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=-1.2 required=3.0 tests=DATE_IN_PAST_06_12, DKIM_INVALID,DKIM_SIGNED,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 91534C0044B for ; Sat, 10 Nov 2018 22:43:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4E4B921104 for ; Sat, 10 Nov 2018 22:43:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="C6Lp8smm" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4E4B921104 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org 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 S1727079AbeKKIaC (ORCPT ); Sun, 11 Nov 2018 03:30:02 -0500 Received: from merlin.infradead.org ([205.233.59.134]:50608 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726868AbeKKIaB (ORCPT ); Sun, 11 Nov 2018 03:30:01 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=iXbJAAf6dw5cHeYZwX8Tjg68v2kN4R31IKI6Ae3Jy3w=; b=C6Lp8smmx9hrYYxiDs2enilZ6 n70/Euj1pazHujtZ8Hee3lcRslCvWEqkdjmwpNUMwJbuQIxFP1atW3LiTVtsC04oJEgDXr/EnUTZa EiEkqusjXrNvivNxmhJaMIjDJjkcArmHPZ0ZOtofM5c4Yn+f/E5EoGxBYhq5+TMYYQxNQItI6edli dhszMnvScNBIY8K3tRtbGNZiramwCSBguk14ux9tNoMWJACCiIkKvnkIFHANIDMRZIe/V3T2NxZA3 a9T9VNzewCbvOaKu2+9z792csNI9zeqraKbPhnaK2538qeimV9joDBDA27uMgSBfQOMzlgYQ0SrgL OAH1RkFWQ==; Received: from [64.114.255.114] (helo=worktop) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gLbyE-0000gI-Ck; Sat, 10 Nov 2018 22:43:15 +0000 Received: by worktop (Postfix, from userid 1000) id 9C6AF6E07E7; Sat, 10 Nov 2018 15:10:45 +0100 (CET) Date: Sat, 10 Nov 2018 15:10:45 +0100 From: Peter Zijlstra To: Ingo Molnar Cc: Waiman Long , Josh Poimboeuf , Ingo Molnar , Will Deacon , Thomas Gleixner , linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, Petr Mladek , Sergey Senozhatsky , Andrey Ryabinin , Tejun Heo , Andrew Morton , Linus Torvalds Subject: Re: [RFC PATCH 00/12] locking/lockdep: Add a new class of terminal locks Message-ID: <20181110141045.GD3339@worktop.programming.kicks-ass.net> References: <1541709268-3766-1-git-send-email-longman@redhat.com> <20181109080412.GC86700@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181109080412.GC86700@gmail.com> User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 09, 2018 at 09:04:12AM +0100, Ingo Molnar wrote: > BTW., if you are interested in more radical approaches to optimize > lockdep, we could also add a static checker via objtool driven call graph > analysis, and mark those locks terminal that we can prove are terminal. > > This would require the unified call graph of the kernel image and of all > modules to be examined in a final pass, but that's within the principal > scope of objtool. (This 'final pass' could also be done during bootup, at > least in initial versions.) Something like this is needed for objtool LTO support as well. I just dread the build time 'regressions' this will introduce :/ The final link pass is already by far the most expensive part (as measured in wall-time) of building a kernel, adding more work there would really suck :/