From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752073AbeDJVKM (ORCPT ); Tue, 10 Apr 2018 17:10:12 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:40428 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751546AbeDJVKL (ORCPT ); Tue, 10 Apr 2018 17:10:11 -0400 Subject: Re: [PATCH] memory-model: fix cheat sheet typo To: paulmck@linux.vnet.ibm.com Cc: linux-kernel@vger.kernel.org, Alan Stern , Andrea Parri , Will Deacon , Peter Zijlstra , Boqun Feng , Nicholas Piggin , David Howells , Jade Alglave , Luc Maranget , Akira Yokosawa References: <1523292618-10207-1-git-send-email-pbonzini@redhat.com> <20180409184258.GP3948@linux.vnet.ibm.com> <20180410203214.GA19606@linux.vnet.ibm.com> From: Paolo Bonzini Openpgp: preference=signencrypt Autocrypt: addr=pbonzini@redhat.com; prefer-encrypt=mutual; keydata= xsEhBFRCcBIBDqDGsz4K0zZun3jh+U6Z9wNGLKQ0kSFyjN38gMqU1SfP+TUNQepFHb/Gc0E2 CxXPkIBTvYY+ZPkoTh5xF9oS1jqI8iRLzouzF8yXs3QjQIZ2SfuCxSVwlV65jotcjD2FTN04 hVopm9llFijNZpVIOGUTqzM4U55sdsCcZUluWM6x4HSOdw5F5Utxfp1wOjD/v92Lrax0hjiX DResHSt48q+8FrZzY+AUbkUS+Jm34qjswdrgsC5uxeVcLkBgWLmov2kMaMROT0YmFY6A3m1S P/kXmHDXxhe23gKb3dgwxUTpENDBGcfEzrzilWueOeUWiOcWuFOed/C3SyijBx3Av/lbCsHU Vx6pMycNTdzU1BuAroB+Y3mNEuW56Yd44jlInzG2UOwt9XjjdKkJZ1g0P9dwptwLEgTEd3Fo UdhAQyRXGYO8oROiuh+RZ1lXp6AQ4ZjoyH8WLfTLf5g1EKCTc4C1sy1vQSdzIRu3rBIjAvnC tGZADei1IExLqB3uzXKzZ1BZ+Z8hnt2og9hb7H0y8diYfEk2w3R7wEr+Ehk5NQsT2MPI2QBd wEv1/Aj1DgUHZAHzG1QN9S8wNWQ6K9DqHZTBnI1hUlkp22zCSHK/6FwUCuYp1zcAEQEAAc0f UGFvbG8gQm9uemluaSA8Ym9uemluaUBnbnUub3JnPsLBTQQTAQIAIwUCVEJ7AwIbAwcLCQgH AwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJEH4VEAzNNmmxNcwOniaZVLsuy1lW/ntYCA0Caz0i sHpmecK8aWlvL9wpQCk4GlOX9L1emyYXZPmzIYB0IRqmSzAlZxi+A2qm9XOxs5gJ2xqMEXX5 FMtUH3kpkWWJeLqe7z0EoQdUI4EG988uv/tdZyqjUn2XJE+K01x7r3MkUSFz/HZKZiCvYuze VlS0NTYdUt5jBXualvAwNKfxEkrxeHjxgdFHjYWhjflahY7TNRmuqPM/Lx7wAuyoDjlYNE40 Z+Kun4/KjMbjgpcF4Nf3PJQR8qXI6p3so2qsSn91tY7DFSJO6v2HwFJkC2jU95wxfNmTEUZc znXahYbVOwCDJRuPrE5GKFd/XJU9u5hNtr/uYipHij01WXal2cce1S5mn1/HuM1yo1u8xdHy IupCd57EWI948e8BlhpujUCU2tzOb2iYS0kpmJ9/oLVZrOcSZCcCl2P0AaCAsj59z2kwQS9D du0WxUs8waso0Qq6tDEHo8yLCOJDzSz4oojTtWe4zsulVnWV+wu70AioemAT8S6JOtlu60C5 dHgQUD1Tp+ReXpDKXmjbASJx4otvW0qah3o6JaqO79tbDqIvncu3tewwp6c85uZd48JnIOh3 utBAu684nJakbbvZUGikJfxd887ATQRUQnHuAQgAx4dxXO6/Zun0eVYOnr5GRl76+2UrAAem Vv9Yfn2PbDIbxXqLff7oyVJIkw4WdhQIIvvtu5zH24iYjmdfbg8iWpP7NqxUQRUZJEWbx2CR wkMHtOmzQiQ2tSLjKh/cHeyFH68xjeLcinR7jXMrHQK+UCEw6jqi1oeZzGvfmxarUmS0uRuf fAb589AJW50kkQK9VD/9QC2FJISSUDnRC0PawGSZDXhmvITJMdD4TjYrePYhSY4uuIV02v02 8TVAaYbIhxvDY0hUQE4r8ZbGRLn52bEzaIPgl1p/adKfeOUeMReg/CkyzQpmyB1TSk8lDMxQ zCYHXAzwnGi8WU9iuE1P0wARAQABwsEzBBgBAgAJBQJUQnHuAhsMAAoJEH4VEAzNNmmxp1EO oJy0uZggJm7gZKeJ7iUpeX4eqUtqelUw6gU2daz2hE/jsxsTbC/w5piHmk1H1VWDKEM4bQBT uiJ0bfo55SWsUNN+c9hhIX+Y8LEe22izK3w7mRpvGcg+/ZRG4DEMHLP6JVsv5GMpoYwYOmHn plOzCXHvmdlW0i6SrMsBDl9rw4AtIa6bRwWLim1lQ6EM3PWifPrWSUPrPcw4OLSwFk0CPqC4 HYv/7ZnASVkR5EERFF3+6iaaVi5OgBd81F1TCvCX2BEyIDRZLJNvX3TOd5FEN+lIrl26xecz 876SvcOb5SL5SKg9/rCBufdPSjojkGFWGziHiFaYhbuI2E+NfWLJtd+ZvWAAV+O0d8vFFSvr iy9enJ8kxJwhC0ECbSKFY+W1eTIhMD3aeAKY90drozWEyHhENf4l/V+Ja5vOnW+gCDQkGt2Y 1lJAPPSIqZKvHzGShdh8DduC0U3xYkfbGAUvbxeepjgzp0uEnBXfPTy09JGpgWbg0w91GyfT /ujKaGd4vxG2Ei+MMNDmS1SMx7wu0evvQ5kT9NPzyq8R2GIhVSiAd2jioGuTjX6AZCFv3ToO 53DliFMkVTecLptsXaesuUHgL9dKIfvpm+rNXRn9wAwGjk0X/A== Message-ID: <8cbda122-6aa3-365b-fd09-52dca0644cbd@redhat.com> Date: Tue, 10 Apr 2018 23:10:06 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <20180410203214.GA19606@linux.vnet.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/04/2018 22:32, Paul E. McKenney wrote: > On Mon, Apr 09, 2018 at 11:42:58AM -0700, Paul E. McKenney wrote: >> On Mon, Apr 09, 2018 at 06:50:15PM +0200, Paolo Bonzini wrote: >>> "RWM" should be "RMW", and that's more or less the extent to which I >>> can claim to change the document. :) In particular, "Self" is not >>> documented and the difference between "Self" and "SV" is not clear >>> to me. >>> >>> Signed-off-by: Paolo Bonzini >> >> Applied, though without the questions. ;-) >> >> "Self" is for things like smp_load_acquire() and smp_store_release() >> that order themselves against later and earlier accesses, respectively. >> This ordering applies to later/earlier access to all variables, not >> just the one that smp_load_acquire()/smp_store_release() accessed. >> In contrast, things like smp_mb() order only other accesses, not >> themselves. Or at least it is impossible to proves whether or not they >> order themselves because they are not separately visible to other CPUs. >> >> "SV" is "same variable", which applies to pretty much anything that >> accesses a variable, but not to things like smp_mb() which do not. >> >> Does that help? > > On the perhaps naive assumption that silence means assent, how about > the following patch? Silence meant "I tried thinking of a patch myself, and hadn't come up yet with a fully satisfactory one"; that's some kind of assent I guess. :) Your patch is certainly an improvement! Thanks, Paolo > Thanx, Paul > > ------------------------------------------------------------------------ > > commit 818e46e8db6cacb099b8640b7f2945a3151c00ab > Author: Paul E. McKenney > Date: Tue Apr 10 13:24:19 2018 -0700 > > tools/memory-order: Improve key for SELF and SV > > The key for "SELF" was missing completely and the key for "SV" was > a bit obtuse. This commit therefore adds a key for "SELF" and improves > the one for "SV". > > Reported-by: Paolo Bonzini > Signed-off-by: Paul E. McKenney > > diff --git a/tools/memory-model/Documentation/cheatsheet.txt b/tools/memory-model/Documentation/cheatsheet.txt > index c0eafdaddfa4..d502993ac7d2 100644 > --- a/tools/memory-model/Documentation/cheatsheet.txt > +++ b/tools/memory-model/Documentation/cheatsheet.txt > @@ -26,4 +26,5 @@ Key: C: Ordering is cumulative > DR: Dependent read (address dependency) > DW: Dependent write (address, data, or control dependency) > RMW: Atomic read-modify-write operation > - SV Same-variable access > + SELF: Orders self, as opposed to accesses both before and after > + SV: Orders later accesses to the same variable >