Re: [Qemu-devel] [RFC] net: 'Remove vhostforce option in addition to vhost param'

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Feb 12, 2015 at 11:50:05AM +0530, Pankaj Gupta wrote:
>  vhostforce was added to enable use of vhost when
>  guest don't have MSI-X support.
>  Now, we have scenarios which  dont use interrupts
>  like DPDK and still use vhost. Also, performance of
>  guests without MSI-X support is getting less popular.
> 
>  Its ok to remove this extra option and enable vhost
>  on the basis of vhost=ON/OFF.
> 
> Signed-off-by: Pankaj Gupta <pagupta@redhat.com>

The patch doesn't seem to do what it says.
Did you try with a non MSIX guest and vhost=on, to check that
it actually runs vhost and not userspace virtio?

> ---
>  net/tap.c        |  4 +---
>  net/vhost-user.c | 16 ++--------------
>  2 files changed, 3 insertions(+), 17 deletions(-)
> 
> diff --git a/net/tap.c b/net/tap.c
> index 1fe0edf..bd2efa9 100644
> --- a/net/tap.c
> +++ b/net/tap.c
> @@ -634,13 +634,11 @@ static int net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
>          }
>      }
>  
> -    if (tap->has_vhost ? tap->vhost :
> -        vhostfdname || (tap->has_vhostforce && tap->vhostforce)) {
> +    if (tap->has_vhost ? tap->vhost : vhostfdname) {
>          VhostNetOptions options;
>  
>          options.backend_type = VHOST_BACKEND_TYPE_KERNEL;
>          options.net_backend = &s->nc;
> -        options.force = tap->has_vhostforce && tap->vhostforce;
>  
>          if (tap->has_vhostfd || tap->has_vhostfds) {
>              vhostfd = monitor_handle_fd_param(cur_mon, vhostfdname);
> diff --git a/net/vhost-user.c b/net/vhost-user.c
> index 24e050c..d2d7bf2 100644
> --- a/net/vhost-user.c
> +++ b/net/vhost-user.c
> @@ -18,7 +18,6 @@
>  typedef struct VhostUserState {
>      NetClientState nc;
>      CharDriverState *chr;
> -    bool vhostforce;
>      VHostNetState *vhost_net;
>  } VhostUserState;
>  
> @@ -51,7 +50,6 @@ static int vhost_user_start(VhostUserState *s)
>      options.backend_type = VHOST_BACKEND_TYPE_USER;
>      options.net_backend = &s->nc;
>      options.opaque = s->chr;
> -    options.force = s->vhostforce;
>  
>      s->vhost_net = vhost_net_init(&options);
>  
> @@ -133,8 +131,7 @@ static void net_vhost_user_event(void *opaque, int event)
>  }
>  
>  static int net_vhost_user_init(NetClientState *peer, const char *device,
> -                               const char *name, CharDriverState *chr,
> -                               bool vhostforce)
> +                               const char *name, CharDriverState *chr)
>  {
>      NetClientState *nc;
>      VhostUserState *s;
> @@ -149,7 +146,6 @@ static int net_vhost_user_init(NetClientState *peer, const char *device,
>      /* We don't provide a receive callback */
>      s->nc.receive_disabled = 1;
>      s->chr = chr;
> -    s->vhostforce = vhostforce;
>  
>      qemu_chr_add_handlers(s->chr, NULL, NULL, net_vhost_user_event, s);
>  
> @@ -230,7 +226,6 @@ int net_init_vhost_user(const NetClientOptions *opts, const char *name,
>  {
>      const NetdevVhostUserOptions *vhost_user_opts;
>      CharDriverState *chr;
> -    bool vhostforce;
>  
>      assert(opts->kind == NET_CLIENT_OPTIONS_KIND_VHOST_USER);
>      vhost_user_opts = opts->vhost_user;
> @@ -247,12 +242,5 @@ int net_init_vhost_user(const NetClientOptions *opts, const char *name,
>          return -1;
>      }
>  
> -    /* vhostforce for non-MSIX */
> -    if (vhost_user_opts->has_vhostforce) {
> -        vhostforce = vhost_user_opts->vhostforce;
> -    } else {
> -        vhostforce = false;
> -    }
> -
> -    return net_vhost_user_init(peer, "vhost_user", name, chr, vhostforce);
> +    return net_vhost_user_init(peer, "vhost_user", name, chr);
>  }
> -- 
> 1.8.3.1