From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759893AbZEGPbP (ORCPT ); Thu, 7 May 2009 11:31:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754232AbZEGPa6 (ORCPT ); Thu, 7 May 2009 11:30:58 -0400 Received: from smtp3.ultrahosting.com ([74.213.175.254]:47831 "EHLO smtp.ultrahosting.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751636AbZEGPa5 (ORCPT ); Thu, 7 May 2009 11:30:57 -0400 Date: Thu, 7 May 2009 11:20:06 -0400 (EDT) From: Christoph Lameter X-X-Sender: cl@qirst.com To: Alan Cox cc: Alok Kataria , "H. Peter Anvin" , Ingo Molnar , Thomas Gleixner , the arch/x86 maintainers , LKML Subject: Re: [PATCH] x86: Reduce the default HZ value In-Reply-To: <20090507161440.5b9c067d@lxorguk.ukuu.org.uk> Message-ID: References: <1241462661.412.8.camel@alok-dev1> <4A00ADDE.9000908@zytor.com> <1241560625.8665.17.camel@alok-dev1> <20090507161440.5b9c067d@lxorguk.ukuu.org.uk> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 7 May 2009, Alan Cox wrote: > The tick also still appears to be involved in ntp and in cpu stats where > a 50Hz tick would mean only 25Hz accuracy on CPU usage etc That could be fixed. If a thread is running then its using the processor and that does not change as long as it runs. That alone is enough to calculate cpu usage. Only if we want to examine the cpu state periodically while its running (profiling) then we would have a justification for interrupting the thread.