Re: [PATCH v3 bpf-next 2/2] veth: Support bulk XDP_TX

[Jesper Dangaard Brouer <brouer@redhat.com>]

On Thu, 13 Jun 2019 18:39:59 +0900
Toshiaki Makita <toshiaki.makita1@gmail.com> wrote:

> XDP_TX is similar to XDP_REDIRECT as it essentially redirects packets to
> the device itself. XDP_REDIRECT has bulk transmit mechanism to avoid the
> heavy cost of indirect call but it also reduces lock acquisition on the
> destination device that needs locks like veth and tun.
> 
> XDP_TX does not use indirect calls but drivers which require locks can
> benefit from the bulk transmit for XDP_TX as well.
> 
> This patch introduces bulk transmit mechanism in veth using bulk queue
> on stack, and improves XDP_TX performance by about 9%.
> 
> Here are single-core/single-flow XDP_TX test results. CPU consumptions
> are taken from "perf report --no-child".
> 
> - Before:
> 
>   7.26 Mpps
> 
>   _raw_spin_lock  7.83%
>   veth_xdp_xmit  12.23%
> 
> - After:
> 
>   7.94 Mpps
> 
>   _raw_spin_lock  1.08%
>   veth_xdp_xmit   6.10%
> 
> v2:
> - Use stack for bulk queue instead of a global variable.
> 
> Signed-off-by: Toshiaki Makita <toshiaki.makita1@gmail.com>
> ---
>  drivers/net/veth.c | 60 +++++++++++++++++++++++++++++++++++++++++++-----------
>  1 file changed, 48 insertions(+), 12 deletions(-)

Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer