Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757457Ab3J1U7M (ORCPT ); Mon, 28 Oct 2013 16:59:12 -0400 Received: from e06smtp12.uk.ibm.com ([195.75.94.108]:55896 "EHLO e06smtp12.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756885Ab3J1U7K (ORCPT ); Mon, 28 Oct 2013 16:59:10 -0400 In-Reply-To: <20131028201735.GA15629@redhat.com> References: <12083.1382486094@ale.ozlabs.ibm.com> <20131023141948.GB3566@localhost.localdomain> <20131025173749.GG19466@laptop.lan> <20131028132634.GO19466@laptop.lan> <20131028163418.GD4126@linux.vnet.ibm.com> <20131028201735.GA15629@redhat.com> Subject: Re: perf events ring buffer memory barrier on powerpc X-KeepSent: 58D85F5A:03E37A80-42257C12:0070E552; type=4; name=$KeepSent To: Oleg Nesterov Cc: Anton Blanchard , Benjamin Herrenschmidt , Frederic Weisbecker , LKML , Linux PPC dev , Mathieu Desnoyers , Michael Ellerman , Michael Neuling , "Paul E. McKenney" , Peter Zijlstra X-Mailer: Lotus Notes Release 8.5.3 September 15, 2011 Message-ID: From: Victor Kaplansky Date: Mon, 28 Oct 2013 22:58:58 +0200 X-MIMETrack: Serialize by Router on D06ML319/06/M/IBM(Release 8.5.3FP5|July 31, 2013) at 28/10/2013 22:58:51 MIME-Version: 1.0 Content-type: text/plain; charset=US-ASCII X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13102820-8372-0000-0000-00000799794E Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 576 Lines: 15 Oleg Nesterov wrote on 10/28/2013 10:17:35 PM: > mb(); // XXXXXXXX: do we really need it? I think yes. Oh, it is hard to argue with feelings. Also, it is easy to be on conservative side and put the barrier here just in case. But I still insist that the barrier is redundant in your example. -- Victor -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/