From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 73DF0C433FF for ; Tue, 30 Jul 2019 15:59:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 45F3A208E4 for ; Tue, 30 Jul 2019 15:59:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732762AbfG3P7g (ORCPT ); Tue, 30 Jul 2019 11:59:36 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:49982 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728825AbfG3P7b (ORCPT ); Tue, 30 Jul 2019 11:59:31 -0400 Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x6UFvctd054436; Tue, 30 Jul 2019 11:59:15 -0400 Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 2u2q8mdfh9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 30 Jul 2019 11:59:14 -0400 Received: from m0098417.ppops.net (m0098417.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.27/8.16.0.27) with SMTP id x6UFvxeT055565; Tue, 30 Jul 2019 11:59:05 -0400 Received: from ppma04dal.us.ibm.com (7a.29.35a9.ip4.static.sl-reverse.com [169.53.41.122]) by mx0a-001b2d01.pphosted.com with ESMTP id 2u2q8mdf2f-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 30 Jul 2019 11:59:05 -0400 Received: from pps.filterd (ppma04dal.us.ibm.com [127.0.0.1]) by ppma04dal.us.ibm.com (8.16.0.27/8.16.0.27) with SMTP id x6UFtFgj004690; Tue, 30 Jul 2019 15:58:48 GMT Received: from b01cxnp23034.gho.pok.ibm.com (b01cxnp23034.gho.pok.ibm.com [9.57.198.29]) by ppma04dal.us.ibm.com with ESMTP id 2u0e86qs7c-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 30 Jul 2019 15:58:48 +0000 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp23034.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x6UFwlNw36503878 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 30 Jul 2019 15:58:47 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7357AB2065; Tue, 30 Jul 2019 15:58:47 +0000 (GMT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5089BB2064; Tue, 30 Jul 2019 15:58:47 +0000 (GMT) Received: from paulmck-ThinkPad-W541 (unknown [9.85.181.16]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Tue, 30 Jul 2019 15:58:47 +0000 (GMT) Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id E976416C13A3; Tue, 30 Jul 2019 08:58:47 -0700 (PDT) Date: Tue, 30 Jul 2019 08:58:47 -0700 From: "Paul E. McKenney" To: Alan Stern Cc: "Joel Fernandes (Google)" , linux-kernel@vger.kernel.org, Akira Yokosawa , Andrea Parri , Boqun Feng , Daniel Lustig , David Howells , Ingo Molnar , Jade Alglave , linux-arch@vger.kernel.org, Luc Maranget , Nicholas Piggin , Peter Zijlstra , Will Deacon Subject: Re: [PATCH] Use term cumul-fence instead of fence in ->prop ordering example Message-ID: <20190730155847.GW14271@linux.ibm.com> Reply-To: paulmck@linux.ibm.com References: <20190729123605.150423-1-joel@joelfernandes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-07-30_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1907300165 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 29, 2019 at 04:41:34PM -0400, Alan Stern wrote: > On Mon, 29 Jul 2019, Joel Fernandes (Google) wrote: > > > To reduce ambiguity in the more exotic ->prop ordering example, let us > > use the term cumul-fence instead fence for the 2 fences, so that the > > implict ->rfe on loads/stores to Y are covered by the description. > > > > Link: https://lore.kernel.org/lkml/20190729121745.GA140682@google.com > > > > Suggested-by: Alan Stern > > Signed-off-by: Joel Fernandes (Google) > > --- > > tools/memory-model/Documentation/explanation.txt | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/tools/memory-model/Documentation/explanation.txt b/tools/memory-model/Documentation/explanation.txt > > index 68caa9a976d0..634dc6db26c4 100644 > > --- a/tools/memory-model/Documentation/explanation.txt > > +++ b/tools/memory-model/Documentation/explanation.txt > > @@ -1302,7 +1302,7 @@ followed by an arbitrary number of cumul-fence links, ending with an > > rfe link. You can concoct more exotic examples, containing more than > > one fence, although this quickly leads to diminishing returns in terms > > of complexity. For instance, here's an example containing a coe link > > -followed by two fences and an rfe link, utilizing the fact that > > +followed by two cumul-fences and an rfe link, utilizing the fact that > > release fences are A-cumulative: > > > > int x, y, z; > > @@ -1334,10 +1334,10 @@ If x = 2, r0 = 1, and r2 = 1 after this code runs then there is a prop > > link from P0's store to its load. This is because P0's store gets > > overwritten by P1's store since x = 2 at the end (a coe link), the > > smp_wmb() ensures that P1's store to x propagates to P2 before the > > -store to y does (the first fence), the store to y propagates to P2 > > +store to y does (the first cumul-fence), the store to y propagates to P2 > > before P2's load and store execute, P2's smp_store_release() > > guarantees that the stores to x and y both propagate to P0 before the > > -store to z does (the second fence), and P0's load executes after the > > +store to z does (the second cumul-fence), and P0's load executes after the > > store to z has propagated to P0 (an rfe link). > > > > In summary, the fact that the hb relation links memory access events > > Acked-by: Alan Stern Queued with Alan's ack, thank you both! Thanx, Paul