From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5977FC4724C for ; Thu, 30 Apr 2020 17:33:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 36B05208D6 for ; Thu, 30 Apr 2020 17:33:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588268032; bh=7OyWguI2rc8GY3pA0j9peooBQlK7C47Glh0LtwePdIk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=LKcm89iQIP6Z1LAIRvVaG/u4gXEO8o6x+R9BzUZXV5RUi8ODKsAXYIx3B9JEhpNBb 3aJMznvGC62vfHpuBQPU93iCBn+YJokIyXEANwGwtBC9vo+tlhml7JPkNyjP4Lnyfr M4FbM6RTyZmo1CxgaUKKuZFuRs6cvrKKIXjCcrBY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726545AbgD3Rdv (ORCPT ); Thu, 30 Apr 2020 13:33:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:59786 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726285AbgD3Rdv (ORCPT ); Thu, 30 Apr 2020 13:33:51 -0400 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5073420731; Thu, 30 Apr 2020 17:33:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588268030; bh=7OyWguI2rc8GY3pA0j9peooBQlK7C47Glh0LtwePdIk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=uZQ0OiesVFY93yX2EfPV0iDC0FtwkI9adRQbqtcv9aFNMXPHmIlaCF/kJGAX1TUIj AFklv3y61RLexW0fOo3TbXxWPuLsoNpc/HsHCj45LEZHK5ssnvfyHEVi/0oWa3vLk1 KT29VYG7slez9Z2zJI4CTxEsaC9TugxUPaI135NM= Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1jUD4G-0088DI-K4; Thu, 30 Apr 2020 18:33:48 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Thu, 30 Apr 2020 18:33:48 +0100 From: Marc Zyngier To: Will Deacon Cc: Peter Zijlstra , Leo Yan , Mark Rutland , Ingo Molnar , Arnaldo Carvalho de Melo , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Catalin Marinas , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Mathieu Poirier , Mike Leach , Al Grant , James Clark , tglx@linutronix.de Subject: Re: [PATCH] arm64: perf_event: Fix time_offset for arch timer In-Reply-To: <20200430161815.GE25258@willie-the-truck> References: <20200320093545.28227-1-leo.yan@linaro.org> <20200430145823.GA25258@willie-the-truck> <4d924f705245c797a19d3a73eb0c1ba0@kernel.org> <20200430160436.GC13575@hirez.programming.kicks-ass.net> <20200430161815.GE25258@willie-the-truck> User-Agent: Roundcube Webmail/1.4.3 Message-ID: <79ba3f5f9af951b2de52b8eb9e1bc25f@kernel.org> X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: will@kernel.org, peterz@infradead.org, leo.yan@linaro.org, mark.rutland@arm.com, mingo@redhat.com, acme@kernel.org, alexander.shishkin@linux.intel.com, jolsa@redhat.com, namhyung@kernel.org, catalin.marinas@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, mathieu.poirier@linaro.org, mike.leach@linaro.org, Al.Grant@arm.com, James.Clark@arm.com, tglx@linutronix.de X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-04-30 17:18, Will Deacon wrote: > On Thu, Apr 30, 2020 at 06:04:36PM +0200, Peter Zijlstra wrote: >> On Thu, Apr 30, 2020 at 04:29:23PM +0100, Marc Zyngier wrote: >> >> > I wonder if we could/should make __sched_clock_offset available even when >> > CONFIG_HAVE_UNSTABLE_SCHED_CLOCK isn't defined. It feels like it would >> > help with this particular can or worm... >> >> Errrgh. __sched_clock_offset is only needed on x86 because we >> transition >> from one clock device to another on boot. It really shouldn't exist on >> anything sane. > > I think we still transition from jiffies on arm64, because we don't > register > with sched_clock until the timer driver probes. Marc, is that right? Indeed. The clocksource is only available relatively late, as we need to discover the details of the platform and enable the various workarounds (because nobody can get a simple 64bit counter right). So it is only at that stage that we transition to it. M. -- Jazz is not dead. It just smells funny...