Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759239Ab3GSO1i (ORCPT ); Fri, 19 Jul 2013 10:27:38 -0400 Received: from caramon.arm.linux.org.uk ([78.32.30.218]:37628 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751509Ab3GSO1h (ORCPT ); Fri, 19 Jul 2013 10:27:37 -0400 Date: Fri, 19 Jul 2013 15:27:18 +0100 From: Russell King - ARM Linux To: Nicolas Pitre Cc: Will Deacon , Stephen Boyd , John Stultz , "linux-kernel@vger.kernel.org" , "linux-arm-msm@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Thomas Gleixner , Catalin Marinas , Christopher Covington Subject: Re: [PATCH v4 02/17] sched_clock: Use seqcount instead of rolling our own Message-ID: <20130719142718.GG24642@n2100.arm.linux.org.uk> References: <1374189690-10810-1-git-send-email-sboyd@codeaurora.org> <1374189690-10810-3-git-send-email-sboyd@codeaurora.org> <20130719090328.GA18139@mudshark.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 792 Lines: 18 On Fri, Jul 19, 2013 at 10:20:19AM -0400, Nicolas Pitre wrote: > On Fri, 19 Jul 2013, Will Deacon wrote: > > > Looks good to me. The current scheme would be very fiddly to extend to > > 64-bit values on 32-bit architectures without cheap atomic doubleword > > accesses. > > You should have a look at include/linux/cnt32_to_63.h. > This could be applied to pure software counters if the low part is > atomically increased. But this can't be used for sched_clock(). That's exactly why I originally had to rewrite that thing in the first place. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/