Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762084AbaGRTqe (ORCPT ); Fri, 18 Jul 2014 15:46:34 -0400 Received: from mail-pd0-f179.google.com ([209.85.192.179]:41539 "EHLO mail-pd0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754906AbaGRTqd (ORCPT ); Fri, 18 Jul 2014 15:46:33 -0400 Message-ID: <53C97995.2090500@linaro.org> Date: Fri, 18 Jul 2014 12:46:29 -0700 From: John Stultz User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Peter Zijlstra CC: Pawel Moll , Steven Rostedt , Ingo Molnar , Oleg Nesterov , Andrew Morton , Mel Gorman , Andy Lutomirski , Stephen Boyd , Baruch Siach , Thomas Gleixner , lkml Subject: Re: [RFC] sched_clock: Track monotonic raw clock References: <1405705419-4194-1-git-send-email-pawel.moll@arm.com> <20140718191338.GF3935@laptop> <20140718193417.GG3935@laptop> In-Reply-To: <20140718193417.GG3935@laptop> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/18/2014 12:34 PM, Peter Zijlstra wrote: > On Fri, Jul 18, 2014 at 12:25:48PM -0700, John Stultz wrote: >> Also, assuming we someday will merge the x86 sched_clock logic into >> the generic sched_clock code, we'll have to handle cases where they >> aren't the same. > I prefer that to not happen. I spend quite a bit of time and effort to > make the x86 code go fast, and that generic code doesn't look like fast > at all. A stretch goal then :) But yes, the generic sched_clock logic has really just started w/ ARM and is hopefully moving out to pick up more architectures. I suspect it will need to adapt many of your tricks from (if not a whole migration to some of) the x86 code. And even if the x86 code stays separate for optimization reasons, thats fine. But as folks try to align things like perf timestamps with time domains we expose to userspace, we'll have to keep some of the semantics in sync between the various implementations, and having lots of separate implementations will be a burden. But yea, I don't have any plans to try to do a grand unification myself, so don't fret. thanks -john -- 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/