From mboxrd@z Thu Jan 1 00:00:00 1970 From: jamal Subject: Re: [RFC] New driver API to speed up small packets xmits Date: Thu, 10 May 2007 12:08:11 -0400 Message-ID: <1178813291.4062.32.camel@localhost> References: <20070510150833.GB24898@2ka.mipt.ru> <20070510154804.GA17474@2ka.mipt.ru> Reply-To: hadi@cyberus.ca Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Krishna Kumar2 , netdev@vger.kernel.org To: Evgeniy Polyakov Return-path: Received: from wx-out-0506.google.com ([66.249.82.238]:50894 "EHLO wx-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754866AbXEJQIP (ORCPT ); Thu, 10 May 2007 12:08:15 -0400 Received: by wx-out-0506.google.com with SMTP id h31so588950wxd for ; Thu, 10 May 2007 09:08:14 -0700 (PDT) In-Reply-To: <20070510154804.GA17474@2ka.mipt.ru> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, 2007-10-05 at 19:48 +0400, Evgeniy Polyakov wrote: > IMHO if you do not see in profile anything related to driver's xmit > function, it does not require to be fixed. True, but i think there may be value in amortizing the cost towards the driver. i.e If you grab a lock and send X packets vs a single packet, depending on the cost of the lock you may observe a reduction in CPU. I have tried similar experiments in the past and observed zero improvements in sane machines, but huge improvements on insane machines. Slides on my work here (just jump to about slide 93): http://vger.kernel.org/jamal_netconf2006.sxi One thought i had at the time was perhaps the e1000 DMA setup/teardown was very inefficient. As the slides indicate i was trying to get throughput improvements but failed to seen any on sane machines. A suggestion made to me was to look at CPU utilization as a metric. Unfortunately i havent had any chance yet. cheers, jamal