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virtio-scsi-pci: default num_queues to -smp N

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Automatically size the number of virtio-scsi-pci, vhost-scsi-pci, and
vhost-user-scsi-pci request virtqueues to match the number of vCPUs.
Other transports continue to default to 1 request virtqueue.

A 1:1 virtqueue:vCPU mapping ensures that completion interrupts are
handled on the same vCPU that submitted the request.  No IPI is
necessary to complete an I/O request and performance is improved.  The
maximum number of MSI-X vectors and virtqueues limit are respected.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20200818143348.310613-6-stefanha@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2020-08-18 15:33:46 +01:00 • committed by Michael S. Tsirkin
parent 4e5163bd84
commit 6a55882284
8 changed files with 37 additions and 13 deletions
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6
hw/scsi/virtio-scsi.c
View file

@ -891,6 +891,9 @@ void virtio_scsi_common_realize(DeviceState *dev,
virtio_init(vdev, "virtio-scsi", VIRTIO_ID_SCSI,
sizeof(VirtIOSCSIConfig));
if (s->conf.num_queues == VIRTIO_SCSI_AUTO_NUM_QUEUES) {
s->conf.num_queues = 1;
}
if (s->conf.num_queues == 0 ||
s->conf.num_queues > VIRTIO_QUEUE_MAX - VIRTIO_SCSI_VQ_NUM_FIXED) {
error_setg(errp, "Invalid number of queues (= %" PRIu32 "), "
@ -964,7 +967,8 @@ static void virtio_scsi_device_unrealize(DeviceState *dev)
}
static Property virtio_scsi_properties[] = {
DEFINE_PROP_UINT32("num_queues", VirtIOSCSI, parent_obj.conf.num_queues, 1),
DEFINE_PROP_UINT32("num_queues", VirtIOSCSI, parent_obj.conf.num_queues,
VIRTIO_SCSI_AUTO_NUM_QUEUES),
DEFINE_PROP_UINT32("virtqueue_size", VirtIOSCSI,
parent_obj.conf.virtqueue_size, 256),
DEFINE_PROP_BOOL("seg_max_adjust", VirtIOSCSI,