[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PATCH v3 2/2] virtio: improve virtio devices initializatio
From: |
Gal Hammer |
Subject: |
[Qemu-devel] [PATCH v3 2/2] virtio: improve virtio devices initialization time |
Date: |
Mon, 29 Jan 2018 16:20:57 +0200 |
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 <address@hidden>
Reported-by: Xiaoling Gao <address@hidden>
Signed-off-by: Gal Hammer <address@hidden>
---
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);
}
}
--
2.7.5