Commit 5b2ffbe4d99843fd8305c573a100047a8c962327 ("virtio-blk: dataplane: notify guest as a batch") deferred guest notification to a BH in order batch notifications. This optimization is not specific to dataplane so move it to the generic virtio-blk code that is shared by both dataplane and non-dataplane code.
Note that this patch adds a flush function to force pending notifications. This way we can ensure notifications do not cross device reset or vmstate saving. Cc: Ming Lei <tom.leim...@gmail.com> Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com> --- hw/block/dataplane/virtio-blk.c | 10 ---------- hw/block/virtio-blk.c | 37 +++++++++++++++++++++++++++++++------ include/hw/virtio/virtio-blk.h | 1 + 3 files changed, 32 insertions(+), 16 deletions(-) diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c index 3cb97c9..e0ac4f4 100644 --- a/hw/block/dataplane/virtio-blk.c +++ b/hw/block/dataplane/virtio-blk.c @@ -35,7 +35,6 @@ struct VirtIOBlockDataPlane { VirtIODevice *vdev; VirtQueue *vq; /* virtqueue vring */ EventNotifier *guest_notifier; /* irq */ - QEMUBH *bh; /* bh for guest notification */ Notifier insert_notifier, remove_notifier; @@ -54,13 +53,6 @@ struct VirtIOBlockDataPlane { /* Raise an interrupt to signal guest, if necessary */ void virtio_blk_data_plane_notify(VirtIOBlockDataPlane *s) { - qemu_bh_schedule(s->bh); -} - -static void notify_guest_bh(void *opaque) -{ - VirtIOBlockDataPlane *s = opaque; - if (!virtio_should_notify(s->vdev, s->vq)) { return; } @@ -156,7 +148,6 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf, object_ref(OBJECT(s->iothread)); } s->ctx = iothread_get_aio_context(s->iothread); - s->bh = aio_bh_new(s->ctx, notify_guest_bh, s); s->insert_notifier.notify = data_plane_blk_insert_notifier; s->remove_notifier.notify = data_plane_blk_remove_notifier; @@ -179,7 +170,6 @@ void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s) data_plane_remove_op_blockers(s); notifier_remove(&s->insert_notifier); notifier_remove(&s->remove_notifier); - qemu_bh_delete(s->bh); object_unref(OBJECT(s->iothread)); g_free(s); } diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c index 284e646..0eaf6bf 100644 --- a/hw/block/virtio-blk.c +++ b/hw/block/virtio-blk.c @@ -45,20 +45,37 @@ void virtio_blk_free_request(VirtIOBlockReq *req) } } +/* Many requests can complete in an event loop iteration, we only notify the + * guest once. + */ +static void virtio_blk_batch_notify_bh(void *opaque) +{ + VirtIOBlock *s = opaque; + VirtIODevice *vdev = VIRTIO_DEVICE(s); + + if (s->dataplane_started && !s->dataplane_disabled) { + virtio_blk_data_plane_notify(s->dataplane); + } else { + virtio_notify(vdev, s->vq); + } +} + +/* Force batch notifications to run */ +static void virtio_blk_batch_notify_flush(VirtIOBlock *s) +{ + qemu_bh_cancel(s->batch_notify_bh); + virtio_blk_batch_notify_bh(s); +} + static void virtio_blk_req_complete(VirtIOBlockReq *req, unsigned char status) { VirtIOBlock *s = req->dev; - VirtIODevice *vdev = VIRTIO_DEVICE(s); trace_virtio_blk_req_complete(req, status); stb_p(&req->in->status, status); virtqueue_push(s->vq, &req->elem, req->in_len); - if (s->dataplane_started && !s->dataplane_disabled) { - virtio_blk_data_plane_notify(s->dataplane); - } else { - virtio_notify(vdev, s->vq); - } + qemu_bh_schedule(s->batch_notify_bh); } static int virtio_blk_handle_rw_error(VirtIOBlockReq *req, int error, @@ -664,6 +681,8 @@ static void virtio_blk_reset(VirtIODevice *vdev) if (s->dataplane) { virtio_blk_data_plane_stop(s->dataplane); } + + virtio_blk_batch_notify_flush(s); aio_context_release(ctx); blk_set_enable_write_cache(s->blk, s->original_wce); @@ -801,6 +820,8 @@ static void virtio_blk_save(QEMUFile *f, void *opaque) virtio_blk_data_plane_stop(s->dataplane); } + virtio_blk_batch_notify_flush(s); + virtio_save(vdev, f); } @@ -896,6 +917,9 @@ static void virtio_blk_device_realize(DeviceState *dev, Error **errp) return; } + s->batch_notify_bh = aio_bh_new(blk_get_aio_context(s->blk), + virtio_blk_batch_notify_bh, s); + s->change = qemu_add_vm_change_state_handler(virtio_blk_dma_restart_cb, s); register_savevm(dev, "virtio-blk", virtio_blk_id++, 2, virtio_blk_save, virtio_blk_load, s); @@ -910,6 +934,7 @@ static void virtio_blk_device_unrealize(DeviceState *dev, Error **errp) VirtIODevice *vdev = VIRTIO_DEVICE(dev); VirtIOBlock *s = VIRTIO_BLK(dev); + qemu_bh_delete(s->batch_notify_bh); virtio_blk_data_plane_destroy(s->dataplane); s->dataplane = NULL; qemu_del_vm_change_state_handler(s->change); diff --git a/include/hw/virtio/virtio-blk.h b/include/hw/virtio/virtio-blk.h index 8f2b056..b3834bc 100644 --- a/include/hw/virtio/virtio-blk.h +++ b/include/hw/virtio/virtio-blk.h @@ -49,6 +49,7 @@ typedef struct VirtIOBlock { VirtQueue *vq; void *rq; QEMUBH *bh; + QEMUBH *batch_notify_bh; VirtIOBlkConf conf; unsigned short sector_mask; bool original_wce; -- 2.5.5