From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Jean Louis Newsgroups: gmane.emacs.devel Subject: Re: Redisplay slower in Emacs 28 than Emacs 27 Date: Mon, 7 Dec 2020 18:21:50 +0300 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="22575"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Mutt/2.0 (3d08634) (2020-11-07) Cc: emacs-devel@gnu.org To: Gregory Heytings Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Mon Dec 07 16:24:47 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 1kmINb-0005lq-RZ for ged-emacs-devel@m.gmane-mx.org; Mon, 07 Dec 2020 16:24:47 +0100 Original-Received: from localhost ([::1]:38010 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kmINa-0007ET-TS for ged-emacs-devel@m.gmane-mx.org; Mon, 07 Dec 2020 10:24:46 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:39616) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kmIM0-0005h8-PQ for emacs-devel@gnu.org; Mon, 07 Dec 2020 10:23:08 -0500 Original-Received: from static.rcdrun.com ([95.85.24.50]:54569) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kmILy-0003IL-Vn for emacs-devel@gnu.org; Mon, 07 Dec 2020 10:23:08 -0500 Original-Received: from localhost ([::ffff:197.157.0.57]) (AUTH: PLAIN admin, TLS: TLS1.2,256bits,ECDHE_RSA_AES_256_GCM_SHA384) by static.rcdrun.com with ESMTPSA id 00000000002C0006.000000005FCE48D8.000030BE; Mon, 07 Dec 2020 15:23:03 +0000 Content-Disposition: inline In-Reply-To: Received-SPF: pass client-ip=95.85.24.50; envelope-from=bugs@gnu.support; helo=static.rcdrun.com X-Spam_score_int: 14 X-Spam_score: 1.4 X-Spam_bar: + X-Spam_report: (1.4 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no 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:260483 Archived-At: * Gregory Heytings via "Emacs development discussions. [2020-12-07 17:55]: > > Following the "The Emacs master is much slower than the emacs-27 branch." > thread, I tested Alan's benchmark on the master branch. The platform I used > is a 64-bit GNU/Linux computer, with GCC 10.2. > > It turns out that the 10-15% slowdown of redisplay in Emacs 28, compared to > Emacs 27, is due to a single character change, namely the "!" character > removed in commit 165fd028. > > I attach three graphs of the timings calculated on various revisions of > master. The benchmark ran ten times on each revision; Emacs was compiled > with CFLAGS='-O2'. "timing-1.png" shows that the slowdown happens between > revision 68ff32a5 and 7445560d, "timing-2.png" narrows this to revisions > 4c5043c5 to d3c73fbf, and "timing-3.png" identifies revision 165fd028 as the > cause of the problem. Great work! You may also document how you did that and maybe other people can help in debugging this way "what went wrong".