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From: Eric Dumazet <eric.dumazet@gmail.com>
To: Jiri Kosina <jkosina@suse.cz>
Cc: Adam McLaurin <lkml@irotas.net>,
	Will Newton <will.newton@gmail.com>,
	linux-kernel@vger.kernel.org, netdev <netdev@vger.kernel.org>
Subject: Re: Loopback and Nagle's algorithm
Date: Tue, 12 Apr 2011 15:08:23 +0200	[thread overview]
Message-ID: <1302613703.3233.40.camel@edumazet-laptop> (raw)
In-Reply-To: <alpine.LRH.2.00.1104121354010.6953@twin.jikos.cz>

Le mardi 12 avril 2011 à 13:54 +0200, Jiri Kosina a écrit :
> On Tue, 12 Apr 2011, Adam McLaurin wrote:
> 
> > > 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...

      parent reply	other threads:[~2011-04-12 13:08 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1302575869.13492.1440076201@webmail.messagingengine.com>
2011-04-12  9:42 ` Loopback and Nagle's algorithm Alejandro Riveira Fernández
     [not found] ` <BANLkTi=jpdLRc35DkBhLmUr8-P+ggcrgoA@mail.gmail.com>
     [not found]   ` <1302606246.21782.1440195277@webmail.messagingengine.com>
     [not found]     ` <alpine.LRH.2.00.1104121354010.6953@twin.jikos.cz>
2011-04-12 13:08       ` Eric Dumazet [this message]

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