From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Gregory Heytings via "Emacs development discussions." Newsgroups: gmane.emacs.devel Subject: Re: The Emacs master is much slower than the emacs-27 branch. Date: Fri, 04 Dec 2020 19:27:37 +0000 Message-ID: References: <877dpyzg9d.fsf@rub.de> <87czzpsyqn.fsf@gmx.net> <83o8j9eqwx.fsf@gnu.org> <874kl1spe9.fsf@gmx.net> <83blf9em55.fsf@gnu.org> <87zh2tr82r.fsf@gmx.net> <87v9dhr7i5.fsf@gmx.net> <838sadefiw.fsf@gnu.org> Reply-To: Gregory Heytings Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="4600"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Alpine 2.22 (NEB 394 2020-01-19) Cc: Stephen Berman , acm@muc.de, emacs-devel@gnu.org To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Fri Dec 04 21:56:32 2020 Return-path: Envelope-to: ged-emacs-devel@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1klI7z-00017h-NO for ged-emacs-devel@m.gmane-mx.org; Fri, 04 Dec 2020 21:56:31 +0100 Original-Received: from localhost ([::1]:47510 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1klI7y-00067A-Pe for ged-emacs-devel@m.gmane-mx.org; Fri, 04 Dec 2020 15:56:30 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:47210) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1klGkQ-00011q-Tt for emacs-devel@gnu.org; Fri, 04 Dec 2020 14:28:07 -0500 Original-Received: from mx.sdf.org ([205.166.94.24]:49272) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1klGkH-0006zA-KI; Fri, 04 Dec 2020 14:28:04 -0500 Original-Received: from sdf.org (IDENT:ghe@faeroes.freeshell.org [205.166.94.9]) by mx.sdf.org (8.15.2/8.14.5) with ESMTPS id 0B4JReOR017351 (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256 bits) verified NO); Fri, 4 Dec 2020 19:27:40 GMT Original-Received: (from ghe@localhost) by sdf.org (8.15.2/8.12.8/Submit) id 0B4JRdt7008056; Fri, 4 Dec 2020 19:27:39 GMT In-Reply-To: <838sadefiw.fsf@gnu.org> Received-SPF: pass client-ip=205.166.94.24; envelope-from=ghe@sdf.org; helo=mx.sdf.org X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.23 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-mx.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.io gmane.emacs.devel:260317 Archived-At: >>> I just rebuilt emacs-27 with "make bootstrap", reran the benchmark, >>> and it took ~60 seconds, about a second faster than the previous >>> non-bootstrapped build. The profile is similar to the previous one >>> from emacs-27, but I've attached for your perusal anyway. I'll >>> bootstrap master too and run the benchmark there again. >> >> On freshly bootstrapped master the benchmark took the same time as >> before, ~21 seconds, and the profile looks pretty much the same, so I >> haven't attached it, but will send it if you want to see it. > > Thanks. This is very strange. What are the build options and the > features in each build? are they identical? > Indeed with CFLAGS='-Og -g3', on my computer (Debian GNU/Linux, GCC 10.2.0) with 28.0.50 this benchmark takes 25.2 seconds, whereas with 27.1.50 it takes 67.6 seconds. I bisected this, and the origin of the regression is commit 365dad197bac5deec9244fd9c189d23c46c99b31, which changes the default to "use 'static' instead of 'extern inline' [in C headers] because 'static' typically has better performance for Emacs". With -Og or -O0, the benchmark takes 67 seconds, with -O1 or above (-O2 is the default) it takes 25 seconds. Emacs 28.0.50 uses 'static inline' instead of 'extern inline' again, "because 'static inline' has much better performance for Emacs when compiled with 'gcc -Og'" (see src/conf_post.h).