Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756036AbaGVQRT (ORCPT ); Tue, 22 Jul 2014 12:17:19 -0400 Received: from fw-tnat.austin.arm.com ([217.140.110.23]:47676 "EHLO collaborate-mta1.arm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755458AbaGVQRR (ORCPT ); Tue, 22 Jul 2014 12:17:17 -0400 Message-ID: <1406045831.25343.69.camel@hornet> Subject: Re: [RFC] sched_clock: Track monotonic raw clock From: Pawel Moll To: John Stultz Cc: Steven Rostedt , Ingo Molnar , Peter Zijlstra , Oleg Nesterov , Andrew Morton , Mel Gorman , Andy Lutomirski , Stephen Boyd , Baruch Siach , Thomas Gleixner , "linux-kernel@vger.kernel.org" Date: Tue, 22 Jul 2014 17:17:11 +0100 In-Reply-To: <53C95E97.2020805@linaro.org> References: <1405705419-4194-1-git-send-email-pawel.moll@arm.com> <53C95E97.2020805@linaro.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4-0ubuntu1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2014-07-18 at 18:51 +0100, John Stultz wrote: > Very cool work! Glad that it doesn't sound too ridiculous :-) > I've not been able to review it carefully, but one good > stress test would be to pick a system where the hardware used for > sched_clock is different from the hardware used for timekeeping. Actually I've got exactly this situation on my board. I've got two sources, and actually the worse (narrower and more expensive) one is getting eventually used (because it's registered later - separate patch to follow). > Although, looking again, this looks like it only works on the "generic" > sched_clock (so ARM/ARM64?)... ... and microblaze and xtensa right now, yes. This was just the simplest thing for me to start with, but I appreciate it doesn't cover all possible cases. Thus the debugfs attribute to tell userspace what can it expect from the sched_clock. A hack it is, yes. Pawel -- 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/