From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936361AbYEBWH7 (ORCPT ); Fri, 2 May 2008 18:07:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965015AbYEBWHr (ORCPT ); Fri, 2 May 2008 18:07:47 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:51352 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965016AbYEBWHq (ORCPT ); Fri, 2 May 2008 18:07:46 -0400 Subject: Re: 'global' rq->clock From: Peter Zijlstra To: David Miller Cc: efault@gmx.de, elendil@planet.nl, parag.warudkar@gmail.com, mingo@elte.hu, linux-kernel@vger.kernel.org, guichaz@yahoo.fr, andi@firstfloor.org In-Reply-To: <20080502.144827.158329188.davem@davemloft.net> References: <200805022053.24779.elendil@planet.nl> <1209756423.4693.8.camel@marge.simson.net> <1209758186.6929.18.camel@lappy> <20080502.144827.158329188.davem@davemloft.net> Content-Type: text/plain Date: Sat, 03 May 2008 00:07:34 +0200 Message-Id: <1209766054.6929.29.camel@lappy> Mime-Version: 1.0 X-Mailer: Evolution 2.22.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2008-05-02 at 14:48 -0700, David Miller wrote: > From: Peter Zijlstra > Date: Fri, 02 May 2008 21:56:26 +0200 > > > Ok, the the below would need something that relates tick_timestamp's to > > one another.. probably sucks without it.. > > > > OTOH, Andi said he was working on a fastish global sched_clock() thingy, > > Andi got a link to that code? > > While I'm fine with this kind of stuff being added to constantly cope > with x86's joke of a TSC register implementation, it's starting to > become an enormous burdon for platforms where the TICK source actually > works properly. > > Heck, on my Niagara2 chips, all 64 cpus use the same physical register > for the TICK source, it physically can't get desynchronized :-) > > So, a way to turn all of this muck off would be much appreciated. > I'm happy to test anything on sparc64, and I'm sure the powerpc > folks are as well. > > And I also heard a rumor that Peter has access to a machine with a > stable tick source for testing :-) Yeah, I was thinking of a way for architectures to signify how much help they need building the various clocks. Sparc, power and s390 would not need any help.