From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754716AbXKVUaZ (ORCPT ); Thu, 22 Nov 2007 15:30:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752317AbXKVUaM (ORCPT ); Thu, 22 Nov 2007 15:30:12 -0500 Received: from www.tglx.de ([62.245.132.106]:33404 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752135AbXKVUaL (ORCPT ); Thu, 22 Nov 2007 15:30:11 -0500 Date: Thu, 22 Nov 2007 21:29:51 +0100 (CET) From: Thomas Gleixner To: Pavel Machek cc: Ingo Molnar , kernel list Subject: Re: nohz and strange sleep latencies In-Reply-To: <20071122185238.GA1821@elf.ucw.cz> Message-ID: References: <20071119203152.GA1772@elf.ucw.cz> <20071119205555.GA28696@elte.hu> <20071119211142.GA1857@elf.ucw.cz> <20071120085704.GA19950@elte.hu> <20071120105458.GA1597@elf.ucw.cz> <20071120205454.GD10008@elte.hu> <20071120225246.GA24380@elte.hu> <20071122185238.GA1821@elf.ucw.cz> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 22 Nov 2007, Pavel Machek wrote: > > but perhaps somehow we miss this fact and fail to turn off the lapic > > clockevents drivers? > > Ok, I guess I'm lost. If I offline second CPU, I immediately get > 1000Hz timer tick... is that expected? Hmm. No. I have no idea why this is happening. 34196 total events, 55.083 events/sec echo 0 >/sys/devices/system/cpu/cpu1/online 36073 total events, 54.679 events/sec > I'm trying to decide when system is idle (lets say that means "no user > task is scheduled to wakeup within 10 seconds)... I added some > instrumentation to nohz subsystem, but it does not behave like I'd > expect: even if I run "while true; do sleep .01; done" loop, I see > nohz preparing for 5 seconds sleep... while it seems obvious that it > can only be 10msec sleep, and with max_cstate=1, it works that > way... Plus, nte->start_pid seems to contain some random numbers :-(. > > What am I doing wrong? > > (Patch for illustration, I can generate full diff against vanilla, > but...) Just to make sure what we are hunting: Do you have the same problem with an non-pavel-tainted 2.6.24-rc3 ? tglx