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authorStefan Hajnoczi <stefanha@redhat.com>2016-12-01 19:26:47 +0000
committerStefan Hajnoczi <stefanha@redhat.com>2017-01-03 16:38:49 +0000
commit23425cc2b7a9de7ade132399ca146b882ac4d72b (patch)
treeec6ad75e0102970bdf765969988e9ed497f232a2 /hw/scsi
parent9ef9d40261cc05c01545f46b49dddfe39602e1c8 (diff)
virtio-scsi: 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 <stefanha@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Message-id: 20161201192652.9509-9-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'hw/scsi')
-rw-r--r--hw/scsi/virtio-scsi.c36
1 files changed, 21 insertions, 15 deletions
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 34bba35d83..204e14f237 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -592,26 +592,32 @@ static void virtio_scsi_handle_cmd_req_submit(VirtIOSCSI *s, VirtIOSCSIReq *req)
void virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq)
{
VirtIOSCSIReq *req, *next;
- int ret;
+ int ret = 0;
QTAILQ_HEAD(, VirtIOSCSIReq) reqs = QTAILQ_HEAD_INITIALIZER(reqs);
- while ((req = virtio_scsi_pop_req(s, vq))) {
- ret = virtio_scsi_handle_cmd_req_prepare(s, req);
- if (!ret) {
- QTAILQ_INSERT_TAIL(&reqs, req, next);
- } else if (ret == -EINVAL) {
- /* The device is broken and shouldn't process any request */
- while (!QTAILQ_EMPTY(&reqs)) {
- req = QTAILQ_FIRST(&reqs);
- QTAILQ_REMOVE(&reqs, req, next);
- blk_io_unplug(req->sreq->dev->conf.blk);
- scsi_req_unref(req->sreq);
- virtqueue_detach_element(req->vq, &req->elem, 0);
- virtio_scsi_free_req(req);
+ do {
+ virtio_queue_set_notification(vq, 0);
+
+ while ((req = virtio_scsi_pop_req(s, vq))) {
+ ret = virtio_scsi_handle_cmd_req_prepare(s, req);
+ if (!ret) {
+ QTAILQ_INSERT_TAIL(&reqs, req, next);
+ } else if (ret == -EINVAL) {
+ /* The device is broken and shouldn't process any request */
+ while (!QTAILQ_EMPTY(&reqs)) {
+ req = QTAILQ_FIRST(&reqs);
+ QTAILQ_REMOVE(&reqs, req, next);
+ blk_io_unplug(req->sreq->dev->conf.blk);
+ scsi_req_unref(req->sreq);
+ virtqueue_detach_element(req->vq, &req->elem, 0);
+ virtio_scsi_free_req(req);
+ }
}
}
- }
+
+ virtio_queue_set_notification(vq, 1);
+ } while (ret != -EINVAL && !virtio_queue_empty(vq));
QTAILQ_FOREACH_SAFE(req, &reqs, next, next) {
virtio_scsi_handle_cmd_req_submit(s, req);