From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752740AbaAORja (ORCPT ); Wed, 15 Jan 2014 12:39:30 -0500 Received: from mx1.redhat.com ([209.132.183.28]:1463 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752719AbaAORjV (ORCPT ); Wed, 15 Jan 2014 12:39:21 -0500 Date: Wed, 15 Jan 2014 18:38:58 +0100 From: Oleg Nesterov To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, darren@dvhart.com, fweisbec@gmail.com, sbw@mit.edu Subject: Re: [PATCH tip/core/timers 2/4] timers: Reduce __run_timers() latency for empty list Message-ID: <20140115173858.GC14473@redhat.com> References: <20140115051939.GA31164@linux.vnet.ibm.com> <1389763248-31297-1-git-send-email-paulmck@linux.vnet.ibm.com> <1389763248-31297-2-git-send-email-paulmck@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1389763248-31297-2-git-send-email-paulmck@linux.vnet.ibm.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org forgot to mention... On 01/14, Paul E. McKenney wrote: > > +static bool catchup_timer_jiffies(struct tvec_base *base) > +{ > +#ifdef CONFIG_NO_HZ_FULL > + if (!base->all_timers) { > + base->timer_jiffies = jiffies; > + return 1; > + } > +#endif /* #ifdef CONFIG_NO_HZ_FULL */ > + return 0; > +} Do we really want ifdef? This check is cheap, and !CONFIG_NO_HZ_FULL case looks a bit strange because we still update ->all_timers for no reason. Oleg.