From: Raphael Norwitz <raphael.s.norwitz@gmail.com>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>,
Pankaj Gupta <pankaj.gupta.linux@gmail.com>,
Eduardo Habkost <ehabkost@redhat.com>,
qemu-block@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>,
cohuck@redhat.com, QEMU <qemu-devel@nongnu.org>,
Max Reitz <mreitz@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>, Fam Zheng <fam@euphon.net>,
Raphael Norwitz <raphael.norwitz@nutanix.com>
Subject: Re: [PATCH v4 5/5] vhost-user-blk: default num_queues to -smp N
Date: Sat, 30 May 2020 22:42:05 -0400 [thread overview]
Message-ID: <CAFubqFuCk42dRtKvC=V-A288y7JC398-fWSDPx7YsU97O8foGg@mail.gmail.com> (raw)
In-Reply-To: <20200527102925.128013-6-stefanha@redhat.com>
I'm happy with the code but as David pointed out with virtio-scsi, we
should probably add a comment about virtio_pci_optimal_num_queues()
capping the number of VQs here too.
On Wed, May 27, 2020 at 6:34 AM Stefan Hajnoczi <stefanha@redhat.com> 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.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> ---
> 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 9d8c0b3909..7a8639516f 100644
> --- a/hw/block/vhost-user-blk.c
> +++ b/hw/block/vhost-user-blk.c
> @@ -385,6 +385,9 @@ 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;
> @@ -496,7 +499,8 @@ 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 4aba3bdd3c..8cc4b54eec 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -32,6 +32,7 @@ GlobalProperty hw_compat_5_0[] = {
> { "virtio-blk-device", "num-queues", "1"},
> { "virtio-scsi-device", "num_queues", "1"},
> { "vhost-scsi", "num_queues", "1"},
> + { "vhost-user-blk", "num-queues", "1"},
> { "vhost-user-scsi", "num_queues", "1"},
> };
> const size_t hw_compat_5_0_len = G_N_ELEMENTS(hw_compat_5_0);
> diff --git a/hw/virtio/vhost-user-blk-pci.c b/hw/virtio/vhost-user-blk-pci.c
> index 58d7c31735..1c8ab7f5e6 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;
> }
> --
> 2.25.4
>
next prev parent reply other threads:[~2020-05-31 2:42 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-27 10:29 [PATCH v4 0/5] virtio-pci: enable blk and scsi multi-queue by default Stefan Hajnoczi
2020-05-27 10:29 ` [PATCH v4 1/5] virtio-pci: add virtio_pci_optimal_num_queues() helper Stefan Hajnoczi
2020-05-28 15:35 ` Cornelia Huck
2020-06-09 15:37 ` Michael S. Tsirkin
2020-07-06 13:25 ` Stefan Hajnoczi
2020-07-06 14:14 ` Cornelia Huck
2020-05-27 10:29 ` [PATCH v4 2/5] virtio-scsi: introduce a constant for fixed virtqueues Stefan Hajnoczi
2020-05-28 14:18 ` Pankaj Gupta
2020-05-28 15:22 ` Philippe Mathieu-Daudé
2020-05-31 2:43 ` Raphael Norwitz
2020-05-27 10:29 ` [PATCH v4 3/5] virtio-scsi: default num_queues to -smp N Stefan Hajnoczi
2020-05-27 10:38 ` Daniel P. Berrangé
2020-05-28 8:50 ` Stefan Hajnoczi
2020-05-27 10:29 ` [PATCH v4 4/5] virtio-blk: " Stefan Hajnoczi
2020-05-28 14:45 ` Pankaj Gupta
2020-05-27 10:29 ` [PATCH v4 5/5] vhost-user-blk: " Stefan Hajnoczi
2020-05-31 2:42 ` Raphael Norwitz [this message]
2020-06-09 15:36 ` Michael S. Tsirkin
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