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 S1755677AbcIFNHt (ORCPT <rfc822;w@1wt.eu>);
        Tue, 6 Sep 2016 09:07:49 -0400
Received: from mail-wm0-f68.google.com ([74.125.82.68]:33447 "EHLO
        mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1753790AbcIFNHr (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Tue, 6 Sep 2016 09:07:47 -0400
Message-ID: <1473167264.32128.5.camel@gmail.com>
Subject: Re: [v2 patch v3.18+ regression fix] sched: Further improve
 spurious CPU_IDLE active migrations
From: Mike Galbraith <umgwanakikbuti@gmail.com>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
        LKML <linux-kernel@vger.kernel.org>, Rik van Riel <riel@redhat.com>
Date: Tue, 06 Sep 2016 15:07:44 +0200
In-Reply-To: <20160906130127.GA21960@vingu-laptop>
References: <1472535775.3960.3.camel@suse.de>
         <20160831100117.GV10121@twins.programming.kicks-ass.net>
         <1472638699.3942.14.camel@suse.de> <1472639782.3942.27.camel@gmail.com>
         <CAKfTPtDjrXnpVGat+avYrER7gKFurQLF_PB1Vt2Nu1dKy2o8aQ@mail.gmail.com>
         <1472703062.3979.60.camel@gmail.com>
         <CAKfTPtDxTH62HGrze+rSrw9+kZc6xHSfJemhWqxhyhLZzM0qDg@mail.gmail.com>
         <1473092813.4412.6.camel@gmail.com> <20160906130127.GA21960@vingu-laptop>
Content-Type: text/plain; charset="ISO-8859-1"
X-Mailer: Evolution 3.16.5 
Mime-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Tue, 2016-09-06 at 15:01 +0200, Vincent Guittot wrote:
> Le Monday 05 Sep 2016 à 18:26:53 (+0200), Mike Galbraith a écrit :
> > Coming back to this, how about this instead, only increase the group
> > imbalance threshold when sd_llc_size == 2.  Newer L3 equipped
> > processors then aren't affected.
> > 
> 
> Not sure that all systems with sd_llc_size == 2 wants this behavior.
> 
> Why not adding a sched_feature for changing the 2nd half of the test
> for some systems ?

Because users won't know, and shouldn't need to know that they need to
flip that switch.

	-Mike