On Thu, 25 Sep 2014 23:04:56 -0700
Eric Dumazet [off-list ref] wrote:

[...]

It turned out the problem was caused by compiler trying to be
smart, but involving a bad MESI transaction :

[...] 

I got an incredible 10 % gain [1] by making sure cpu do not attempt
to get the cache line in Shared mode, but directly requests for
ownership.

[...]

Signed-off-by: Eric Dumazet <edumazet@google.com>
---

I'm very impressed - thank you Eric for finding this!!!

Acked-by: Jesper Dangaard Brouer <redacted>

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