From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756335AbbCGCwf (ORCPT ); Fri, 6 Mar 2015 21:52:35 -0500 Received: from mail-pd0-f177.google.com ([209.85.192.177]:40232 "EHLO mail-pd0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755059AbbCGCud (ORCPT ); Fri, 6 Mar 2015 21:50:33 -0500 From: John Stultz To: lkml Cc: John Stultz Subject: [PATCH 09/12] clocksource: Improve clocksource watchdog reporting Date: Fri, 6 Mar 2015 18:50:00 -0800 Message-Id: <1425696603-16878-10-git-send-email-john.stultz@linaro.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1425696603-16878-1-git-send-email-john.stultz@linaro.org> References: <1425696603-16878-1-git-send-email-john.stultz@linaro.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The clocksource watchdog reporting has been less helpful then desired, as it just printed the delta between the two clocksources. This prevents any useful analysis of why the skew occurred. Thus this patch tries to improve the output when we mark a clocksource as unstable, printing out the cycle last and now values for both the current clocksource and the watchdog clocksource. This will allow us to see if the result was due to a false positive caused by a problematic watchdog. Signed-off-by: John Stultz --- kernel/time/clocksource.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index e6c752b..51c7b3a 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -142,13 +142,6 @@ static void __clocksource_unstable(struct clocksource *cs) schedule_work(&watchdog_work); } -static void clocksource_unstable(struct clocksource *cs, int64_t delta) -{ - printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)\n", - cs->name, delta); - __clocksource_unstable(cs); -} - /** * clocksource_mark_unstable - mark clocksource unstable via watchdog * @cs: clocksource to be marked unstable @@ -174,7 +167,7 @@ void clocksource_mark_unstable(struct clocksource *cs) static void clocksource_watchdog(unsigned long data) { struct clocksource *cs; - cycle_t csnow, wdnow, delta; + cycle_t csnow, wdnow, cslast, wdlast, delta; int64_t wd_nsec, cs_nsec; int next_cpu, reset_pending; @@ -213,6 +206,8 @@ static void clocksource_watchdog(unsigned long data) delta = clocksource_delta(csnow, cs->cs_last, cs->mask); cs_nsec = clocksource_cyc2ns(delta, cs->mult, cs->shift); + wdlast = cs->wd_last; /* save these incase we print them */ + cslast = cs->cs_last; cs->cs_last = csnow; cs->wd_last = wdnow; @@ -221,7 +216,15 @@ static void clocksource_watchdog(unsigned long data) /* Check the deviation from the watchdog clocksource. */ if ((abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD)) { - clocksource_unstable(cs, cs_nsec - wd_nsec); + pr_warn("Watchdog: clocksource %s unstable\n", + cs->name); + pr_warn(" " + "%s wd_now: %llx wd_last: %llx mask: %llx\n", + watchdog->name, wdnow, wdlast, watchdog->mask); + pr_warn(" " + "%s cs_now: %llx cs_last: %llx mask: %llx\n", + cs->name, csnow, cslast, cs->mask); + __clocksource_unstable(cs); continue; } -- 1.9.1