From c4f5dcc4360a02085a633fd7a90b7ac395ca1ba4 Mon Sep 17 00:00:00 2001 From: Greg Kurz Date: Wed, 7 Apr 2021 16:35:01 +0200 Subject: [PATCH] virtio-scsi: Configure all host notifiers in a single MR transaction This allows the virtio-scsi-pci device to batch the setup of all its host notifiers. This significantly improves boot time of VMs with a high number of vCPUs, e.g. from 6m5.563s down to 1m2.884s for a pseries machine with 384 vCPUs. Note that memory_region_transaction_commit() must be called before virtio_bus_cleanup_host_notifier() because the latter might close ioeventfds that the transaction still assumes to be around when it commits. Signed-off-by: Greg Kurz Message-Id: <20210407143501.244343-5-groug@kaod.org> Reviewed-by: Stefan Hajnoczi Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/scsi/virtio-scsi-dataplane.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c index b2cb3d9dcc..28e003250a 100644 --- a/hw/scsi/virtio-scsi-dataplane.c +++ b/hw/scsi/virtio-scsi-dataplane.c @@ -152,6 +152,8 @@ int virtio_scsi_dataplane_start(VirtIODevice *vdev) goto fail_guest_notifiers; } + memory_region_transaction_begin(); + rc = virtio_scsi_set_host_notifier(s, vs->ctrl_vq, 0); if (rc != 0) { goto fail_host_notifiers; @@ -173,6 +175,8 @@ int virtio_scsi_dataplane_start(VirtIODevice *vdev) vq_init_count++; } + memory_region_transaction_commit(); + aio_context_acquire(s->ctx); virtio_queue_aio_set_host_notifier_handler(vs->ctrl_vq, s->ctx, virtio_scsi_data_plane_handle_ctrl); @@ -192,6 +196,11 @@ int virtio_scsi_dataplane_start(VirtIODevice *vdev) fail_host_notifiers: for (i = 0; i < vq_init_count; i++) { virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false); + } + + memory_region_transaction_commit(); + + for (i = 0; i < vq_init_count; i++) { virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i); } k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false); @@ -229,8 +238,15 @@ void virtio_scsi_dataplane_stop(VirtIODevice *vdev) blk_drain_all(); /* ensure there are no in-flight requests */ + memory_region_transaction_begin(); + for (i = 0; i < vs->conf.num_queues + 2; i++) { virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false); + } + + memory_region_transaction_commit(); + + for (i = 0; i < vs->conf.num_queues + 2; i++) { virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i); }