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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 B95B4C433EF for ; Tue, 14 Sep 2021 11:55:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 91C29610A2 for ; Tue, 14 Sep 2021 11:55:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232315AbhINL4a (ORCPT ); Tue, 14 Sep 2021 07:56:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57958 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232065AbhINL41 (ORCPT ); Tue, 14 Sep 2021 07:56:27 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AF365C061574; Tue, 14 Sep 2021 04:55:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=lbaft6YWSRLzOdeUu5YKqGNKfNQ5U+1pdUU605d2s14=; b=k+cQuR4jbwUsDsSB8nX4cD+lbc OYvYy290iOuaYRLCcT1sFLq7nAjtnal2BkG2YV9KirKJI+I0voCzFBvyb9PzN9v4ZpHJIqQsMh1uH tUmPemdwiEWChCa37euQu1pg6OhFqcFmNASQ656X8gfDaq//ko0a8SSzdHVHToUjzH79nSbuzcvhV LsZG4wbEyQ+arPzXSsgUPfi4HpKJmJ32NZS1caiA1osta3yCcqsPTg9mVCH6y1t1niZNo4jWpJCQf uCOCJ68KZcSTwI+smqFTFHdYFykwIJz14BZWumWjnnYrfTQ7hYTVcQ/OOiMlQ9p6Oc5Jq5EGmy63r fmAJx00Q==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mQ6uN-00EcUW-PY; Tue, 14 Sep 2021 11:47:51 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 69F2D30003A; Tue, 14 Sep 2021 13:47:26 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 5911A2D1FEA08; Tue, 14 Sep 2021 13:47:26 +0200 (CEST) Date: Tue, 14 Sep 2021 13:47:26 +0200 From: Peter Zijlstra To: Leo Yan Cc: Arnaldo Carvalho de Melo , Adrian Hunter , Ingo Molnar , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Thomas Gleixner , Borislav Petkov , "H. Peter Anvin" , Mathieu Poirier , Suzuki K Poulose , Mike Leach , Michael Petlan , "Frank Ch. Eigler" , Song Liu , x86@kernel.org, Daniel =?iso-8859-1?Q?D=EDaz?= , Andrii Nakryiko , Alexei Starovoitov , Sedat Dilek , Andi Kleen , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, coresight@lists.linaro.org Subject: Re: [PATCH v5 4/9] perf/x86: Add compiler barrier after updating BTS Message-ID: References: <20210809111407.596077-1-leo.yan@linaro.org> <20210809111407.596077-5-leo.yan@linaro.org> <20210829105657.GC14461@leoy-ThinkPad-X240s> <20210914100517.GC1538480@leoy-ThinkPad-X240s> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210914100517.GC1538480@leoy-ThinkPad-X240s> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 14, 2021 at 06:05:17PM +0800, Leo Yan wrote: > Hi Peter, > > On Tue, Sep 14, 2021 at 11:51:36AM +0200, Peter Zijlstra wrote: > > On Sun, Aug 29, 2021 at 06:56:57PM +0800, Leo Yan wrote: > > > Hi Peter, or any x86 maintainer, > > > > > > On Mon, Aug 09, 2021 at 07:14:02PM +0800, Leo Yan wrote: > > > > Since BTS is coherent, simply add a compiler barrier to separate the BTS > > > > update and aux_head store. > > > > > > Could you reivew this patch and check if BTS needs the comipler > > > barrier in this case? Thanks. > > > > Yes, a compiler barrier is sufficient. > > > > You want me to pick it up? > > Maybe other maintainers are more suitable than me to answer this :) > > Yeah, I think it's great if you could pick it. OK, done.