Hi Maxime,
Thanks for your comment, please see below.
> -----Original Message-----
> From: Maxime Coquelin [mailto:maxime.coque...@redhat.com]
> Sent: Wednesday, June 19, 2019 12:10 PM
> To: Noa Ezra <n...@mellanox.com>
> Cc: Matan Azrad <ma...@mellanox.com>; dev@dpdk.org
> Subject: Re: [PATCH 2/2] net/vhost: support mrg-rxbuf disabling
>
> Hi Noa,
>
> On 6/19/19 8:13 AM, Noa Ezra wrote:
> > Rx mergeable buffers is a virtio feature that allows chaining of
> > multiple virtio descriptors to handle large packet size.
> > This behavior is supported and enabled by default, however in case the
> > user knows that rx mergeable buffers are not needed, he can disable
> > the feature.
> > The user should also set mrg_rxbuf=off in virtual machine's xml.
>
> I'm not sure to understand why it is needed, as the vhost-user library
> supports the feature, it's better to let it being advertised.
>
> As you say, it is up to the user to disable it in the VM's XML.
> Done this way, the feature won't be negotiated.
>
I agree with you, I'll remove this patch from the series.
> Moreover, the proposal deadline for v19.08 is over by more than 2 weeks.
I'm sorry, the mail was sent a long time but didn't get to the mailing list.
In any case, I'll prepare a new patch with only TSO (the first patch) and send
it to the next release.
> Maxime
>
> > Signed-off-by: Noa Ezra <n...@mellanox.com>
> > Reviewed-by: Matan Azrad <ma...@mellanox.com>
> > ---
> > doc/guides/nics/vhost.rst | 5 +++++
> > drivers/net/vhost/rte_eth_vhost.c | 17 ++++++++++++++++-
> > 2 files changed, 21 insertions(+), 1 deletion(-)
> >
> > diff --git a/doc/guides/nics/vhost.rst b/doc/guides/nics/vhost.rst
> > index 8cfda4d..2a455b5 100644
> > --- a/doc/guides/nics/vhost.rst
> > +++ b/doc/guides/nics/vhost.rst
> > @@ -81,6 +81,11 @@ The user can specify below arguments in `--vdev`
> option.
> > It is used to disable tso support in vhost library.
> > (Default: 1 (enabled))
> >
> > +#. ``mrg-rxbuf``:
> > +
> > + It is used to disable mrg rxbuf support in vhost library.
> > + (Default: 1 (enabled))
> > +
> > Vhost PMD event handling
> > ------------------------
> >
> > diff --git a/drivers/net/vhost/rte_eth_vhost.c
> > b/drivers/net/vhost/rte_eth_vhost.c
> > index a38c235..9a54020 100644
> > --- a/drivers/net/vhost/rte_eth_vhost.c
> > +++ b/drivers/net/vhost/rte_eth_vhost.c
> > @@ -32,6 +32,7 @@
> > #define ETH_VHOST_IOMMU_SUPPORT "iommu-support"
> > #define ETH_VHOST_POSTCOPY_SUPPORT "postcopy-support"
> > #define ETH_VHOST_VIRTIO_NET_F_HOST_TSO "tso"
> > +#define ETH_VHOST_VIRTIO_NET_F_MRG_RXBUF "mrg-rxbuf"
> > #define VHOST_MAX_PKT_BURST 32
> >
> > static const char *valid_arguments[] = { @@ -42,6 +43,7 @@
> > ETH_VHOST_IOMMU_SUPPORT,
> > ETH_VHOST_POSTCOPY_SUPPORT,
> > ETH_VHOST_VIRTIO_NET_F_HOST_TSO,
> > + ETH_VHOST_VIRTIO_NET_F_MRG_RXBUF,
> > NULL
> > };
> >
> > @@ -1348,6 +1350,7 @@ struct vhost_xstats_name_off {
> > int iommu_support = 0;
> > int postcopy_support = 0;
> > int tso = 1;
> > + int mrg_rxbuf = 1;
> > struct rte_eth_dev *eth_dev;
> > const char *name = rte_vdev_device_name(dev);
> >
> > @@ -1442,6 +1445,17 @@ struct vhost_xstats_name_off {
> > }
> > }
> >
> > + if (rte_kvargs_count(kvlist,
> ETH_VHOST_VIRTIO_NET_F_MRG_RXBUF) == 1) {
> > + ret = rte_kvargs_process(kvlist,
> > + ETH_VHOST_VIRTIO_NET_F_MRG_RXBUF,
> > + &open_int, &mrg_rxbuf);
> > + if (ret < 0)
> > + goto out_free;
> > +
> > + if (mrg_rxbuf == 0)
> > + disable_flags |= (1ULL <<
> VIRTIO_NET_F_MRG_RXBUF);
> > + }
> > +
> > if (dev->device.numa_node == SOCKET_ID_ANY)
> > dev->device.numa_node = rte_socket_id();
> >
> > @@ -1494,7 +1508,8 @@ struct vhost_xstats_name_off {
> > "dequeue-zero-copy=<0|1> "
> > "iommu-support=<0|1> "
> > "postcopy-support=<0|1> "
> > - "tso=<0|1>");
> > + "tso=<0|1> "
> > + "mrg-rxbuf=<0|1>");
> >
> > RTE_INIT(vhost_init_log)
> > {
> >
