From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1756712AbcASQtn (ORCPT <rfc822;w@1wt.eu>);
	Tue, 19 Jan 2016 11:49:43 -0500
Received: from mail-wm0-f65.google.com ([74.125.82.65]:36165 "EHLO
	mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1756594AbcASQth (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Tue, 19 Jan 2016 11:49:37 -0500
Date: Tue, 19 Jan 2016 17:49:34 +0100
From: Frederic Weisbecker <fweisbec@gmail.com>
To: Byungchul Park <byungchul.park@lge.com>
Cc: Peter Zijlstra <peterz@infradead.org>, LKML <linux-kernel@vger.kernel.org>,
        Chris Metcalf <cmetcalf@ezchip.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Luiz Capitulino <lcapitulino@redhat.com>,
        Christoph Lameter <cl@linux.com>,
        "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
        Mike Galbraith <efault@gmx.de>, Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH 2/4] sched: Consolidate nohz CPU load update code
Message-ID: <20160119164933.GB5317@lerouge>
References: <1452700891-21807-1-git-send-email-fweisbec@gmail.com>
 <1452700891-21807-3-git-send-email-fweisbec@gmail.com>
 <20160114051840.GA4224@X58A-UD3R>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20160114051840.GA4224@X58A-UD3R>
User-Agent: Mutt/1.5.24 (2015-08-30)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, Jan 14, 2016 at 02:18:40PM +0900, Byungchul Park wrote:
> On Wed, Jan 13, 2016 at 05:01:29PM +0100, Frederic Weisbecker wrote:
> >  #ifdef CONFIG_NO_HZ_COMMON
> > +static void __update_cpu_load_nohz(struct rq *this_rq,
> > +				   unsigned long curr_jiffies,
> 
> Do we need to pass current jiffies as a function parameter?

I guess we don't, I just wasn't much sure of the possible overhead of READ_ONCE()

> 
> > +				   unsigned long load,
> > +				   int active)
> > +{
> > +	unsigned long pending_updates;
> > +
> > +	pending_updates = curr_jiffies - this_rq->last_load_update_tick;
> > +	if (pending_updates) {
> > +		this_rq->last_load_update_tick = curr_jiffies;
> > +		/*
> > +		 * In the regular NOHZ case, we were idle, this means load 0.
> > +		 * In the NOHZ_FULL case, we were non-idle, we should consider
> > +		 * its weighted load.
> > +		 */
> > +		__update_cpu_load(this_rq, load, pending_updates, active);
> > +	}
> > +}