Subject: Re: [PATCH 0/2] Get rid of ndo_xmit_flush

From: Jesper Dangaard Brouer <[email-masked]>
Date: Wed, 27 Aug 2014 15:56:51 +0200

On Wed, 27 Aug 2014 06:23:58 -0700
Eric Dumazet <[email-masked]> wrote:

> I am afraid Jesper tests are not complete to truly have a picture of the
> extra costs, because he made sure no false sharing was possible (A
> single cpu does everything and keeps skb in its cache)

I fully agree. My tests a very artificial benchmarks only for the
optimal case.

I do worry a bit, if writing skb->xmit_more in a more cache cold
scenarios could hurt us (as that cacheline seems to be read mostly),
but this is not a problem right now because it will always be cache
hot, as we always clear the entire SKB in alloc.

-- 
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