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 S1755626AbcGFTAM (ORCPT <rfc822;w@1wt.eu>);
	Wed, 6 Jul 2016 15:00:12 -0400
Received: from www.linutronix.de ([62.245.132.108]:41066 "EHLO
	Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1754068AbcGFTAK (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Wed, 6 Jul 2016 15:00:10 -0400
Date: Wed, 6 Jul 2016 20:57:59 +0200 (CEST)
From: Thomas Gleixner <tglx@linutronix.de>
To: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
cc: Darren Hart <dvhart@infradead.org>,
        Matthieu CASTET <matthieu.castet@parrot.com>,
        linux-kernel@vger.kernel.org, Darren Hart <dvhart@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Davidlohr Bueso <dave@stgolabs.net>,
        Eric Dumazet <dada1@cosmosbay.com>
Subject: Re: futex: Allow FUTEX_CLOCK_REALTIME with FUTEX_WAIT op
In-Reply-To: <f1dab560-41bb-9cc4-438f-0ade82c685fd@gmail.com>
Message-ID: <alpine.DEB.2.11.1607062055570.4083@nanos>
References: <20160620162652.2c4619c3@perruche.parrot.biz> <20160623044828.GA3379@f23x64.localdomain> <alpine.DEB.2.11.1606230913570.5839@nanos> <520d203a-83ad-0277-79d5-2209d6853628@gmail.com> <alpine.DEB.2.11.1606231534310.5839@nanos>
 <20160623161643.GA106079@f23x64.localdomain> <alpine.DEB.2.11.1606231925420.5839@nanos> <20160623182821.GB106079@f23x64.localdomain> <f1dab560-41bb-9cc4-438f-0ade82c685fd@gmail.com>
User-Agent: Alpine 2.11 (DEB 23 2013-08-11)
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
X-Linutronix-Spam-Score: -1.0
X-Linutronix-Spam-Level: -
X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required,  ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, 23 Jun 2016, Michael Kerrisk (man-pages) wrote:
> On 06/23/2016 08:28 PM, Darren Hart wrote:
> > And as a follow-on, what is the reason for FUTEX_LOCK_PI only using
> > CLOCK_REALTIME? It seems reasonable to me that a user may want to wait a
> > specific amount of time, regardless of wall time.
> 
> Yes, that's another weird inconsistency.

The reason is that phtread_mutex_timedlock() uses absolute timeouts based on
CLOCK_REALTIME. glibc folks asked to make that the default behaviour back then
when we added LOCK_PI.

Thanks,

	tglx