On Thu, Sep 27, 2012 at 12:01 PM, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
> 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?
I've played with disable_cb/enable_cb previously in virtio-blk and
virtio-scsi when aliguori had suggested reducing notifies. I
definitely didn't invent it :).
Stefan
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