From: Gal Hammer <gham...@redhat.com> The loading time of a VM is quite significant when its virtio devices use a large amount of virt-queues (e.g. a virtio-serial device with max_ports=511). Most of the time is spend in the creation of all the required event notifiers (ioeventfd and memory regions).
This patch pack all the changes to the memory regions in a single memory transaction. Reported-by: Sitong Liu Reported-by: Xiaoling Gao Signed-off-by: Gal Hammer <gham...@redhat.com> Reviewed-by: Michael S. Tsirkin <m...@redhat.com> Signed-off-by: Michael S. Tsirkin <m...@redhat.com> Reviewed-by: Greg Kurz <gr...@kaod.org> Tested-by: Greg Kurz <gr...@kaod.org> --- hw/virtio/virtio.c | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 3667cd6..006d3d1 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -2572,8 +2572,9 @@ static Property virtio_properties[] = { static int virtio_device_start_ioeventfd_impl(VirtIODevice *vdev) { VirtioBusState *qbus = VIRTIO_BUS(qdev_get_parent_bus(DEVICE(vdev))); - int n, r, err; + int i, n, r, err; + memory_region_transaction_begin(); for (n = 0; n < VIRTIO_QUEUE_MAX; n++) { VirtQueue *vq = &vdev->vq[n]; if (!virtio_queue_get_num(vdev, n)) { @@ -2596,9 +2597,11 @@ static int virtio_device_start_ioeventfd_impl(VirtIODevice *vdev) } event_notifier_set(&vq->host_notifier); } + memory_region_transaction_commit(); return 0; assign_error: + i = n; /* save n for a second iteration after transaction is committed. */ while (--n >= 0) { VirtQueue *vq = &vdev->vq[n]; if (!virtio_queue_get_num(vdev, n)) { @@ -2608,7 +2611,14 @@ assign_error: event_notifier_set_handler(&vq->host_notifier, NULL); r = virtio_bus_set_host_notifier(qbus, n, false); assert(r >= 0); - virtio_bus_cleanup_host_notifier(qbus, n); + } + memory_region_transaction_commit(); + + while (--i >= 0) { + if (!virtio_queue_get_num(vdev, i)) { + continue; + } + virtio_bus_cleanup_host_notifier(qbus, i); } return err; } @@ -2626,6 +2636,7 @@ static void virtio_device_stop_ioeventfd_impl(VirtIODevice *vdev) VirtioBusState *qbus = VIRTIO_BUS(qdev_get_parent_bus(DEVICE(vdev))); int n, r; + memory_region_transaction_begin(); for (n = 0; n < VIRTIO_QUEUE_MAX; n++) { VirtQueue *vq = &vdev->vq[n]; @@ -2635,6 +2646,13 @@ static void virtio_device_stop_ioeventfd_impl(VirtIODevice *vdev) event_notifier_set_handler(&vq->host_notifier, NULL); r = virtio_bus_set_host_notifier(qbus, n, false); assert(r >= 0); + } + memory_region_transaction_commit(); + + for (n = 0; n < VIRTIO_QUEUE_MAX; n++) { + if (!virtio_queue_get_num(vdev, n)) { + continue; + } virtio_bus_cleanup_host_notifier(qbus, n); } } -- MST