From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753247AbYIQHkS (ORCPT ); Wed, 17 Sep 2008 03:40:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750879AbYIQHkG (ORCPT ); Wed, 17 Sep 2008 03:40:06 -0400 Received: from main.gmane.org ([80.91.229.2]:43748 "EHLO ciao.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750706AbYIQHkF (ORCPT ); Wed, 17 Sep 2008 03:40:05 -0400 X-Injected-Via-Gmane: http://gmane.org/ To: linux-kernel@vger.kernel.org From: Andrew Paprocki Subject: Re: [RFC PATCH 0/1]: timers: Timer Migration Date: Wed, 17 Sep 2008 07:35:04 +0000 (UTC) Message-ID: References: <20080916091219.GA1068@linux.vnet.ibm.com> <1221566730.6943.16.camel@lappy.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: main.gmane.org User-Agent: Loom/3.14 (http://gmane.org/) X-Loom-IP: 76.15.153.58 (Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.8.1.15; .NET CLR 3.5; ffco7) Gecko/20080623 Firefox/2.0.0.15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Peter Zijlstra chello.nl> writes: > This seems like an exceedingly dumb idea - cpu 0 might be a long long > way from x and by pushing all timers to cpu0 you might actually overload > cpu 0. You have to give credit to Solaris for doing that first :). They implemented usleep() using nanosleep() which uses the kernel callout queue. That queue is single threaded and only processed on CPU0 in the clock interrupt handler, causing CPU0 to spin 100% if enough calls to usleep() are made across the system. http://bugs.opensolaris.org/view_bug.do?bug_id=6565503 -Andrew