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=1.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, FSL_HELO_FAKE,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 C1A16C64EAD for ; Tue, 9 Oct 2018 06:15:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5F70B213A2 for ; Tue, 9 Oct 2018 06:15:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="FengMAMc" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5F70B213A2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.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 S1726671AbeJIN2X (ORCPT ); Tue, 9 Oct 2018 09:28:23 -0400 Received: from mail-wr1-f67.google.com ([209.85.221.67]:44924 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726393AbeJIN2X (ORCPT ); Tue, 9 Oct 2018 09:28:23 -0400 Received: by mail-wr1-f67.google.com with SMTP id 63-v6so383206wra.11 for ; Mon, 08 Oct 2018 23:13:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=YD88qprnDrlarseP5uPXj49vRZjipGiZca8ogrXpD68=; b=FengMAMcFKc4Xoty98DaX72g1I9YSZ5sAvKf+7SYVVaRTkFynwTJbtR3jU4DAwapqo 4UsPUvx+Qvq2kRxMla4S/2vwkMplioKxczVCIUEq7sGVW30P6wJdp4Poinqp7dE3lJy4 6CCPNtLlzlVQ4iABbkfk8f/6j4esySk+SAGstYFA+8R1Tb9qHie9cLpYSaMIxp4S3HNm snh7/ERhIg3DiJepFMbJynA/itDyE7m2gLdpvVW6WLXk5rA+EYgIEFScaQDWwHHtx1H1 1KiR3UcH8cXx63HAsPYHqUbqXRKRI7h8Ci8tUWIWLb6yzvUf3nyVZyhnKEmoRG+Q3t+8 AGTQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=YD88qprnDrlarseP5uPXj49vRZjipGiZca8ogrXpD68=; b=qeRwUIM3W+pmVogLMPWODWffcyRycf/0e9lFxtmyGutzJgfpdKhne7Z5AJm8QtOUuc Zw8gZJpuiIsYraGQozKpUM/LyrwoSlxxD6ipEqlZLcInxhT0vh7KgSiZlQ6APXwQ6+Pm 8r92FL1Yn7igsDdEMg82V1Iry5oK4CwCkiJqmD+fK7EjwFnfYnHmiOkT/dCRFk+yXQw0 NsCN3Oc+nNqkF1M5nIHQMBCeP2ZRpg7AnwILeStJECVAlor2KsqErPn0w6nDAZJ3x69U en0yxF89ArwfyI2suTlFh/0bp3wd8ScJI0F+YgXkui8JnySEdKcGynYZE4rHzJRpqM/8 kGlA== X-Gm-Message-State: ABuFfoiY7Itwn0jetlr6PvgmB0vA7OL64P/aWIb73+ZV/WWFh/eviemG 8mT8cG55n6RW+EknpMnA2iXdVqLF X-Google-Smtp-Source: ACcGV60zCrjy91jNmf5zl7XqeApqXHNsbf8V8NBEePMmF8X66LhC8KGBb6Y9C11Wu4FxoPjqmFB38A== X-Received: by 2002:a5d:46d2:: with SMTP id g18-v6mr18090926wrs.185.1539065584211; Mon, 08 Oct 2018 23:13:04 -0700 (PDT) Received: from gmail.com (2E8B0CD5.catv.pool.telekom.hu. [46.139.12.213]) by smtp.gmail.com with ESMTPSA id j6-v6sm10447615wmd.29.2018.10.08.23.13.03 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 08 Oct 2018 23:13:03 -0700 (PDT) Date: Tue, 9 Oct 2018 08:13:01 +0200 From: Ingo Molnar To: Josh Poimboeuf Cc: Paul Menzel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, LKML Subject: Re: unwind_init() takes 100 ms Message-ID: <20181009061301.GB116930@gmail.com> References: <81a1ff79-b303-c384-f926-c9618afac8f0@molgen.mpg.de> <20181008173417.crlfndi3p5pevnx3@treble> <20181008173614.bchqq6unw65bc57x@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181008173614.bchqq6unw65bc57x@treble> 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 * Josh Poimboeuf wrote: > On Mon, Oct 08, 2018 at 12:34:17PM -0500, Josh Poimboeuf wrote: > > > 4. Would a command line parameter be reasonable `disable_unwind`, so people > > > could decrease their boot time with distribution kernels, and easily turn it > > > back on, when they need a stacktrace without having to rebuild the Linux > > > kernel? > > > > I think a boot cmdline option to disable ORC would be ok. However, > > disabling ORC would need to fall back to the "guess" unwinder. > > Otherwise it would make debugging impossible. That shouldn't be too > > hard, but it would require restructuring the code a bit. > > But I should also clarify that this option wouldn't be worth it. > Sorting at build time is the way to go. Yep, very much so. Thanks, Ingo