Re: Loopback and Nagle's algorithm

Le mardi 12 avril 2011 à 13:54 +0200, Jiri Kosina a écrit :

On Tue, 12 Apr 2011, Adam McLaurin wrote:

quoted

quoted

It may be caused by an increase in context switch rate, as both sender
and receiver are on the same machine.

I'm not sure that's what's happening, since the box where I'm running
this test has 8 physical CPU's and 32 cores in total.

Have you tried firing up the testcase under perf, to see what it reveals 
as the bottleneck?

CC netdev

This rings a bell here.

I suspect we hit mod_timer() / lock_timer_base()  because of delack
timer constantly changing.

I remember raising this point last year :

http://kerneltrap.org/mailarchive/linux-netdev/2010/5/20/6277741

David answer : 
http://kerneltrap.org/mailarchive/linux-netdev/2010/6/2/6278430

I am afraid no change was done...