From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751364AbWFZCTP (ORCPT ); Sun, 25 Jun 2006 22:19:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751380AbWFZCTP (ORCPT ); Sun, 25 Jun 2006 22:19:15 -0400 Received: from mail.gmx.de ([213.165.64.21]:57262 "HELO mail.gmx.net") by vger.kernel.org with SMTP id S1751364AbWFZCTO (ORCPT ); Sun, 25 Jun 2006 22:19:14 -0400 X-Authenticated: #14349625 Subject: Re: [PATCH] i386: Fix softirq accounting with 4K stacks From: Mike Galbraith To: =?ISO-8859-1?Q?Bj=F6rn?= Steinbrink Cc: Arjan van de Ven , linux-kernel@vger.kernel.org, danial_thom@yahoo.com, Linus Torvalds , Andrew Morton In-Reply-To: <20060625184244.GA11921@atjola.homenet> References: <1151142716.7797.10.camel@Homer.TheSimpsons.net> <1151149317.7646.14.camel@Homer.TheSimpsons.net> <20060624154037.GA2946@atjola.homenet> <1151166193.8516.8.camel@Homer.TheSimpsons.net> <20060624192523.GA3231@atjola.homenet> <1151211993.8519.6.camel@Homer.TheSimpsons.net> <20060625111238.GB8223@atjola.homenet> <20060625142440.GD8223@atjola.homenet> <1151257451.7858.45.camel@Homer.TheSimpsons.net> <1151257397.4940.45.camel@laptopd505.fenrus.org> <20060625184244.GA11921@atjola.homenet> Content-Type: text/plain; charset=utf-8 Date: Mon, 26 Jun 2006 04:23:22 +0200 Message-Id: <1151288602.7470.22.camel@Homer.TheSimpsons.net> Mime-Version: 1.0 X-Mailer: Evolution 2.4.0 Content-Transfer-Encoding: 8bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2006-06-25 at 20:42 +0200, Björn Steinbrink wrote: > I just booted with both patches applied, mine and Mike's, and that > actually makes a difference in hardirq cpu time accounting. With my > patch only, hi is 0 in top while the box gets a ping flood. With both > patches, I get about 1% hi. Mike's patch causes update_process_times() > to be called twice on UP, but that alone shouldn't change the > percentages, right? Yes, you definitely need to comment out the other call if you test the SMP path on UP+IO-APIC. > OTOH top shows "hi" as zero with 8K stacks as well unless Mike's patch > is applied, so the results with Mike's patch are bogus (if so, why?) or > hardirq accounting is broken in general. Something is certainly still b0rken. I still get three different answers to the question "what is my cpu usage" depending on configuration. With stock UP kernel with no IO-APIC, interrupt load is all hi. With your patch and IO-APIC, it's all si. SMP shows a mix of both. I like the result of using the SMP path if you have an IO-APIC best, though I haven't verified them against a profile for accuracy. Taking a peek at the profile confirms that it is indeed mixed, so anything showing the load as being either hi or si has to be wrong. -Mike