[libvirt] [PATCH] qemuBuildNicDevStr: Add mq=on for multiqueue networking

[Laine Stump]

On 08/22/2013 04:36 AM, Michal Privoznik wrote:
> If user requested multiqueue networking, beside multiple /dev/tap and
> /dev/vhost-net openings, we forgot to pass mq=on onto the -device
> virtio-net-pci command line. This is advised at:
>
>   http://www.linux-kvm.org/page/Multiqueue#Enable_MQ_feature
> ---
>
> Notes:
>     Maybe worth backporting to maintainer branches too. The MQ was introduced in
>     the 1.0.6 release.
>
>  src/qemu/qemu_command.c | 7 ++++++-
>  src/qemu/qemu_command.h | 1 +
>  src/qemu/qemu_hotplug.c | 4 +++-
>  3 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> index f151173..d73872a 100644
> --- a/src/qemu/qemu_command.c
> +++ b/src/qemu/qemu_command.c
> @@ -4730,6 +4730,7 @@ qemuBuildNicDevStr(virDomainDefPtr def,
>                     virDomainNetDefPtr net,
>                     int vlan,
>                     int bootindex,
> +                   bool multiqueue,
>                     virQEMUCapsPtr qemuCaps)
>  {
>      virBuffer buf = VIR_BUFFER_INITIALIZER;
> @@ -4782,6 +4783,8 @@ qemuBuildNicDevStr(virDomainDefPtr def,
>                                virDomainVirtioEventIdxTypeToString(net->driver.virtio.event_idx));
>          }
>      }
> +    if (usingVirtio && multiqueue)
> +        virBufferAddLit(&buf, ",mq=on");
>      if (vlan == -1)
>          virBufferAsprintf(&buf, ",netdev=host%s", net->info.alias);
>      else
> @@ -7275,7 +7278,9 @@ qemuBuildInterfaceCommandLine(virCommandPtr cmd,
>          virCommandAddArgList(cmd, "-netdev", host, NULL);
>      }
>      if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE)) {
> -        if (!(nic = qemuBuildNicDevStr(def, net, vlan, bootindex, qemuCaps)))
> +        bool multiqueue = tapfdSize > 1 || vhostfdSize > 1;
> +        if (!(nic = qemuBuildNicDevStr(def, net, vlan, bootindex,

usually we put a blank line between variable declarations and code.

> +                                       multiqueue, qemuCaps)))
>              goto cleanup;
>          virCommandAddArgList(cmd, "-device", nic, NULL);
>      } else {
> diff --git a/src/qemu/qemu_command.h b/src/qemu/qemu_command.h
> index 5c5c025..a9854a3 100644
> --- a/src/qemu/qemu_command.h
> +++ b/src/qemu/qemu_command.h
> @@ -102,6 +102,7 @@ char * qemuBuildNicDevStr(virDomainDefPtr def,
>                            virDomainNetDefPtr net,
>                            int vlan,
>                            int bootindex,
> +                          bool multiqueue,
>                            virQEMUCapsPtr qemuCaps);
>  
>  char *qemuDeviceDriveHostAlias(virDomainDiskDefPtr disk,
> diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
> index 478f331..b49073b 100644
> --- a/src/qemu/qemu_hotplug.c
> +++ b/src/qemu/qemu_hotplug.c
> @@ -859,7 +859,9 @@ int qemuDomainAttachNetDevice(virConnectPtr conn,
>      }
>  
>      if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_DEVICE)) {
> -        if (!(nicstr = qemuBuildNicDevStr(vm->def, net, vlan, 0, priv->qemuCaps)))
> +        bool multiqueue = tapfdSize > 1 || vhostfdSize > 1;
> +        if (!(nicstr = qemuBuildNicDevStr(vm->def, net, vlan, 0,

Same comment here.

ACK with those two blank lines added.

> +                                          multiqueue, priv->qemuCaps)))
>              goto try_remove;
>      } else {
>          if (!(nicstr = qemuBuildNicStr(net, NULL, vlan)))