From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030297AbbCMPQY (ORCPT ); Fri, 13 Mar 2015 11:16:24 -0400 Received: from smtprelay0132.hostedemail.com ([216.40.44.132]:34862 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932203AbbCMPPX (ORCPT ); Fri, 13 Mar 2015 11:15:23 -0400 X-Session-Marker: 6E657665747340676F6F646D69732E6F7267 X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,,::::::::::::::::::::::::,RULES_HIT:355:379:871:988:989:1183:1260:1277:1312:1313:1314:1345:1516:1518:1519:1522:1534:1593:1594:1595:1596:1692:1730:1747:1777:1792:2392:2393:2559:2562:2828:3138:3139:3140:3141:3142:3876:3877:5007:6114:6261:6642:6748:7281:7901:9012:10004:10848:11604:11914:12517:12519:13255:13895:14394:21080,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0 X-HE-Tag: store17_68e9dac089e1a X-Filterd-Recvd-Size: 3077 Message-Id: <20150313151520.061444744@goodmis.org> User-Agent: quilt/0.61-1 Date: Fri, 13 Mar 2015 11:15:24 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-rt-users Cc: Thomas Gleixner , Carsten Emde , Sebastian Andrzej Siewior , John Kacur , Paul Gortmaker , "Paul E. McKenney" , Josh Triplett , Peter Zijlstra , Oleg Nesterov , Mike Galbraith Subject: [PATCH RT 30/31] timers: Reduce future __run_timers() latency for first add to empty list References: <20150313151454.809081378@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Disposition: inline; filename=0030-timers-Reduce-future-__run_timers-latency-for-first-.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.10.70-rt75-rc1 stable review patch. If anyone has any objections, please let me know. ------------------ From: "Paul E. McKenney" upstream commit: 18d8cb64c9c074cbe2bd677ab10fff8283abdb62 The __run_timers() function currently steps through the list one jiffy at a time in order to update the timer wheel. However, if the timer wheel is empty, no adjustment is needed other than updating ->timer_jiffies. Therefore, just before we add a timer to an empty timer wheel, we should mark the timer wheel as being up to date. This marking will reduce (and perhaps eliminate) the jiffy-stepping that a future __run_timers() call will need to do in response to some future timer posting or migration. This commit therefore updates ->timer_jiffies for this case. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett Acked-by: Peter Zijlstra Reviewed-by: Oleg Nesterov Reviewed-by: Steven Rostedt Tested-by: Mike Galbraith Signed-off-by: Steven Rostedt --- kernel/timer.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/timer.c b/kernel/timer.c index 39f5caef6714..06050920aee5 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -401,6 +401,7 @@ __internal_add_timer(struct tvec_base *base, struct timer_list *timer) static void internal_add_timer(struct tvec_base *base, struct timer_list *timer) { + (void)catchup_timer_jiffies(base); __internal_add_timer(base, timer); /* * Update base->active_timers and base->next_timer -- 2.1.4