From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762944AbZEGWQx (ORCPT ); Thu, 7 May 2009 18:16:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755022AbZEGWQj (ORCPT ); Thu, 7 May 2009 18:16:39 -0400 Received: from byss.tchmachines.com ([208.76.80.75]:56978 "EHLO byss.tchmachines.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1763349AbZEGWQi (ORCPT ); Thu, 7 May 2009 18:16:38 -0400 Date: Thu, 7 May 2009 15:16:28 -0700 From: Ravikiran G Thirumalai To: Alan Cox Cc: Chris Snook , akataria@vmware.com, "H. Peter Anvin" , Ingo Molnar , Thomas Gleixner , the arch/x86 maintainers , LKML Subject: Re: [PATCH] x86: Reduce the default HZ value Message-ID: <20090507221628.GI6377@localdomain> References: <1241462661.412.8.camel@alok-dev1> <4A00ADDE.9000908@zytor.com> <1241560625.8665.17.camel@alok-dev1> <13a12eea0905070935o5abbeb49n8320d06c15b19b56@mail.gmail.com> <1241715373.32495.21.camel@alok-dev1> <13a12eea0905071329s79fb262tf89ed901a77726ae@mail.gmail.com> <20090507213403.3a75a6fb@lxorguk.ukuu.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090507213403.3a75a6fb@lxorguk.ukuu.org.uk> User-Agent: Mutt/1.5.15+20070412 (2007-04-11) X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - byss.tchmachines.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - scalex86.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 07, 2009 at 09:34:03PM +0100, Alan Cox wrote: >> >> Given your use case, what you really need to do is get Red Hat, >> >> Novell, et al. on the phone and ask them to ship kernels with HZ=100, >> >> because the distributions do their own thing anyway. > >As a side note Red Hat ships runtime configurable tick behavior in RHEL >these days. HZ is fixed but the ticks can be bunched up. That was done as >a quick fix to keep stuff portable but its a lot more sensible than >randomly messing with the HZ value and its not much code either. > That's interesting! Could you please point us to the patch if you can? (As a HPC + virtualization shop, we set HZ to 100 all the time, and a patch like the one you mention above sounds great) Thanks, Kiran