Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754871Ab3JBRP2 (ORCPT ); Wed, 2 Oct 2013 13:15:28 -0400 Received: from comal.ext.ti.com ([198.47.26.152]:48604 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754164Ab3JBRPY (ORCPT ); Wed, 2 Oct 2013 13:15:24 -0400 Message-ID: <524C5484.5000601@ti.com> Date: Wed, 2 Oct 2013 13:14:44 -0400 From: Santosh Shilimkar User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Will Deacon CC: "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "arm@kernel.org" , Stephen Boyd , John Stultz , Russell King , "rob.herring@calxeda.com" , Thomas Gleixner Subject: Re: [PATCH] sched_clock: fix postinit no sched_clock function check References: <1380732928-13897-1-git-send-email-santosh.shilimkar@ti.com> <20131002170917.GB30298@mudshark.cambridge.arm.com> In-Reply-To: <20131002170917.GB30298@mudshark.cambridge.arm.com> 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 Content-Length: 1449 Lines: 32 On Wednesday 02 October 2013 01:09 PM, Will Deacon wrote: > On Wed, Oct 02, 2013 at 05:55:28PM +0100, Santosh Shilimkar wrote: >> The sched_clock code uses 2 levels of function pointers, sched_clock_func() >> and read_sched_clock() but the no sched_clock check in postinit() just >> checks read_sched_clock(). >> >> This leads to kernel falling back to jiffy based sched clock even in >> presence of sched_clock_func() which is not desirable. >> >> Fix the postinit() check to avoid the issue. Probably the issue is hidden >> so far on most of the arm SOCs because of already existing sched_clock >> registrations apart from arch_timer sched_clock. One can reproduce the >> issue by just have arch_timer as sched_clock > > Isn't this just an issue with the arch timer driver not calling > setup_sched_clock? Instead, we munge around with sched_clock_func directly, > which doesn't appear to be the way anybody else deals with this. > I thought about that option as well but was not sure since even in that case the check is not complete. We just ensure that function is popullated. > I'm not sure of the history though, so perhaps there's a reason for this... > Am curious as well. Regards, Santosh -- 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/