From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Daniel Colascione Newsgroups: gmane.emacs.devel Subject: Re: Time to drop the pre-dump phase in the build? Date: Fri, 10 Jan 2014 14:19:24 -0800 Message-ID: <52D071EC.4090607@dancol.org> References: <20140110191530.5772E38019B@snark.thyrsus.com> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Trace: ger.gmane.org 1389392378 21055 80.91.229.3 (10 Jan 2014 22:19:38 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 10 Jan 2014 22:19:38 +0000 (UTC) To: "Eric S. Raymond" , emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Fri Jan 10 23:19:44 2014 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1W1kQZ-0003RV-Ri for ged-emacs-devel@m.gmane.org; Fri, 10 Jan 2014 23:19:43 +0100 Original-Received: from localhost ([::1]:59311 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W1kQZ-0006AR-C3 for ged-emacs-devel@m.gmane.org; Fri, 10 Jan 2014 17:19:43 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:58175) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W1kQW-0006AL-FW for emacs-devel@gnu.org; Fri, 10 Jan 2014 17:19:41 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1W1kQV-00071T-9N for emacs-devel@gnu.org; Fri, 10 Jan 2014 17:19:40 -0500 Original-Received: from dancol.org ([2600:3c01::f03c:91ff:fedf:adf3]:38196) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W1kQU-000713-S8 for emacs-devel@gnu.org; Fri, 10 Jan 2014 17:19:39 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=dancol.org; s=x; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:References:Subject:To:MIME-Version:From:Date:Message-ID; bh=6xDenR2fYEYI0L6OT20/lY4fu/VR9IKMKhmNx2OLGL8=; b=hRMEupDNvCtK+itTVuK08rS0m1o04E3gd1/cMWVCUxlf6JgIsU1xfWCegVK6TOKP+6QqscTQrEydADOXC+D8gkrDjlkXZo3UU4EXsEGSLDOy0kzr2Ith1bOb8OIbzNaRZusfVzhue3gSkmJ6ZLykOTueqF9P3qnvjWz0/1HY1h4eDbVfIN45j0fdIUksNvNR/dQtZugzF7dmvWBlWwYYmc1WgkZdEwVr6KIhW7AkUoXknwmsmB9D+i+MSiNMXEWztnWsL7ccOcMFZBE0j8QqXvdzVa3LzOOObG67zHinGhZRUwha7KfU7XSsz8xTfx3DbPS/zoG4j/NfOPqvqFcQCA==; Original-Received: from [2620:0:1cfe:18:863a:4bff:fec8:e538] by dancol.org with esmtpsa (TLS1.0:DHE_RSA_CAMELLIA_256_CBC_SHA1:256) (Exim 4.80) (envelope-from ) id 1W1kQO-0002G5-1U; Fri, 10 Jan 2014 14:19:32 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 In-Reply-To: <20140110191530.5772E38019B@snark.thyrsus.com> X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2600:3c01::f03c:91ff:fedf:adf3 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:168050 Archived-At: On 01/10/2014 11:15 AM, Eric S. Raymond wrote: > My current transition task is still tag cleanup and signing. I'll > report on that shortly. > > I had some off-list conversation with one of our lurkers about > tag cleaning. During it he made an interestingly radical suggestion: > Maybe it's time to stop pre-dumping compiled Lisp into the Emacs build. Disagree. As other benchmarks in this thread indicate, dumping is still a very useful optimization. Besides: the build complexity is well-understood. > While this made sense as a performance hack back in the day, hardware > (most relevantly disk I/O) is much, *much* faster now. And SSDs are > making access to disk not much slower than main memory. Compilation > on demand might be fast enough today. Not everyone has an SSD. > There are good reasons to think about dropping this technique: > > (1) It makes cross-build of Emacs a pain in the ass. Meh? > (3) Back when I last looked at it (admittedly a long time ago) > the dump code was both the largest single source of porting > problems and a serious attractor of crash bugs. That's why the XEmacs portable dumper is better than the current Emacs setup. But not by enough to get distracted with ripping the guts out of the system. > > (4) We're presently buying some startup speed at the cost of a larger > minimum working set. The minimum working set is zero. Modern operating systems demand-page necessary information. The dumped information is file-backed, so the commit charge is zero as well. > under modern cache hierarchies, but I think the question deserves > examination. Unless circumstances have materially change (as they would if, say, non-volatile main memory became common), I don't want to waste time rehashing old debates.