From mboxrd@z Thu Jan 1 00:00:00 1970 From: "David S. Miller" Subject: Re: NAPI and CPU utilization [was: NAPI, e100, and system performance problem] Date: Tue, 19 Apr 2005 14:09:51 -0700 Message-ID: <20050419140951.20965099.davem@davemloft.net> References: <1113855967.7436.39.camel@localhost.localdomain> <20050419055535.GA12211@sgi.com> <20050419113657.7290d26e.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: gnb@sgi.com, hadi@cyberus.ca, jesse.brandeburg@intel.com, netdev@oss.sgi.com Return-path: To: Arthur Kepner In-Reply-To: Sender: netdev-bounce@oss.sgi.com Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org Please don't expect us to take the table of numbers seriously when it's against a more than year old kernel and without a patch you know and even explicitly mention makes this case perform significantly better. I understand your basic premise, but you're asking us to evaluate known stale performance data. Can you please get numbers against current 2.6.x kernels? It is likely that people don't care so much about this because on most systems the PIO overhead is not so pronounced as it is on your enormous Altix systems. On PCI-E and the onboard Intel e1000 stuff, PIOs are incredibly cheap (Robert Olsson posted some nice numbers not too long ago). So what I'm saying is that the numbers probably don't fall much this way on non-Altix systems. But that doesn't mean we shouldn't start using hw coalescing a little bit even with NAPI, I think we should.