Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752170AbbEAIRU (ORCPT ); Fri, 1 May 2015 04:17:20 -0400 Received: from smtp4-g21.free.fr ([212.27.42.4]:27615 "EHLO smtp4-g21.free.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750786AbbEAIRQ (ORCPT ); Fri, 1 May 2015 04:17:16 -0400 Message-ID: <5543367E.5040807@free.fr> Date: Fri, 01 May 2015 10:17:02 +0200 From: Mason User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:36.0) Gecko/20100101 Firefox/36.0 SeaMonkey/2.33.1 MIME-Version: 1.0 To: John Stultz CC: LKML , Thomas Gleixner , Catalin Marinas Subject: Re: High-resolution timers not supported when using smp_twd References: <55422441.4040802@free.fr> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1085 Lines: 35 Hello John, On 30/04/2015 18:42, John Stultz wrote: > On Thu, Apr 30, 2015 at 5:46 AM, Mason wrote: > >> I wanted to enable high-resolution timers on this Cortex A9 system, >> but it seems there is more to it than just enabling >> >> CONFIG_HIGH_RES_TIMERS=y >> >> (The system is limited to jiffy resolution.) > > You might make sure you've got a HRT enabled clocksource installed? > > You might check > /sys/devices/system/clocksource/clocksource0/current_clocksource ? Thanks for the suggestion, I will check on Monday. The clocksource is a constant 27 MHz 32-bit counter. It seems the problem comes from the clockevent source, which is marked CLOCK_EVT_FEAT_C3STOP. If I remove that flag, then hrtimers are enabled; but the flag is there for a good reason, I assume. I will resend my message to the LAKML on Monday. Regards. -- 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/