From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Chapman Subject: Re: RFC: possible NAPI improvements to reduce interrupt rates for low traffic rates Date: Thu, 06 Sep 2007 17:07:38 +0100 Message-ID: <46E025CA.50704@katalix.com> References: <200709061416.l86EG0Vb017675@quickie.katalix.com> <20070906153700.57a0c448@oldman> <46E01D16.5000609@katalix.com> <20070906163703.4fc12d32@oldman> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, hadi@cyberus.ca, davem@davemloft.net, jeff@garzik.org, mandeep.baines@gmail.com, ossthema@de.ibm.com To: Stephen Hemminger Return-path: Received: from s36.avahost.net ([74.53.95.194]:52400 "EHLO s36.avahost.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756483AbXIFQHm (ORCPT ); Thu, 6 Sep 2007 12:07:42 -0400 In-Reply-To: <20070906163703.4fc12d32@oldman> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Stephen Hemminger wrote: > On Thu, 06 Sep 2007 16:30:30 +0100 > James Chapman wrote: > >> Stephen Hemminger wrote: >> >>> What about the latency that NAPI imposes? Right now there are certain applications that >>> don't like NAPI because it add several more microseconds, and this may make it worse. >> >> Latency is something that I think this approach will actually improve, >> at the expense of additional polling. Or is it the ksoftirqd scheduling >> latency that you are referring to? > > The problem is that you leave interrupts disabled, right. Are you saying NAPI drivers should avoid keeping interrupts disabled? > Also you are busy during idle which kills powersaving and no hz clock. But perhaps some environments don't care about powersave because they are always busy? Embedded routers or network servers, for example. -- James Chapman Katalix Systems Ltd http://www.katalix.com Catalysts for your Embedded Linux software development