Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753012Ab3EIJUT (ORCPT ); Thu, 9 May 2013 05:20:19 -0400 Received: from mail-ee0-f52.google.com ([74.125.83.52]:42450 "EHLO mail-ee0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751881Ab3EIJUR (ORCPT ); Thu, 9 May 2013 05:20:17 -0400 Date: Thu, 9 May 2013 11:20:13 +0200 From: Ingo Molnar To: Frederic Weisbecker Cc: Dave Jones , "Paul E. McKenney" , Linux Kernel Subject: Re: rcu_preempt running flat out on idle desktop. Message-ID: <20130509092013.GA21620@gmail.com> References: <20130508203042.GA18895@redhat.com> <20130508205258.GN3648@linux.vnet.ibm.com> <20130508205633.GB18895@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1925 Lines: 41 * Frederic Weisbecker wrote: > 2013/5/8 Dave Jones : > > On Wed, May 08, 2013 at 01:52:58PM -0700, Paul E. McKenney wrote: > > > On Wed, May 08, 2013 at 04:30:42PM -0400, Dave Jones wrote: > > > > > > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND > > > > 10 root 20 0 0 0 0 S 200.0 0.0 185301:36 rcu_preempt > > > > 553 root 20 0 268m 76m 6764 S 200.0 2.6 144579:53 Xorg > > > > 1199 root 20 0 0 0 0 S 200.0 0.0 306:17.85 kworker/1:0 > > > > 501 root 20 0 0 0 0 S 200.0 0.0 4471:03 kworker/0:2 > > > > 12 root 20 0 0 0 0 S 200.0 0.0 67277:16 rcuop/1 > > > > 1237 davej 20 0 535m 15m 8484 S 200.0 0.5 3645:16 Terminal > > > > 859 davej 20 0 117m 3036 1336 S 200.0 0.1 1986:55 htop > > > > > > > > There are a lot of processes allegedly using "200%" of CPU time, a handful > > > > in the "196%" range, and then a bunch at 0. > > > > > > Yow!!! 185301 minutes is 128 days, which is a truly impressive amount of > > > CPU time to accumulate in a few short hours. > > Right, Ingo has reported something about strange high numbers in top > too. I need to investigate that. For CPU-intense loops I have seen a small anomaly with "slightly higher CPU usage numbers" - sometimes going to 101% or so but still converging to around 99.9% in the long run. The 200% bug pasted by Dave here seems to be very big and seems to affect all tasks not just true CPU-loopers. So I'd suggest reproducing and fixing Dave's bug first - that might fix the small anomaly I've seen. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/