From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: The Emacs master is much slower than the emacs-27 branch. Date: Sat, 05 Dec 2020 11:33:11 +0200 Message-ID: <83eek4d2co.fsf@gnu.org> 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> <83360le421.fsf@gnu.org> <83y2idcn8q.fsf@gnu.org> <83wnxxcmjr.fsf@gnu.org> <83tut0d7e9.fsf@gnu.org> <83h7p0d37y.fsf@gnu.org> <83ft4kd2ym.fsf@gnu.org> Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="503"; mail-complaints-to="usenet@ciao.gmane.io" Cc: emacs-devel@gnu.org To: ghe@sdf.org, acm@muc.de, stephen.berman@gmx.net Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Sat Dec 05 10:34:22 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 1klTxO-000AaU-5R for ged-emacs-devel@m.gmane-mx.org; Sat, 05 Dec 2020 10:34:22 +0100 Original-Received: from localhost ([::1]:40760 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1klTxN-0004Y1-3N for ged-emacs-devel@m.gmane-mx.org; Sat, 05 Dec 2020 04:34:21 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:35096) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1klTwX-00047V-Bv for emacs-devel@gnu.org; Sat, 05 Dec 2020 04:33:29 -0500 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]:43408) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1klTwV-00081U-S8; Sat, 05 Dec 2020 04:33:27 -0500 Original-Received: from [176.228.60.248] (port=2730 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_256_CBC_SHA1:256) (Exim 4.82) (envelope-from ) id 1klTwU-0006x0-AJ; Sat, 05 Dec 2020 04:33:27 -0500 In-Reply-To: <83ft4kd2ym.fsf@gnu.org> (message from Eli Zaretskii on Sat, 05 Dec 2020 11:20:01 +0200) 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:260348 Archived-At: > Date: Sat, 05 Dec 2020 11:20:01 +0200 > From: Eli Zaretskii > > > Date: Sat, 05 Dec 2020 11:14:25 +0200 > > From: Eli Zaretskii > > Cc: acm@muc.de, stephen.berman@gmx.net, emacs-devel@gnu.org > > > > I wasn't going to ask that, but I would like to point out one more > > potential difference: I didn't compare two builds of master before and > > after that commit. Instead, I timed 32-bit builds of the current > > emacs-27 and master branches which were both built with the following > > optional switches to configure: > > > > --with-wide-int --with-modules --enable-checking=yes,glyphs 'CFLAGS=-O0 -gdwarf-4 -g3' > > > > Again, I don't expect any of this to matter so dramatically, so this > > is just for completeness' sake. > > And one more nit, again for completeness' sake: in both cases I timed > the scrolling through the master branch version of xdisp.c, not each > branch with its version of xdisp.c. It occurred to me that the differences in the relative performance could be due to a different GCC version and/or the effect of inlining on 32-bit code vs 64-bit code produced by GCC. In any case, Alan's original report was for optimized builds, and he observed (although was later unable to reproduce) that Emacs 28 was slower than Emacs 27. So the important part of this is to compare the performance of the optimized (-O2) builds and see if we have any degradation in Emacs 28 in that case.