netdev - Re: [net-next PATCH v3 0/6] XDP for virtio

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Date:   Wed, 30 Nov 2016 20:56:02 +0200
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     John Fastabend <john.fastabend@...il.com>
Cc:     tgraf@...g.ch, shm@...ulusnetworks.com,
        alexei.starovoitov@...il.com, daniel@...earbox.net,
        davem@...emloft.net, john.r.fastabend@...el.com,
        netdev@...r.kernel.org, bblanco@...mgrid.com, brouer@...hat.com
Subject: Re: [net-next PATCH v3 0/6] XDP for virtio_net

On Wed, Nov 30, 2016 at 10:41:04AM -0800, John Fastabend wrote:
> On 16-11-30 10:35 AM, Michael S. Tsirkin wrote:
> > On Tue, Nov 29, 2016 at 12:05:20PM -0800, John Fastabend wrote:
> >> This implements virtio_net for the mergeable buffers and big_packet
> >> modes. I tested this with vhost_net running on qemu and did not see
> >> any issues. For testing num_buf > 1 I added a hack to vhost driver
> >> to only but 100 bytes per buffer.
> >>
> >> There are some restrictions for XDP to be enabled and work well
> >> (see patch 3) for more details.
> >>
> >>   1. LRO must be off
> >>   2. MTU must be less than PAGE_SIZE
> >>   3. queues must be available to dedicate to XDP
> >>   4. num_bufs received in mergeable buffers must be 1
> >>   5. big_packet mode must have all data on single page
> >>
> >> Please review any comments/feedback welcome as always.
> >>
> >> v2, fixes rcu usage throughout thanks to Eric and the use of
> >> num_online_cpus() usage thanks to Jakub.
> >>
> >> v3, add slowpath patch to handle num_bufs > 1
> >>
> >> Thanks,
> >> John
> > 
> > BTW this is threaded incorrectly: patch 1/6 isn't a reply to 0/6,
> > patches 2 and on are replies to patch 1.
> > 
> 
> Ah yep, if you mangle the command line git will send the
> cover letter even if you have mangled 'to' email addresses but when
> it hits a real patch it aborts. At least on my version of git.
> 
> > I'm busy until end of week, I'll review Monday. Sorry about the delay.
> 
> In the meantime I'll post a v4 with better commit message (Alexei) and
> address a corner cases Jakub pointed out.

I did a quick look and found some too, but a detailed review will
have to wait till next week.

> > 
> >> ---
> >>
> >> John Fastabend (6):
> >>       net: virtio dynamically disable/enable LRO
> >>       net: xdp: add invalid buffer warning
> >>       virtio_net: Add XDP support
> >>       virtio_net: add dedicated XDP transmit queues
> >>       virtio_net: add XDP_TX support
> >>       virtio_net: xdp, add slowpath case for non contiguous buffers
> >>
> >>
> >>  drivers/net/virtio_net.c |  344 +++++++++++++++++++++++++++++++++++++++++++++-
> >>  include/linux/filter.h   |    1 
> >>  net/core/filter.c        |    6 +
> >>  3 files changed, 346 insertions(+), 5 deletions(-)
> >>
> >> --
> >> Signature