From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031625Ab2COQK6 (ORCPT ); Thu, 15 Mar 2012 12:10:58 -0400 Received: from merlin.infradead.org ([205.233.59.134]:35786 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031530Ab2COQK5 convert rfc822-to-8bit (ORCPT ); Thu, 15 Mar 2012 12:10:57 -0400 Message-ID: <1331827843.18960.197.camel@twins> Subject: Re: [PATCH] watchdog: Make sure the watchdog thread gets CPU on loaded system From: Peter Zijlstra To: Mandeep Singh Baines Cc: Don Zickus , Ingo Molnar , Andrew Morton , LKML , Michal Hocko Date: Thu, 15 Mar 2012 17:10:43 +0100 In-Reply-To: <20120315153907.GV27051@google.com> References: <1331757525-5755-1-git-send-email-dzickus@redhat.com> <20120314161906.e53359d3.akpm@linux-foundation.org> <20120315014511.GT27051@google.com> <1331809239.18960.168.camel@twins> <1331809597.18960.171.camel@twins> <20120315124228.GA5318@elte.hu> <1331820051.18960.187.camel@twins> <20120315143549.GC3941@redhat.com> <20120315153907.GV27051@google.com> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Mailer: Evolution 3.2.2- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2012-03-15 at 08:39 -0700, Mandeep Singh Baines wrote: > Its a good tool for catching problems of scale. As we move to more and > more cores you'll uncover bugs where data structures start to blow up. > Hash tables get huge, when you have 100000s of processes or millions > of > TCP flows, or cgroups or namespace. That critical section (spinlock, > spinlock_bh, or preempt_disable) that used to be OK might no longer > be. Or you run with the preempt latency tracer.