo497o.fsf@rustcorp.com.au>
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Cc: Asias He <asias@redhat.com>,
	virtualization@lists.linux-foundation.org, kvm@vger.kernel.org,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Stefan Hajnoczi <stefanha@gmail.com>
To: Rusty Russell <rusty@rustcorp.com.au>
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Il 27/09/2012 02:10, Rusty Russell ha scritto:
>>> >> +	do {
>>> >> +		virtqueue_disable_cb(vq);
>>> >> +		while ((vbr = virtqueue_get_buf(vblk->vq, &len)) != NULL) {
>>> >> +			if (vbr->bio) {
>>> >> +				virtblk_bio_done(vbr);
>>> >> +				bio_done = true;
>>> >> +			} else {
>>> >> +				virtblk_request_done(vbr);
>>> >> +				req_done = true;
>>> >> +			}
>>> >>  		}
>>> >> -	}
>>> >> +	} while (!virtqueue_enable_cb(vq));
>>> >>  	/* In case queue is stopped waiting for more buffers. */
>>> >>  	if (req_done)
>>> >>  		blk_start_queue(vblk->disk->queue);
> Fascinating.  Please just confirm that VIRTIO_RING_F_EVENT_IDX is
> enabled?

Yeah, it's a nice and cheap trick.  Stefan, I see that you had this in
virtio-scsi since even before I picked it up.  Do you remember how you
came up with it?

Paolo