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[Qemu-devel] [PATCH] virtio: improve virtio devices initialization time
From: |
Gal Hammer |
Subject: |
[Qemu-devel] [PATCH] virtio: improve virtio devices initialization time |
Date: |
Thu, 11 Jan 2018 12:16:56 +0200 |
The loading time of a VM is quite significant when its virtio
devices uses 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 | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index ad564b0..8d8d93d 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -2574,6 +2574,7 @@ static int
virtio_device_start_ioeventfd_impl(VirtIODevice *vdev)
VirtioBusState *qbus = VIRTIO_BUS(qdev_get_parent_bus(DEVICE(vdev)));
int 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)) {
@@ -2596,6 +2597,7 @@ static int
virtio_device_start_ioeventfd_impl(VirtIODevice *vdev)
}
event_notifier_set(&vq->host_notifier);
}
+ memory_region_transaction_commit();
return 0;
assign_error:
@@ -2609,6 +2611,7 @@ assign_error:
r = virtio_bus_set_host_notifier(qbus, n, false);
assert(r >= 0);
}
+ memory_region_transaction_commit();
return err;
}
@@ -2625,6 +2628,7 @@ 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];
@@ -2632,6 +2636,13 @@ static void
virtio_device_stop_ioeventfd_impl(VirtIODevice *vdev)
continue;
}
event_notifier_set_handler(&vq->host_notifier, NULL);
+ }
+ memory_region_transaction_commit();
+
+ for (n = 0; n < VIRTIO_QUEUE_MAX; n++) {
+ if (!virtio_queue_get_num(vdev, n)) {
+ continue;
+ }
r = virtio_bus_set_host_notifier(qbus, n, false);
assert(r >= 0);
}
--
2.7.5
- [Qemu-devel] [PATCH] virtio: improve virtio devices initialization time,
Gal Hammer <=