From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758617Ab2HVIxl (ORCPT ); Wed, 22 Aug 2012 04:53:41 -0400 Received: from terminus.zytor.com ([198.137.202.10]:40067 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753275Ab2HVIxd (ORCPT ); Wed, 22 Aug 2012 04:53:33 -0400 Date: Wed, 22 Aug 2012 01:52:59 -0700 From: tip-bot for John Stultz Message-ID: Cc: linux-kernel@vger.kernel.org, john.stultz@linaro.org, hpa@zytor.com, mingo@kernel.org, tglx@linutronix.de, prarit@redhat.com Reply-To: mingo@kernel.org, hpa@zytor.com, john.stultz@linaro.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, prarit@redhat.com In-Reply-To: <1345595449-34965-5-git-send-email-john.stultz@linaro.org> References: <1345595449-34965-5-git-send-email-john.stultz@linaro.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:timers/urgent] time: Avoid making adjustments if we haven' t accumulated anything Git-Commit-ID: bf2ac312195155511a0f79325515cbb61929898a X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.6 (terminus.zytor.com [127.0.0.1]); Wed, 22 Aug 2012 01:53:09 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: bf2ac312195155511a0f79325515cbb61929898a Gitweb: http://git.kernel.org/tip/bf2ac312195155511a0f79325515cbb61929898a Author: John Stultz AuthorDate: Tue, 21 Aug 2012 20:30:49 -0400 Committer: Thomas Gleixner CommitDate: Wed, 22 Aug 2012 10:42:13 +0200 time: Avoid making adjustments if we haven't accumulated anything If update_wall_time() is called and the current offset isn't large enough to accumulate, avoid re-calling timekeeping_adjust which may change the clock freq and can cause 1ns inconsistencies with CLOCK_REALTIME_COARSE/CLOCK_MONOTONIC_COARSE. Signed-off-by: John Stultz Cc: Prarit Bhargava Cc: Ingo Molnar Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1345595449-34965-5-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner --- kernel/time/timekeeping.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index a5a9389..0c1485e 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1152,6 +1152,10 @@ static void update_wall_time(void) offset = (clock->read(clock) - clock->cycle_last) & clock->mask; #endif + /* Check if there's really nothing to do */ + if (offset < tk->cycle_interval) + goto out; + /* * With NO_HZ we may have to accumulate many cycle_intervals * (think "ticks") worth of time at once. To do this efficiently,