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virtio-blk: dataplane multiqueue support 

Monitor ioeventfds for all virtqueues in the device's AioContext.  This
is not true multiqueue because requests from all virtqueues are
processed in a single IOThread.  In the future it will be possible to
use multiple IOThreads when the QEMU block layer supports multiqueue.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 1466511196-12612-7-git-send-email-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2016-06-21 13:13:15 +01:00
parent 30d8bf6d17
commit 51b04ac5c6
1 changed files with 34 additions and 16 deletions
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50
hw/block/dataplane/virtio-blk.c
View File

@ -31,9 +31,7 @@ struct VirtIOBlockDataPlane {
bool stopping;
VirtIOBlkConf *conf;
VirtIODevice *vdev;
VirtQueue *vq; /* virtqueue vring */
QEMUBH *bh; /* bh for guest notification */
unsigned long *batch_notify_vqs;
@ -156,6 +154,8 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s->vdev)));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
VirtIOBlock *vblk = VIRTIO_BLK(s->vdev);
unsigned i;
unsigned nvqs = s->conf->num_queues;
int r;
if (vblk->dataplane_started || s->starting) {
@ -163,10 +163,9 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
}
s->starting = true;
s->vq = virtio_get_queue(s->vdev, 0);
/* Set up guest notifier (irq) */
r = k->set_guest_notifiers(qbus->parent, 1, true);
r = k->set_guest_notifiers(qbus->parent, nvqs, true);
if (r != 0) {
fprintf(stderr, "virtio-blk failed to set guest notifier (%d), "
"ensure -enable-kvm is set\n", r);
@ -174,10 +173,15 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
}
/* Set up virtqueue notify */
r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), 0, true);
if (r != 0) {
fprintf(stderr, "virtio-blk failed to set host notifier (%d)\n", r);
goto fail_host_notifier;
for (i = 0; i < nvqs; i++) {
r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, true);
if (r != 0) {
fprintf(stderr, "virtio-blk failed to set host notifier (%d)\n", r);
while (i--) {
virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
}
goto fail_guest_notifiers;
}
}
s->starting = false;
@ -187,17 +191,23 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
blk_set_aio_context(s->conf->conf.blk, s->ctx);
/* Kick right away to begin processing requests already in vring */
event_notifier_set(virtio_queue_get_host_notifier(s->vq));
for (i = 0; i < nvqs; i++) {
VirtQueue *vq = virtio_get_queue(s->vdev, i);
event_notifier_set(virtio_queue_get_host_notifier(vq));
}
/* Get this show started by hooking up our callbacks */
aio_context_acquire(s->ctx);
virtio_queue_aio_set_host_notifier_handler(s->vq, s->ctx,
virtio_blk_data_plane_handle_output);
for (i = 0; i < nvqs; i++) {
VirtQueue *vq = virtio_get_queue(s->vdev, i);
virtio_queue_aio_set_host_notifier_handler(vq, s->ctx,
virtio_blk_data_plane_handle_output);
}
aio_context_release(s->ctx);
return;
fail_host_notifier:
k->set_guest_notifiers(qbus->parent, 1, false);
fail_guest_notifiers:
vblk->dataplane_disabled = true;
s->starting = false;
@ -210,6 +220,8 @@ void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s->vdev)));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
VirtIOBlock *vblk = VIRTIO_BLK(s->vdev);
unsigned i;
unsigned nvqs = s->conf->num_queues;
if (!vblk->dataplane_started || s->stopping) {
return;
@ -227,17 +239,23 @@ void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
aio_context_acquire(s->ctx);
/* Stop notifications for new requests from guest */
virtio_queue_aio_set_host_notifier_handler(s->vq, s->ctx, NULL);
for (i = 0; i < nvqs; i++) {
VirtQueue *vq = virtio_get_queue(s->vdev, i);
virtio_queue_aio_set_host_notifier_handler(vq, s->ctx, NULL);
}
/* Drain and switch bs back to the QEMU main loop */
blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context());
aio_context_release(s->ctx);
virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), 0, false);
for (i = 0; i < nvqs; i++) {
virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
}
/* Clean up guest notifier (irq) */
k->set_guest_notifiers(qbus->parent, 1, false);
k->set_guest_notifiers(qbus->parent, nvqs, false);
vblk->dataplane_started = false;
s->stopping = false;