Il 27/09/2012 02:10, Rusty Russell ha scritto:

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+	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