From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965551AbXCTSEj (ORCPT ); Tue, 20 Mar 2007 14:04:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751951AbXCTSEj (ORCPT ); Tue, 20 Mar 2007 14:04:39 -0400 Received: from gateway-1237.mvista.com ([63.81.120.158]:26346 "EHLO gateway-1237.mvista.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751948AbXCTSEi (ORCPT ); Tue, 20 Mar 2007 14:04:38 -0400 Subject: Re: [PATCH] time : SMP friendly alignment of struct clocksource From: Daniel Walker To: john stultz Cc: Eric Dumazet , Andrew Morton , linux kernel In-Reply-To: <1174413482.17430.1.camel@localhost> References: <20070320110936.1e445e6e.dada1@cosmosbay.com> <1174413482.17430.1.camel@localhost> Content-Type: text/plain Date: Tue, 20 Mar 2007 11:04:22 -0700 Message-Id: <1174413862.3101.185.camel@imap.mvista.com> Mime-Version: 1.0 X-Mailer: Evolution 2.8.2.1 (2.8.2.1-3.fc6) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2007-03-20 at 10:58 -0700, john stultz wrote: > > /* timekeeping specific data, ignore */ > > - cycle_t cycle_last, cycle_interval; > > - u64 xtime_nsec, xtime_interval; > > + cycle_t cycle_interval; > > + u64 xtime_interval; > > + /* > > + * Second part is written at each timer interrupt > > + * Keep it in a different cache line to dirty no > > + * more than one cache line. > > + */ > > + cycle_t cycle_last ____cacheline_aligned_in_smp; > > + u64 xtime_nsec; > > s64 error; What was the motivation for having these (cycle_last for example) in the clocksource structure. I recall them being added in there at one point, but I'm not sure why.. Specifically the ones that are updated often. Daniel