From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kenny Chang Subject: Re: Multicast packet loss Date: Tue, 03 Feb 2009 10:20:13 -0500 Message-ID: <498860AD.5010702@athenacr.com> References: <49833DBC.7040607@athenacr.com> <20090130200330.GA12659@hmsreliant.think-freely.org> <49837F56.2020502@athenacr.com> <49838213.90700@cosmosbay.com> <20090131160333.GC23100@localhost.localdomain> <498723D9.5020509@athenacr.com> <20090203115502.GB28117@hmsreliant.think-freely.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE To: netdev@vger.kernel.org Return-path: Received: from [64.95.46.209] ([64.95.46.209]:1125 "EHLO sprinkles.inp.in.athenacr.com" rhost-flags-FAIL-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1752280AbZBCPUT (ORCPT ); Tue, 3 Feb 2009 10:20:19 -0500 Received: from [192.168.14.21] (fiji.em.in.athenacr.com [192.168.14.21]) by sprinkles.inp.in.athenacr.com (Postfix) with ESMTP id CC26B4B921 for ; Tue, 3 Feb 2009 10:20:15 -0500 (EST) In-Reply-To: <20090203115502.GB28117@hmsreliant.think-freely.org> Sender: netdev-owner@vger.kernel.org List-ID: Neil Horman wrote: > On Mon, Feb 02, 2009 at 11:48:25AM -0500, Kenny Chang wrote: > =20 >> Neil Horman wrote: >> =20 >>> On Fri, Jan 30, 2009 at 11:41:23PM +0100, Eric Dumazet wrote: >>> =20 >>> =20 >>>> Kenny Chang a =E9crit : >>>> =20 >>>> =20 >>>>> Ah, sorry, here's the test program attached. >>>>> >>>>> We've tried 2.6.28.1, but no, we haven't tried the 2.6.28.2 or th= e >>>>> 2.6.29.-rcX. >>>>> >>>>> Right now, we are trying to step through the kernel versions unti= l we >>>>> see where the performance drops significantly. We'll try 2.6.29-= rc soon >>>>> and post the result. >>>>> =20 >>>>> =20 >>>> 2.6.29-rc contains UDP receive improvements (lockless) >>>> >>>> Problem is multicast handling was not yet updated, but could be :) >>>> >>>> >>>> I was asking you "cat /proc/interrupts" because I believe you migh= t >>>> have a problem NIC interrupts being handled by one CPU only (when = having problems) >>>> >>>> =20 >>>> =20 >>> That would be expected (if irqbalance is running), and desireable, = since >>> spreading high volume interrupts like NICS accross multiple cores (= or more >>> specifically multiple L2 caches), is going increase your cache line= miss rate >>> significantly and decrease rx throughput. >>> >>> Although you do have a point here, if the system isn't running irqb= alance, and >>> the NICS irq affinity is spread accross multiple L2 caches, that wo= uld be a >>> point of improvement performance-wise. =20 >>> >>> Kenny, if you could provide the /proc/interrupts info along with /p= roc/cpuinfo >>> and your stats that I asked about earlier, that would be a big help= =2E >>> >>> Regards >>> Neil >>> >>> =20 >>> =20 >> This is for a working setup. >> >> =20 > > Are these quad core systems? Or dual core w/ hyperthreading? I ask = because in > your working setup you have 1/2 the number of cpus' and was not sure = if you > removed an entire package of if you just disabled hyperthreading. > > > Neil > > =20 Yeah, these are quad core systems. The 8 cpu system is a dual-processo= r=20 quad-core. The other is my desktop, single cpu quad core. Kenny