From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Rostedt Subject: Re: [RFC patch] introduce sys_membarrier(): process-wide memory barrier (v9) Date: Thu, 25 Feb 2010 13:08:51 -0500 Message-ID: <1267121331.6328.30.camel@gandalf.stny.rr.com> References: <20100212224606.GA30280@Krystal> <4B82CF1A.3010501@nortel.com> <20100222212321.GA2573@Krystal> <20100224091052.GY9738@laptop> <20100224152251.GA16295@Krystal> <20100225053310.GA9738@laptop> <20100225165301.GF24052@Krystal> <1267118726.6328.20.camel@gandalf.stny.rr.com> <20100225175121.GA6658@Krystal> Reply-To: rostedt@goodmis.org Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-15" Content-Transfer-Encoding: 7bit Return-path: Received: from hrndva-omtalb.mail.rr.com ([71.74.56.123]:54968 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933195Ab0BYSI7 (ORCPT ); Thu, 25 Feb 2010 13:08:59 -0500 In-Reply-To: <20100225175121.GA6658@Krystal> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Mathieu Desnoyers Cc: Nick Piggin , Chris Friesen , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, KOSAKI Motohiro , "Paul E. McKenney" , Nicholas Miell , Linus Torvalds , mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, josh@joshtriplett.org, dvhltc@us.ibm.com, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com On Thu, 2010-02-25 at 12:51 -0500, Mathieu Desnoyers wrote: > But... either way we chose, we can extend the system call flags and parameters > as needed, so I think it really should not be part of this initial > implementation. I agree here too. If you have two different tasks doing lockless RCU or what not on shared memory, it's best to stick with the mb() on the reader side. Yeah, it makes the performance go down, but heck, I'm really worried about the crazy complexity that wound need to go into the kernel to prevent this. -- Steve