From 9ef9d40261cc05c01545f46b49dddfe39602e1c8 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Thu, 1 Dec 2016 19:26:46 +0000 Subject: [PATCH] virtio-blk: suppress virtqueue kick during processing 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 Reviewed-by: Paolo Bonzini Message-id: 20161201192652.9509-8-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi --- hw/block/virtio-blk.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c index 0c5fd27593..50bb0cbb93 100644 --- a/hw/block/virtio-blk.c +++ b/hw/block/virtio-blk.c @@ -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); -- 2.39.2