From patchwork Wed Mar 4 18:27:53 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tony Lindgren X-Patchwork-Id: 9885 X-Patchwork-Delegate: tony@atomide.com Received: from vger.kernel.org (vger.kernel.org [209.132.176.167]) by demeter.kernel.org (8.14.2/8.14.2) with ESMTP id n24IRwuZ017924 for ; Wed, 4 Mar 2009 18:27:58 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753421AbZCDS16 (ORCPT ); Wed, 4 Mar 2009 13:27:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753582AbZCDS15 (ORCPT ); Wed, 4 Mar 2009 13:27:57 -0500 Received: from mho-01-bos.mailhop.org ([63.208.196.178]:65058 "EHLO mho-01-bos.mailhop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753421AbZCDS15 (ORCPT ); Wed, 4 Mar 2009 13:27:57 -0500 Received: from c-69-181-40-92.hsd1.ca.comcast.net ([69.181.40.92] helo=[127.0.0.1]) by mho-01-bos.mailhop.org with esmtpa (Exim 4.68) (envelope-from ) id 1Levow-000LeT-FS; Wed, 04 Mar 2009 18:27:55 +0000 X-Mail-Handler: MailHop Outbound by DynDNS X-Originating-IP: 69.181.40.92 X-Report-Abuse-To: abuse@dyndns.com (see http://www.dyndns.com/services/mailhop/outbound_abuse.html for abuse reporting information) X-MHO-User: U2FsdGVkX1/XFYts7scNs5u8CHUOxdKK Subject: [PATCH 2/4] ARM: OMAP: sched_clock() corrected To: linux-arm-kernel@lists.arm.linux.org.uk From: Tony Lindgren Cc: linux-omap@vger.kernel.org, Aaro Koskinen Date: Wed, 04 Mar 2009 10:27:53 -0800 Message-ID: <20090304182753.27331.99951.stgit@localhost> In-Reply-To: <20090304182342.27331.35004.stgit@localhost> References: <20090304182342.27331.35004.stgit@localhost> User-Agent: StGit/0.14.3.343.g0584 MIME-Version: 1.0 Sender: linux-omap-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org From: Aaro Koskinen After my OMAP3 board has been running for a while, I'm seeing weird latency traces like this: sh-1574 0d.h2 153us : do_timer (tick_do_update_jiffies64) sh-1574 0d.h2 153us : update_wall_time (do_timer) sh-1574 0d.h2 153us!: omap_32k_read (update_wall_time) sh-1574 0d.h2 1883us : update_xtime_cache (update_wall_time) sh-1574 0d.h2 1883us : clocksource_get_next (update_wall_time) sh-1574 0d.h2 1883us+: _spin_lock_irqsave (clocksource_get_next) and after a while: sh-17818 0d.h3 153us : do_timer (tick_do_update_jiffies64) sh-17818 0d.h3 153us : update_wall_time (do_timer) sh-17818 0d.h3 153us!: omap_32k_read (update_wall_time) sh-17818 0d.h3 1915us : update_xtime_cache (update_wall_time) sh-17818 0d.h3 1915us+: clocksource_get_next (update_wall_time) sh-17818 0d.h3 1945us : _spin_lock_irqsave (clocksource_get_next) Turns out that sched_clock() is using cyc2ns(), which returns NTP adjusted time. The sched_clock() frequency should not be adjusted. The patch deletes omap_32k_ticks_to_nsecs() and rewrites sched_clock() to do the conversion using the constant multiplier. Signed-off-by: Aaro Koskinen Signed-off-by: Tony Lindgren --- arch/arm/plat-omap/common.c | 14 +++++--------- 1 files changed, 5 insertions(+), 9 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/arch/arm/plat-omap/common.c b/arch/arm/plat-omap/common.c index 0843b88..6825fbb 100644 --- a/arch/arm/plat-omap/common.c +++ b/arch/arm/plat-omap/common.c @@ -200,20 +200,16 @@ static struct clocksource clocksource_32k = { }; /* - * Rounds down to nearest nsec. - */ -unsigned long long omap_32k_ticks_to_nsecs(unsigned long ticks_32k) -{ - return cyc2ns(&clocksource_32k, ticks_32k); -} - -/* * Returns current time from boot in nsecs. It's OK for this to wrap * around for now, as it's just a relative time stamp. */ unsigned long long sched_clock(void) { - return omap_32k_ticks_to_nsecs(omap_32k_read()); + unsigned long long ret; + + ret = (unsigned long long)omap_32k_read(); + ret = (ret * clocksource_32k.mult_orig) >> clocksource_32k.shift; + return ret; } static int __init omap_init_clocksource_32k(void)