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Re: [Qemu-devel] [PATCH V3] tap: vhost busy polling support
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From: |
Greg Kurz |
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Subject: |
Re: [Qemu-devel] [PATCH V3] tap: vhost busy polling support |
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Date: |
Thu, 7 Apr 2016 18:07:44 +0200 |
On Thu, 7 Apr 2016 12:56:24 +0800
Jason Wang <address@hidden> wrote:
> This patch add the capability of basic vhost net busy polling which is
> supported by recent kernel. User could configure the maximum number of
> us that could be spent on busy polling through a new property of tap
> "vhost-poll-us".
>
> Signed-off-by: Jason Wang <address@hidden>
> ---
Thanks for this feature Jason !
Tested-by: Greg Kurz <address@hidden>
> hw/net/vhost_net.c | 2 +-
> hw/scsi/vhost-scsi.c | 2 +-
> hw/virtio/vhost-backend.c | 8 ++++++++
> hw/virtio/vhost.c | 40
> ++++++++++++++++++++++++++++++++++++++-
> include/hw/virtio/vhost-backend.h | 3 +++
> include/hw/virtio/vhost.h | 3 ++-
> include/net/vhost_net.h | 1 +
> net/tap.c | 10 ++++++++--
> net/vhost-user.c | 1 +
> qapi-schema.json | 6 +++++-
> qemu-options.hx | 3 +++
> 11 files changed, 72 insertions(+), 7 deletions(-)
>
> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> index 6e1032f..1840c73 100644
> --- a/hw/net/vhost_net.c
> +++ b/hw/net/vhost_net.c
> @@ -166,7 +166,7 @@ struct vhost_net *vhost_net_init(VhostNetOptions *options)
> }
>
> r = vhost_dev_init(&net->dev, options->opaque,
> - options->backend_type);
> + options->backend_type, options->busyloop_timeout);
> if (r < 0) {
> goto fail;
> }
> diff --git a/hw/scsi/vhost-scsi.c b/hw/scsi/vhost-scsi.c
> index 9261d51..2a00f2f 100644
> --- a/hw/scsi/vhost-scsi.c
> +++ b/hw/scsi/vhost-scsi.c
> @@ -248,7 +248,7 @@ static void vhost_scsi_realize(DeviceState *dev, Error
> **errp)
> s->dev.backend_features = 0;
>
> ret = vhost_dev_init(&s->dev, (void *)(uintptr_t)vhostfd,
> - VHOST_BACKEND_TYPE_KERNEL);
> + VHOST_BACKEND_TYPE_KERNEL, 0);
> if (ret < 0) {
> error_setg(errp, "vhost-scsi: vhost initialization failed: %s",
> strerror(-ret));
> diff --git a/hw/virtio/vhost-backend.c b/hw/virtio/vhost-backend.c
> index b358902..d62372e 100644
> --- a/hw/virtio/vhost-backend.c
> +++ b/hw/virtio/vhost-backend.c
> @@ -138,6 +138,12 @@ static int vhost_kernel_set_vring_call(struct vhost_dev
> *dev,
> return vhost_kernel_call(dev, VHOST_SET_VRING_CALL, file);
> }
>
> +static int vhost_kernel_set_vring_busyloop_timeout(struct vhost_dev *dev,
> + struct vhost_vring_state
> *s)
> +{
> + return vhost_kernel_call(dev, VHOST_SET_VRING_BUSYLOOP_TIMEOUT, s);
> +}
> +
> static int vhost_kernel_set_features(struct vhost_dev *dev,
> uint64_t features)
> {
> @@ -185,6 +191,8 @@ static const VhostOps kernel_ops = {
> .vhost_get_vring_base = vhost_kernel_get_vring_base,
> .vhost_set_vring_kick = vhost_kernel_set_vring_kick,
> .vhost_set_vring_call = vhost_kernel_set_vring_call,
> + .vhost_set_vring_busyloop_timeout =
> + vhost_kernel_set_vring_busyloop_timeout,
> .vhost_set_features = vhost_kernel_set_features,
> .vhost_get_features = vhost_kernel_get_features,
> .vhost_set_owner = vhost_kernel_set_owner,
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index 4400718..ebf8b08 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -964,6 +964,28 @@ static void vhost_eventfd_del(MemoryListener *listener,
> {
> }
>
> +static int vhost_virtqueue_set_busyloop_timeout(struct vhost_dev *dev,
> + int n, uint32_t timeout)
> +{
> + int vhost_vq_index = dev->vhost_ops->vhost_get_vq_index(dev, n);
> + struct vhost_vring_state state = {
> + .index = vhost_vq_index,
> + .num = timeout,
> + };
> + int r;
> +
> + if (!dev->vhost_ops->vhost_set_vring_busyloop_timeout) {
> + return -EINVAL;
> + }
> +
> + r = dev->vhost_ops->vhost_set_vring_busyloop_timeout(dev, &state);
> + if (r) {
> + return r;
> + }
> +
> + return 0;
> +}
> +
> static int vhost_virtqueue_init(struct vhost_dev *dev,
> struct vhost_virtqueue *vq, int n)
> {
> @@ -994,7 +1016,7 @@ static void vhost_virtqueue_cleanup(struct
> vhost_virtqueue *vq)
> }
>
> int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
> - VhostBackendType backend_type)
> + VhostBackendType backend_type, uint32_t busyloop_timeout)
> {
> uint64_t features;
> int i, r;
> @@ -1035,6 +1057,17 @@ int vhost_dev_init(struct vhost_dev *hdev, void
> *opaque,
> goto fail_vq;
> }
> }
> +
> + if (busyloop_timeout) {
> + for (i = 0; i < hdev->nvqs; ++i) {
> + r = vhost_virtqueue_set_busyloop_timeout(hdev, hdev->vq_index +
> i,
> + busyloop_timeout);
> + if (r < 0) {
> + goto fail_busyloop;
> + }
> + }
> + }
> +
> hdev->features = features;
>
> hdev->memory_listener = (MemoryListener) {
> @@ -1077,6 +1110,11 @@ int vhost_dev_init(struct vhost_dev *hdev, void
> *opaque,
> hdev->memory_changed = false;
> memory_listener_register(&hdev->memory_listener, &address_space_memory);
> return 0;
> +fail_busyloop:
> + while (--i >= 0) {
> + vhost_virtqueue_set_busyloop_timeout(hdev, hdev->vq_index + i, 0);
> + }
> + i = hdev->nvqs;
> fail_vq:
> while (--i >= 0) {
> vhost_virtqueue_cleanup(hdev->vqs + i);
> diff --git a/include/hw/virtio/vhost-backend.h
> b/include/hw/virtio/vhost-backend.h
> index 95fcc96..84e1cb7 100644
> --- a/include/hw/virtio/vhost-backend.h
> +++ b/include/hw/virtio/vhost-backend.h
> @@ -57,6 +57,8 @@ typedef int (*vhost_set_vring_kick_op)(struct vhost_dev
> *dev,
> struct vhost_vring_file *file);
> typedef int (*vhost_set_vring_call_op)(struct vhost_dev *dev,
> struct vhost_vring_file *file);
> +typedef int (*vhost_set_vring_busyloop_timeout_op)(struct vhost_dev *dev,
> + struct vhost_vring_state
> *r);
> typedef int (*vhost_set_features_op)(struct vhost_dev *dev,
> uint64_t features);
> typedef int (*vhost_get_features_op)(struct vhost_dev *dev,
> @@ -91,6 +93,7 @@ typedef struct VhostOps {
> vhost_get_vring_base_op vhost_get_vring_base;
> vhost_set_vring_kick_op vhost_set_vring_kick;
> vhost_set_vring_call_op vhost_set_vring_call;
> + vhost_set_vring_busyloop_timeout_op vhost_set_vring_busyloop_timeout;
> vhost_set_features_op vhost_set_features;
> vhost_get_features_op vhost_get_features;
> vhost_set_owner_op vhost_set_owner;
> diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
> index b60d758..2106ed8 100644
> --- a/include/hw/virtio/vhost.h
> +++ b/include/hw/virtio/vhost.h
> @@ -64,7 +64,8 @@ struct vhost_dev {
> };
>
> int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
> - VhostBackendType backend_type);
> + VhostBackendType backend_type,
> + uint32_t busyloop_timeout);
> void vhost_dev_cleanup(struct vhost_dev *hdev);
> int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev);
> void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev);
> diff --git a/include/net/vhost_net.h b/include/net/vhost_net.h
> index 3389b41..8354b98 100644
> --- a/include/net/vhost_net.h
> +++ b/include/net/vhost_net.h
> @@ -10,6 +10,7 @@ typedef struct vhost_net VHostNetState;
> typedef struct VhostNetOptions {
> VhostBackendType backend_type;
> NetClientState *net_backend;
> + uint32_t busyloop_timeout;
> void *opaque;
> } VhostNetOptions;
>
> diff --git a/net/tap.c b/net/tap.c
> index 740e8a2..7e28102 100644
> --- a/net/tap.c
> +++ b/net/tap.c
> @@ -663,6 +663,11 @@ static void net_init_tap_one(const NetdevTapOptions
> *tap, NetClientState *peer,
>
> options.backend_type = VHOST_BACKEND_TYPE_KERNEL;
> options.net_backend = &s->nc;
> + if (tap->has_vhost_poll_us) {
> + options.busyloop_timeout = tap->vhost_poll_us;
> + } else {
> + options.busyloop_timeout = 0;
> + }
>
> if (vhostfdname) {
> vhostfd = monitor_fd_param(cur_mon, vhostfdname, &err);
> @@ -686,8 +691,9 @@ static void net_init_tap_one(const NetdevTapOptions *tap,
> NetClientState *peer,
> "vhost-net requested but could not be initialized");
> return;
> }
> - } else if (vhostfdname) {
> - error_setg(errp, "vhostfd= is not valid without vhost");
> + } else if (vhostfdname || tap->has_vhost_poll_us) {
> + error_setg(errp, "vhostfd(s)= or vhost_poll_us= is not valid"
> + " without vhost");
> }
> }
>
> diff --git a/net/vhost-user.c b/net/vhost-user.c
> index 1b9e73a..b200182 100644
> --- a/net/vhost-user.c
> +++ b/net/vhost-user.c
> @@ -80,6 +80,7 @@ static int vhost_user_start(int queues, NetClientState
> *ncs[])
>
> options.net_backend = ncs[i];
> options.opaque = s->chr;
> + options.busyloop_timeout = 0;
> s->vhost_net = vhost_net_init(&options);
> if (!s->vhost_net) {
> error_report("failed to init vhost_net for queue %d", i);
> diff --git a/qapi-schema.json b/qapi-schema.json
> index 54634c4..8afdedf 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -2531,6 +2531,9 @@
> #
> # @queues: #optional number of queues to be created for multiqueue capable
> tap
> #
> +# @vhost-poll-us: #optional maximum number of microseconds that could
> +# be spent on busy polling for vhost net (since 2.7)
> +#
> # Since 1.2
> ##
> { 'struct': 'NetdevTapOptions',
> @@ -2547,7 +2550,8 @@
> '*vhostfd': 'str',
> '*vhostfds': 'str',
> '*vhostforce': 'bool',
> - '*queues': 'uint32'} }
> + '*queues': 'uint32',
> + '*vhost-poll-us': 'uint32'} }
>
> ##
> # @NetdevSocketOptions
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 587de8f..22ddb82 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -1569,6 +1569,7 @@ DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
> "-netdev
> tap,id=str[,fd=h][,fds=x:y:...:z][,ifname=name][,script=file][,downscript=dfile]\n"
> "
> [,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off]\n"
> "
> [,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n"
> + " [,vhost-poll-us=n]\n"
> " configure a host TAP network backend with ID 'str'\n"
> " use network scripts 'file' (default="
> DEFAULT_NETWORK_SCRIPT ")\n"
> " to configure it and 'dfile' (default="
> DEFAULT_NETWORK_DOWN_SCRIPT ")\n"
> @@ -1588,6 +1589,8 @@ DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
> " use 'vhostfd=h' to connect to an already opened vhost
> net device\n"
> " use 'vhostfds=x:y:...:z to connect to multiple already
> opened vhost net devices\n"
> " use 'queues=n' to specify the number of queues to be
> created for multiqueue TAP\n"
> + " use 'vhost-poll-us=n' to speciy the maximum number of
> microseconds that could be\n"
> + " spent on busy polling for vhost net\n"
> "-netdev bridge,id=str[,br=bridge][,helper=helper]\n"
> " configure a host TAP network backend with ID 'str' that
> is\n"
> " connected to a bridge (default="
> DEFAULT_BRIDGE_INTERFACE ")\n"