On Mon, Jul 6, 2020 at 7:00 AM Stefan Hajnoczi wrote:
>
> 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
> Reviewed-by: Cornelia Huck
> ---
> include/hw/virtio/vhost-user-blk.h | 2 ++
> hw/block/vhost-user-blk.c | 6 +-
> hw/core/machine.c | 1 +
> hw/virtio/vhost-user-blk-pci.c | 4
> 4 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/include/hw/virtio/vhost-user-blk.h
> b/include/hw/virtio/vhost-user-blk.h
> index 34ad6f0c0e..292d17147c 100644
> --- 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;
> diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
> index a00b854736..39aec42dae 100644
> --- 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;
> +}
What is this check for? Is it just a backstop to ensure that
num_queues is set to 1 if vhost-user-blk-pci doesn't update it?
> 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 845f6476cb..31bfaacdb5 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -30,6 +30,7 @@
>
> GlobalProperty hw_compat_5_0[] = {
> { "vhost-scsi", "num_queues", "1"},
> +{ "vhost-user-blk", "num-queues", "1"},
> { "vhost-user-scsi", "num_queues", "1"},
> { "virtio-balloon-device", "page-poison", "false" },
> { "virtio-blk-device", "num-queues", "1"},
> diff --git a/hw/virtio/vhost-user-blk-pci.c b/hw/virtio/vhost-user-blk-pci.c
> index 4f5d5cbf44..a62a71e067 100644
> --- 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;
> }
> --
> 2.26.2
>
