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 S1754838AbbCQRap (ORCPT <rfc822;w@1wt.eu>);
	Tue, 17 Mar 2015 13:30:45 -0400
Received: from casper.infradead.org ([85.118.1.10]:50002 "EHLO
	casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1754173AbbCQRan (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Tue, 17 Mar 2015 13:30:43 -0400
Date: Tue, 17 Mar 2015 18:30:35 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: linux-kernel@vger.kernel.org,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Josh Triplett <josh@joshtriplett.org>,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Nicholas Miell <nmiell@comcast.net>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Ingo Molnar <mingo@redhat.com>, Alan Cox <gnomes@lxorguk.ukuu.org.uk>,
        Lai Jiangshan <laijs@cn.fujitsu.com>,
        Stephen Hemminger <stephen@networkplumber.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        David Howells <dhowells@redhat.com>
Subject: Re: [RFC PATCH v13] sys_membarrier(): system/process-wide memory
 barrier (x86)
Message-ID: <20150317173035.GI23123@twins.programming.kicks-ass.net>
References: <1426612922-3308-1-git-send-email-mathieu.desnoyers@efficios.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1426612922-3308-1-git-send-email-mathieu.desnoyers@efficios.com>
User-Agent: Mutt/1.5.21 (2012-12-30)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Tue, Mar 17, 2015 at 01:22:02PM -0400, Mathieu Desnoyers wrote:
> Here is an implementation of a new system call, sys_membarrier(), which
> executes a memory barrier on either all running threads of the current
> process (MEMBARRIER_PRIVATE) issues a memory barrier on all threads
> running on the system (~MEMBARRIER_PRIVATE). Both are currently
> implemented by calling synchronize_sched().

Then why bother with the flag?