Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752202Ab3F0JzC (ORCPT ); Thu, 27 Jun 2013 05:55:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44404 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750806Ab3F0JzA (ORCPT ); Thu, 27 Jun 2013 05:55:00 -0400 Message-ID: <51CC0BC3.5090309@redhat.com> Date: Thu, 27 Jun 2013 11:54:11 +0200 From: Hans de Goede User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130612 Thunderbird/17.0.6 MIME-Version: 1.0 To: Maxime Ripard CC: linux-sunxi@googlegroups.com, John Stultz , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Emilio Lopez , kevin@allwinnertech.com, sunny@allwinnertech.com, shuge@allwinnertech.com Subject: Re: [linux-sunxi] [PATCH 0/8] clocksource: sunxi: Timer fixes and cleanup References: <1372281421-2099-1-git-send-email-maxime.ripard@free-electrons.com> <51CC0566.8010302@redhat.com> <20130627094307.GC8437@lukather> In-Reply-To: <20130627094307.GC8437@lukather> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1525 Lines: 52 Hi, On 06/27/2013 11:43 AM, Maxime Ripard wrote: > On Thu, Jun 27, 2013 at 11:27:02AM +0200, Hans de Goede wrote: >> Hi, >> >> On 06/26/2013 11:16 PM, Maxime Ripard wrote: >>> Hi everyone, >>> >> >> >> >>> It also finally adds a clocksource from the free running counter found in the >>> A10/A13 SoCs. >> >> Hmm, have you benchmarked this? There have been reports from linux-sunxi kernel >> users (xbmc project) that the waiting for the latch is quite slow. Note we >> don't have anything better yet in the linux-sunxi kernel. > > No. I didn't. > > Do you have any pointers to these discussions? > The original discussion should be somewhere here: https://groups.google.com/forum/#!forum/linux-sunxi But I could not find it (it is probably hidden under an unlogical subject). Looking at my own notes (a small TODO file), I've written down that the reporter reports: -current clocksource can cause us to run with interrupts disabled for 17% of the time, see "perf top" output This is with a workload which does a lot of gettimeofday calls. I notice that unlike the sunxi-3.4 code you don't do any locking, so how do you stop 2 clocksource calls from racing (and thus getting a possible wrong value because of things not being properly latched) ? Regards, Hans -- 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/