Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756608AbaDQKJY (ORCPT ); Thu, 17 Apr 2014 06:09:24 -0400 Received: from merlin.infradead.org ([205.233.59.134]:57830 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751454AbaDQKJU (ORCPT ); Thu, 17 Apr 2014 06:09:20 -0400 Date: Thu, 17 Apr 2014 12:09:06 +0200 From: Peter Zijlstra To: Hidetoshi Seto Cc: linux-kernel@vger.kernel.org, Fernando Luis Vazquez Cao , Tetsuo Handa , Frederic Weisbecker , Thomas Gleixner , Ingo Molnar , Andrew Morton , Arjan van de Ven , Oleg Nesterov , Preeti U Murthy , Denys Vlasenko , stable@vger.kernel.org Subject: Re: [PATCH 2/2] nohz: use delayed iowait accounting to avoid race on idle time stats Message-ID: <20140417100906.GP13658@twins.programming.kicks-ass.net> References: <53465F54.708@jp.fujitsu.com> <534660D2.1080505@jp.fujitsu.com> <20140415101910.GN11096@twins.programming.kicks-ass.net> <534E2422.1040706@jp.fujitsu.com> <20140417100519.GF11096@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140417100519.GF11096@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 17, 2014 at 12:05:19PM +0200, Peter Zijlstra wrote: > +static inline void iowait_start(struct rq *rq) > +{ > + raw_spin_lock(&rq->iowait_lock); > + rq->nr_iowait++; > + raw_spin_unlock(&rq->iowait_lock); > + current->in_iowait = 1; > +} > + > +static inline void iowait_stop(struct rq *rq) > +{ > + current->in_iowait = 0; > + raw_spin_lock(&rq->iowait_lock); > + rq->nr_iowait--; > + if (!rq->nr_iowait && rq != this_rq()) > + rq->last_iowait = ktime_get(); > + raw_spin_unlock(&rq->iowait_lock); > +} We could actually use lockref here... -- 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/