vhost-user-blk-pci: default num_queues to -smp N

Automatically size the number of request virtqueues to match the number
of vCPUs.  This 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>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Message-Id: <20200818143348.310613-8-stefanha@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
index a00b85473648b8e8700ec5b482e3d21543ee505f..39aec42dae9052a420aec8e64f34ecc2e346671e 100644 (file)
--- a/hw/block/vhost-user-blk.c
+++ b/hw/block/vhost-user-blk.c
@@ -420,6 +420,9 @@ static void vhost_user_blk_device_realize(DeviceState *dev, Error **errp)
         return;
     }
 
+    if (s->num_queues == VHOST_USER_BLK_AUTO_NUM_QUEUES) {
+        s->num_queues = 1;
+    }
     if (!s->num_queues || s->num_queues > VIRTIO_QUEUE_MAX) {
         error_setg(errp, "vhost-user-blk: invalid number of IO queues");
         return;
@@ -531,7 +534,8 @@ static const VMStateDescription vmstate_vhost_user_blk = {
 
 static Property vhost_user_blk_properties[] = {
     DEFINE_PROP_CHR("chardev", VHostUserBlk, chardev),
-    DEFINE_PROP_UINT16("num-queues", VHostUserBlk, num_queues, 1),
+    DEFINE_PROP_UINT16("num-queues", VHostUserBlk, num_queues,
+                       VHOST_USER_BLK_AUTO_NUM_QUEUES),
     DEFINE_PROP_UINT32("queue-size", VHostUserBlk, queue_size, 128),
     DEFINE_PROP_BIT("config-wce", VHostUserBlk, config_wce, 0, true),
     DEFINE_PROP_END_OF_LIST(),

diff --git a/hw/core/machine.c b/hw/core/machine.c
index 7f65fa8743610983686f2502327642ee32f9c0be..ea26d612374de592d4c3d82d2050a78e3d05a28e 100644 (file)
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -30,6 +30,7 @@
 
 GlobalProperty hw_compat_5_1[] = {
     { "vhost-scsi", "num_queues", "1"},
+    { "vhost-user-blk", "num-queues", "1"},
     { "vhost-user-scsi", "num_queues", "1"},
     { "virtio-blk-device", "num-queues", "1"},
     { "virtio-scsi-device", "num_queues", "1"},

diff --git a/hw/virtio/vhost-user-blk-pci.c b/hw/virtio/vhost-user-blk-pci.c
index 4f5d5cbf44a8da7b50831701d434c8ca459fedbb..a62a71e067b478f5ed987f2d779e4eae4386b443 100644 (file)
--- a/hw/virtio/vhost-user-blk-pci.c
+++ b/hw/virtio/vhost-user-blk-pci.c
@@ -54,6 +54,10 @@ static void vhost_user_blk_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
     VHostUserBlkPCI *dev = VHOST_USER_BLK_PCI(vpci_dev);
     DeviceState *vdev = DEVICE(&dev->vdev);
 
+    if (dev->vdev.num_queues == VHOST_USER_BLK_AUTO_NUM_QUEUES) {
+        dev->vdev.num_queues = virtio_pci_optimal_num_queues(0);
+    }
+
     if (vpci_dev->nvectors == DEV_NVECTORS_UNSPECIFIED) {
         vpci_dev->nvectors = dev->vdev.num_queues + 1;
     }

diff --git a/include/hw/virtio/vhost-user-blk.h b/include/hw/virtio/vhost-user-blk.h
index 34ad6f0c0e2d967dec2dde3ebac5b99b6f89b71b..292d17147c62a8bc0a01f39e0a58a6593fc8be97 100644 (file)
--- a/include/hw/virtio/vhost-user-blk.h
+++ b/include/hw/virtio/vhost-user-blk.h
@@ -25,6 +25,8 @@
 #define VHOST_USER_BLK(obj) \
         OBJECT_CHECK(VHostUserBlk, (obj), TYPE_VHOST_USER_BLK)
 
+#define VHOST_USER_BLK_AUTO_NUM_QUEUES UINT16_MAX
+
 typedef struct VHostUserBlk {
     VirtIODevice parent_obj;
     CharBackend chardev;