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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 970AAC05027 for ; Sat, 21 Jan 2023 00:34:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229673AbjAUAel (ORCPT ); Fri, 20 Jan 2023 19:34:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47432 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229448AbjAUAej (ORCPT ); Fri, 20 Jan 2023 19:34:39 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DA2A02115 for ; Fri, 20 Jan 2023 16:34:38 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 59D2A620E3 for ; Sat, 21 Jan 2023 00:34:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A5CEFC433EF; Sat, 21 Jan 2023 00:34:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1674261277; bh=GKPF/KGxBEcGAXCcG9cNchv/GG0zLrZwptY+F/G+TAw=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=ix6xX/9YoKQYV8on68SZFxdIWGcHu8b69tRyxUZf6b0UcTQDbAkHYG0WO+gyaVmo7 KIkNB1mu/PaG9/NznZETyv0/ImoqKXwvQzTGS0RbsY33mLmNAhQYY+4EBS96LYjzoI FcO9i/6MXjCg5TaYwaPJ23zmCLJJhI4zvjj4newdgj2d16KVKEremP4NioZUtIcLHb 5x1tomRTX2/BXyT8Wks27VXvAod2y67s4jHbSQdcEaqZaFQ2ocaBdKh9jRFbE3e4me 42U2zYQvbA14cH59JU22JcEJCxOnsDuAryvVttu9U8GmVVvj1bZC9dmvujt+0z8LOn 2p578XbPkhGQg== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 476F15C0543; Fri, 20 Jan 2023 16:34:37 -0800 (PST) Date: Fri, 20 Jan 2023 16:34:37 -0800 From: "Paul E. McKenney" To: Jonas Oberhauser Cc: Alan Stern , Andrea Parri , Jonas Oberhauser , Peter Zijlstra , will , "boqun.feng" , npiggin , dhowells , "j.alglave" , "luc.maranget" , akiyks , dlustig , joel , urezki , quic_neeraju , frederic , Kernel development list Subject: Re: Internal vs. external barriers (was: Re: Interesting LKMM litmus test) Message-ID: <20230121003437.GB2948950@paulmck-ThinkPad-P17-Gen-1> Reply-To: paulmck@kernel.org References: <20230119184107.GT2948950@paulmck-ThinkPad-P17-Gen-1> <20230119215304.GA2948950@paulmck-ThinkPad-P17-Gen-1> <20230120153909.GF2948950@paulmck-ThinkPad-P17-Gen-1> <20230120213727.GX2948950@paulmck-ThinkPad-P17-Gen-1> <44a2c301-900e-90ea-4b21-e5264102e699@huaweicloud.com> <20230120231952.GZ2948950@paulmck-ThinkPad-P17-Gen-1> <736020be-de00-3cd8-2325-c3efb87e03b6@huaweicloud.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <736020be-de00-3cd8-2325-c3efb87e03b6@huaweicloud.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jan 21, 2023 at 01:03:50AM +0100, Jonas Oberhauser wrote: > > > On 1/21/2023 12:19 AM, Paul E. McKenney wrote: > > On Fri, Jan 20, 2023 at 11:36:15PM +0100, Jonas Oberhauser wrote: > > > > > > On 1/20/2023 10:37 PM, Paul E. McKenney wrote: > > > > Just out of curiosity, are you [set] up to run LKMM locally at your end? > > > I don't know what exactly that means. I generally run it on wetware. > > > But I sometimes ask Hernan to run Dat3M (on his machine) over all the litmus > > > tests in your repo to spot any obvious problems with variations I consider. > > > I don't think Dat3M is feature-complete with herd at the moment, just > > > unbelievably faster. For example I think it ignores all flags in the cat > > > files. > > > Oh, I just remembered that I also installed herd7 recently to make sure that > > > any patches I might send in satisfy herd7 syntax requirements (I think you > > > called this diagnostic driven development?), but I haven't used it to really > > > run anything. > > > > > > Is it too obvious that my words usually aren't backed by cold machine logic? > > Well, there was this in one of your messages from earlier today: "I'm not > > going to get it right today, am I?" And I freely confess that this led > > me to suspect that you might not have been availing yourself of herd7's > > opinion before posting. ;-) > The main reason I might usually not consult herd7's opinion is that it often > takes a while to write a test case in a way herd7 accepts and treats as > intended, but then even so the fact that some tests pass may just give some > false confidence when some tricky case is being missed. > So I find the investment/increased confidence ratio to not yet be at the > right point to do this when communicating somewhat informally on the mailing > list, which is already taking quite a bit of my time (but at least I'm > learning a lot during that time about stuff like RCU/SRCU, history of LKMM, > etc.). > If I need to be more confident I'll use herd7 to make sure the syntax is > correct and as a sanity check, and some paper or Coq proofs to be confident > in the logic. > > If you feel that I'm wasting the lists' time too much by making these kind > of mistakes, let me know and I'll reconsider. Not a goal of mine, actually. The only thing that I will add is that I cheat horribly by creating new litmus tests by existing ones. ;-) Thanx, Paul