Subject: Re: README: [PATCH RFC 11/11] net/mlx5e: XDP TX xmit more

From: Jesper Dangaard Brouer via iovisor-dev <iovisor-dev-9jONkmmOlFHEE9lA1F8Ukti2O/[email-masked]>
Date: Tue, 13 Sep 2016 18:47:38 +0200

On Tue, 13 Sep 2016 08:58:30 -0700
Eric Dumazet <[email-masked]> wrote:

> We also care about icache pressure, and GRO/TSO already provides
> bundling where it is applicable, without adding insane complexity in
> the stacks.

Sorry, I cannot resist. The GRO code is really bad regarding icache
pressure/usage, due to how everything is function pointers calling
function pointers, even if the general case is calling the function
defined just next to it in the same C-file (which usually cause
inlining).  I can easily get 10% more performance for UDP use-cases by
simply disabling the GRO code, and I measure a significant drop in
icache-misses.

Edward's solution should lower icache pressure.

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