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[Qemu-devel] [PULL 09/14] virtio-scsi: suppress virtqueue kick during pr
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PULL 09/14] virtio-scsi: suppress virtqueue kick during processing |
Date: |
Wed, 4 Jan 2017 13:34:09 +0000 |
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 <address@hidden>
Reviewed-by: Paolo Bonzini <address@hidden>
Message-id: address@hidden
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
hw/scsi/virtio-scsi.c | 36 +++++++++++++++++++++---------------
1 file changed, 21 insertions(+), 15 deletions(-)
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 34bba35..204e14f 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);
--
2.9.3
- [Qemu-devel] [PULL 00/14] Block patches, Stefan Hajnoczi, 2017/01/04
- [Qemu-devel] [PULL 02/14] aio: add flag to skip fds to aio_dispatch(), Stefan Hajnoczi, 2017/01/04
- [Qemu-devel] [PULL 01/14] HACKING: document #include order, Stefan Hajnoczi, 2017/01/04
- [Qemu-devel] [PULL 04/14] aio: add polling mode to AioContext, Stefan Hajnoczi, 2017/01/04
- [Qemu-devel] [PULL 06/14] linux-aio: poll ring for completions, Stefan Hajnoczi, 2017/01/04
- [Qemu-devel] [PULL 07/14] iothread: add polling parameters, Stefan Hajnoczi, 2017/01/04
- [Qemu-devel] [PULL 05/14] virtio: poll virtqueues for new buffers, Stefan Hajnoczi, 2017/01/04
- [Qemu-devel] [PULL 03/14] aio: add AioPollFn and io_poll() interface, Stefan Hajnoczi, 2017/01/04
- [Qemu-devel] [PULL 08/14] virtio-blk: suppress virtqueue kick during processing, Stefan Hajnoczi, 2017/01/04
- [Qemu-devel] [PULL 09/14] virtio-scsi: suppress virtqueue kick during processing,
Stefan Hajnoczi <=
- [Qemu-devel] [PULL 10/14] virtio: turn vq->notification into a nested counter, Stefan Hajnoczi, 2017/01/04
- [Qemu-devel] [PULL 12/14] virtio: disable virtqueue notifications during polling, Stefan Hajnoczi, 2017/01/04
- [Qemu-devel] [PULL 11/14] aio: add .io_poll_begin/end() callbacks, Stefan Hajnoczi, 2017/01/04
- [Qemu-devel] [PULL 13/14] aio: self-tune polling time, Stefan Hajnoczi, 2017/01/04
- [Qemu-devel] [PULL 14/14] iothread: add poll-grow and poll-shrink parameters, Stefan Hajnoczi, 2017/01/04
- Re: [Qemu-devel] [PULL 00/14] Block patches, Peter Maydell, 2017/01/05