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virtio-blk: suppress virtqueue kick during processing

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The guest does not need to kick the virtqueue while we are processing
it.  This reduces the number of vmexits during periods of heavy I/O.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20161201192652.9509-8-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2016-12-01 19:26:46 +00:00
parent 0d9d86fb4d
commit 9ef9d40261
1 changed files with 12 additions and 6 deletions
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18
hw/block/virtio-blk.c
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@ -588,13 +588,19 @@ void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq)
blk_io_plug(s->blk);
while ((req = virtio_blk_get_request(s, vq))) {
if (virtio_blk_handle_request(req, &mrb)) {
virtqueue_detach_element(req->vq, &req->elem, 0);
virtio_blk_free_request(req);
break;
do {
virtio_queue_set_notification(vq, 0);
while ((req = virtio_blk_get_request(s, vq))) {
if (virtio_blk_handle_request(req, &mrb)) {
virtqueue_detach_element(req->vq, &req->elem, 0);
virtio_blk_free_request(req);
break;
}
}
}
virtio_queue_set_notification(vq, 1);
} while (!virtio_queue_empty(vq));
if (mrb.num_reqs) {
virtio_blk_submit_multireq(s->blk, &mrb);