From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752012Ab0IFFdW (ORCPT ); Mon, 6 Sep 2010 01:33:22 -0400 Received: from mailhost-x2-m4.netultra.net ([78.40.49.234]:62281 "EHLO smtp-delay2.nerim.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751754Ab0IFFdT (ORCPT ); Mon, 6 Sep 2010 01:33:19 -0400 Date: Mon, 6 Sep 2010 07:32:55 +0200 From: Damien Wyart To: Nix Cc: linux-kernel@vger.kernel.org Subject: Re: 2.6.35.*: horrible (exponential? >linear) slowdown to unusability (ACPI idle?) Message-ID: <20100906053255.GA23340@brouette> References: <87zkvx2ese.fsf@spindle.srvr.nix> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87zkvx2ese.fsf@spindle.srvr.nix> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, * Nix [2010-09-05 01:51]: > This is a preliminary report: I haven't bisected this problem yet, or > isolated it in any significant fashion. > What I can say is this. > In 2.6.35.3, but not in 2.6.34.1, some of my systems experience an > increasingly severe series of stalls whenever the system is idle. The > stalls get worse at a rate above linear: about fifty seconds after they > start, I am waiting five to ten seconds for responses to keystrokes. It > is very hard to get anything much done in this situation: even > restarting is hard. 'perf top' shows nothing using the time, but the > load average is pegged at 1. > I can verify that this does not happen on my embedded Geode box, a > 32-bit system without ACPI support. It does happen on my x86-64 systems, > all of which are running 64-bit kernels with ACPI. These systems are all > running with CONFIG_NOHZ, so I tried turning it off. The problem got > enormously worse: the kernel lasted 6.4 seconds after initial boot and > about two seconds after entering userspace before stalling completely. I think this is related to what has been discussed in this thread: http://lkml.org/lkml/2010/7/14/11 I've not seen the problem with 2.6.35.4 yet, and only once with 2.6.35.3. Zeno said it disappeared for him when he started to use 2.6.35-stable. So if you can reproduce it quite easily, I guess bisection (even painful) will be the best way to get (hopefuly) an idea of where the problem might come from... -- Damien Wyart