From mboxrd@z Thu Jan 1 00:00:00 1970 From: jamal Subject: Re: NAPI, e100, and system performance problem Date: Wed, 20 Apr 2005 11:15:31 -0400 Message-ID: <1114010131.8916.65.camel@localhost.localdomain> References: <1113855967.7436.39.camel@localhost.localdomain> <20050419055535.GA12211@sgi.com> <20050419113657.7290d26e.davem@davemloft.net> <20050420145629.GH19415@sgi.com> Reply-To: hadi@cyberus.ca Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: "David S. Miller" , akepner@sgi.com, jesse.brandeburg@intel.com, netdev@oss.sgi.com Return-path: To: Greg Banks In-Reply-To: <20050420145629.GH19415@sgi.com> Sender: netdev-bounce@oss.sgi.com Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org On Thu, 2005-21-04 at 00:56 +1000, Greg Banks wrote: > We have a stats package called PCP (see oss.sgi.com) which samples > all kinds of stuff out of /proc at a configurable polling frequency, > default 2 sec, and provides scrolling graphs. We've also done some > profiling work using the SGI kernprof patch in 2.4 kernels and > oprofile in 2.6 kernels. > this may not be sufficient to debug; that PCP sounds like a hog in its own merit polling /proc. Actually, lets start by saying this: If you problem is PIO being too expensive on your machines, then the solution maybe for you to set coalescing parameters appropriately. This is a known issue - "fixing NAPI" requires complicating things for the majority who dont have the same problem as you. The issue pointed out by Rick Jones that you sacrifice latency is still valid. Additionaly, with many NICs in place, coalescing is not gonna cut it. Having said that - here are some items that will be useful to collect before and after a run: - netstat -s output - /proc/net/softnet_stat - ifconfig output - tc -s qdisc on the interfaces - oprofile - any other thing you could come up with like some of the stuff you posted recently on how many packets/interupt are processed with and without NAPI. - preferably run UDP tests so we dont have to think hard about stats like retransmits etc. - And as pointed by Dave, pick the latest kernel. cheers, jamal