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[RFC 8/8] virtio-scsi: Use virtio_bus_set_host_notifiers()
From: |
Greg Kurz |
Subject: |
[RFC 8/8] virtio-scsi: Use virtio_bus_set_host_notifiers() |
Date: |
Thu, 25 Mar 2021 16:07:35 +0100 |
This allows the virtio-scsi-pci device to batch additions and deletions
of host notifiers. This significantly improves boot time of VMs with a
high number of vCPUs, e.g. from 6m13.969s down to 1m4.268s for a pseries
machine with 384 vCPUs.
Signed-off-by: Greg Kurz <groug@kaod.org>
---
hw/scsi/virtio-scsi-dataplane.c | 28 +++++++++++++---------------
1 file changed, 13 insertions(+), 15 deletions(-)
diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
index 11b53ab767be..eec2b6e19a5b 100644
--- a/hw/scsi/virtio-scsi-dataplane.c
+++ b/hw/scsi/virtio-scsi-dataplane.c
@@ -141,6 +141,7 @@ int virtio_scsi_dataplane_start(VirtIODevice *vdev)
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
VirtIOSCSI *s = VIRTIO_SCSI(vdev);
+ VirtioBusState *bus = VIRTIO_BUS(qbus);
if (s->dataplane_started ||
s->dataplane_starting ||
@@ -171,12 +172,9 @@ int virtio_scsi_dataplane_start(VirtIODevice *vdev)
vq_init_count++;
- for (i = 0; i < vs->conf.num_queues; i++) {
- rc = virtio_scsi_set_host_notifier(s, vs->cmd_vqs[i], i + 2);
- if (rc) {
- goto fail_host_notifiers;
- }
- vq_init_count++;
+ rc = virtio_bus_set_host_notifiers(bus, vs->conf.num_queues, 2, true);
+ if (rc) {
+ goto fail_host_notifiers;
}
aio_context_acquire(s->ctx);
@@ -196,10 +194,13 @@ int virtio_scsi_dataplane_start(VirtIODevice *vdev)
return 0;
fail_host_notifiers:
- for (i = 0; i < vq_init_count; i++) {
- virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
- virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
- }
+ /*
+ * Only host notifiers for ctrl_vq and event_vq can be set at
+ * this point. Notifiers for cmd_vqs[] have been reverted by
+ * virtio_bus_set_host_notifiers() already.
+ */
+ assert(vq_init_count <= 2);
+ virtio_bus_set_host_notifiers(bus, vq_init_count, 0, false);
k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
fail_guest_notifiers:
s->dataplane_fenced = true;
@@ -215,7 +216,6 @@ void virtio_scsi_dataplane_stop(VirtIODevice *vdev)
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
VirtIOSCSI *s = VIRTIO_SCSI(vdev);
- int i;
if (!s->dataplane_started || s->dataplane_stopping) {
return;
@@ -235,10 +235,8 @@ void virtio_scsi_dataplane_stop(VirtIODevice *vdev)
blk_drain_all(); /* ensure there are no in-flight requests */
- for (i = 0; i < vs->conf.num_queues + 2; i++) {
- virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
- virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
- }
+ virtio_bus_set_host_notifiers(VIRTIO_BUS(qbus), vs->conf.num_queues + 2, 0,
+ false);
/* Clean up guest notifier (irq) */
k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
--
2.26.3
- Re: [RFC 3/8] virtio: Add API to batch set host notifiers, (continued)
- [RFC 4/8] virtio-pci: Batch add/del ioeventfds in a single MR transaction, Greg Kurz, 2021/03/25
- [RFC 5/8] virtio-blk: Fix rollback path in virtio_blk_data_plane_start(), Greg Kurz, 2021/03/25
- [RFC 6/8] virtio-blk: Use virtio_bus_set_host_notifiers(), Greg Kurz, 2021/03/25
- [RFC 7/8] virtio-scsi: Set host notifiers and callbacks separately, Greg Kurz, 2021/03/25
- [RFC 8/8] virtio-scsi: Use virtio_bus_set_host_notifiers(),
Greg Kurz <=
- Re: [RFC 0/8] virtio: Improve boot time of virtio-scsi-pci and virtio-blk-pci, Michael S. Tsirkin, 2021/03/25
- Re: [RFC 0/8] virtio: Improve boot time of virtio-scsi-pci and virtio-blk-pci, Stefan Hajnoczi, 2021/03/29