Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751434AbWCJOoQ (ORCPT ); Fri, 10 Mar 2006 09:44:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751455AbWCJOoQ (ORCPT ); Fri, 10 Mar 2006 09:44:16 -0500 Received: from linux01.gwdg.de ([134.76.13.21]:5820 "EHLO linux01.gwdg.de") by vger.kernel.org with ESMTP id S1751434AbWCJOoQ (ORCPT ); Fri, 10 Mar 2006 09:44:16 -0500 Date: Fri, 10 Mar 2006 15:44:15 +0100 (MET) From: Jan Engelhardt To: Tomasz Chmielewski cc: linux-kernel@vger.kernel.org Subject: Re: can I bring Linux down by running "renice -20 cpu_intensive_process"? In-Reply-To: <441180DD.3020206@wpkg.org> Message-ID: References: <441180DD.3020206@wpkg.org> 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 Content-Length: 1651 Lines: 41 >Subject: can I bring Linux down by running "renice -20 cpu_intensive_process"? > Depends on what the cpu_intensive_process does. If it tries to allocate lots of memory, maybe. If it's _just_ CPU (as in `perl -e '1 while 1'`), you get a chance that you can input some commands on a terminal to kill it. SCHED_FIFO'ing or SCHED_RR'ing such a process is sudden death of course. > I have a Linux server (kernel 2.6.8.1 + Linux RAID1) which is a "backup" > machine: it gets the files from other servers, compresses it, writes to the > tape, checks md5sums etc. > > It's been running for quite a bit, no problems with stability so far. > Why would you need it to run at -20 anyway? > As I restarted the machine, I saw that the logging ends few minutes after I > changed the priority of md5sum to -20. > > So here is my question: is it possible to bring down the machine by simply > doing "renice -20 cpu_intensive_process"? > In case of md5sum: it should not be. At least you should have been able to unblank the console pressing any key, or have sysrq available. > As I said, this machine does heavy compression and md5sum calculations of big > files every day, and was stable all the time - but stopped responding after I > changed the priority of a CPU-intensive process to -20. > > Coincidence and a hardware failure? > Sysrq+T (and/or +P) will tell you where the CPU is running. Jan Engelhardt -- - 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/