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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT 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 74BFCC43382 for ; Thu, 27 Sep 2018 08:13:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2DBD12156B for ; Thu, 27 Sep 2018 08:13:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amarulasolutions.com header.i=@amarulasolutions.com header.b="FK0Ucavr" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2DBD12156B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=amarulasolutions.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727258AbeI0OaX (ORCPT ); Thu, 27 Sep 2018 10:30:23 -0400 Received: from mail-ed1-f66.google.com ([209.85.208.66]:40237 "EHLO mail-ed1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726820AbeI0OaX (ORCPT ); Thu, 27 Sep 2018 10:30:23 -0400 Received: by mail-ed1-f66.google.com with SMTP id j62-v6so4214294edd.7 for ; Thu, 27 Sep 2018 01:13:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amarulasolutions.com; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=pekQ5WX6k8csmXLYb5a3CSizRD09mcOqT4091Kime8c=; b=FK0UcavrMBDz5r/T21/i7zwcbLrNVoXbj1rGkihBbOMFNYo6I7qbq94Jq9EZZxfafY D0ri+ve6vlXNdE0oXtzjCLBJlmyimjUAjoPM2S8ZYrBSK6rgsoYKKjPUicZ+cBTJcvcn MKAYkamolqrgQqs0B8Arl6C2vobzv3fUliH1E= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=pekQ5WX6k8csmXLYb5a3CSizRD09mcOqT4091Kime8c=; b=WhG1ecIXg4e4TUE7UuFWH2hhi5z69fRaUtCoIj7J7zdTrJou42cMLhiw7yZ10zu90l 3uUOFxAG/6w8JB5Y2SPaYyffoZFeJ/G2ipJdzBLkm3ClAGQdIfE0Z28ZebbdQEK08hTv 4X3wCkAVSiZXd1bNme4zInKhH6FGYz69jXRqa5p/lkbT/naGM8vjGCStbUaRjWLiNqgz /VStrqaQujWlKOnxmK3E63kQ2TnkmfmD2wfZ/2BfVXDNvFL7FPFu0X9QTvoHimZziwWg wbqYJlNt9up+qWaa23HW9VOYyyIS5MUmvQtPkfCikKzPBb4JVc4T0ld0XtY9prSA0neG 6X6g== X-Gm-Message-State: ABuFfog5+elCqkyl7L4DDOtMXk4glcfdAZyYaj3xB8M7PzIniK1Q6jLF +6PwoLVZfRjisaGSJtI4fV3teA== X-Google-Smtp-Source: ACcGV60iayI95zMGdho4uQDIAI3vIzC9Mab+HZSY6gEDmuqM6Ck0j25hKzv5Sy++VXiX80U17SvcKA== X-Received: by 2002:a05:6402:6d8:: with SMTP id n24mr15716539edy.99.1538036001321; Thu, 27 Sep 2018 01:13:21 -0700 (PDT) Received: from andrea (85.100.broadband17.iol.cz. [109.80.100.85]) by smtp.gmail.com with ESMTPSA id w23sm437624edv.30.2018.09.27.01.13.20 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 27 Sep 2018 01:13:20 -0700 (PDT) Date: Thu, 27 Sep 2018 10:13:15 +0200 From: Andrea Parri To: Peter Zijlstra Cc: will.deacon@arm.com, mingo@kernel.org, linux-kernel@vger.kernel.org, longman@redhat.com, tglx@linutronix.de Subject: Re: [RFC][PATCH 3/3] locking/qspinlock: Optimize for x86 Message-ID: <20180927081314.GA8285@andrea> References: <20180926110117.405325143@infradead.org> <20180926111307.513429499@infradead.org> <20180926205208.GA4864@andrea> <20180927071747.GD5254@hirez.programming.kicks-ass.net> <20180927074748.GA7939@andrea> <20180927075935.GA4889@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180927075935.GA4889@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 27, 2018 at 09:59:35AM +0200, Peter Zijlstra wrote: > On Thu, Sep 27, 2018 at 09:47:48AM +0200, Andrea Parri wrote: > > > LKMM in particular does _NOT_ deal with mixed sized atomics _at_all_. > > > > True, but it is nothing conceptually new to deal with: there're Cat > > models that handle mixed-size accesses, just give it time. > > Sure, but until that time I must not rely on (and thus not use) LKMM for > qspinlock things. This is way too generic to be agreed ;D > > So while your argument about coherence might be true -- I'll have to > think about it; litmus tests are out the window. You trimmed the litmus test I gave you. Andrea