Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754788Ab0HBTtK (ORCPT ); Mon, 2 Aug 2010 15:49:10 -0400 Received: from hera.kernel.org ([140.211.167.34]:47157 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754628Ab0HBTtI (ORCPT ); Mon, 2 Aug 2010 15:49:08 -0400 Date: Mon, 2 Aug 2010 19:48:47 GMT From: tip-bot for Arjan van de Ven Cc: linux-kernel@vger.kernel.org, arjan@infradead.org, hpa@zytor.com, mingo@redhat.com, arjan@linux.intel.com, tglx@linutronix.de Reply-To: mingo@redhat.com, hpa@zytor.com, arjan@infradead.org, linux-kernel@vger.kernel.org, arjan@linux.intel.com, tglx@linutronix.de In-Reply-To: <20100727210210.58d3118c@infradead.org> References: <20100727210210.58d3118c@infradead.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:timers/core] clockevents: Remove the per cpu tick skew Message-ID: Git-Commit-ID: af5ab277ded04bd9bc6b048c5a2f0e7d70ef0867 X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Mon, 02 Aug 2010 19:48:48 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2012 Lines: 54 Commit-ID: af5ab277ded04bd9bc6b048c5a2f0e7d70ef0867 Gitweb: http://git.kernel.org/tip/af5ab277ded04bd9bc6b048c5a2f0e7d70ef0867 Author: Arjan van de Ven AuthorDate: Tue, 27 Jul 2010 21:02:10 -0700 Committer: Thomas Gleixner CommitDate: Mon, 2 Aug 2010 21:45:58 +0200 clockevents: Remove the per cpu tick skew Historically, Linux has tried to make the regular timer tick on the various CPUs not happen at the same time, to avoid contention on xtime_lock. Nowadays, with the tickless kernel, this contention no longer happens since time keeping and updating are done differently. In addition, this skew is actually hurting power consumption in a measurable way on many-core systems. Signed-off-by: Arjan van de Ven LKML-Reference: <20100727210210.58d3118c@infradead.org> Signed-off-by: Thomas Gleixner --- kernel/time/tick-sched.c | 5 ----- 1 files changed, 0 insertions(+), 5 deletions(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 813993b..74644cc 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -780,7 +780,6 @@ void tick_setup_sched_timer(void) { struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); ktime_t now = ktime_get(); - u64 offset; /* * Emulate tick processing via per-CPU hrtimers: @@ -790,10 +789,6 @@ void tick_setup_sched_timer(void) /* Get the next period (per cpu) */ hrtimer_set_expires(&ts->sched_timer, tick_init_jiffy_update()); - offset = ktime_to_ns(tick_period) >> 1; - do_div(offset, num_possible_cpus()); - offset *= smp_processor_id(); - hrtimer_add_expires_ns(&ts->sched_timer, offset); for (;;) { hrtimer_forward(&ts->sched_timer, now, tick_period); -- 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/