From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Alan Mackenzie Newsgroups: gmane.emacs.devel Subject: Re: CC Mode with font-lock-maximum-decoration 2 Date: Mon, 8 Aug 2022 18:41:01 +0000 Message-ID: References: <83y1w0w0gk.fsf@gnu.org> <83pmhcvugm.fsf@gnu.org> <83czdbwjfr.fsf@gnu.org> <837d3jvu9f.fsf@gnu.org> <83sfm6veqa.fsf@gnu.org> <83pmhavdim.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="880"; mail-complaints-to="usenet@ciao.gmane.io" Cc: emacs-devel@gnu.org To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Mon Aug 08 20:46:26 2022 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 1oL7lf-000Ac0-UR for ged-emacs-devel@m.gmane-mx.org; Mon, 08 Aug 2022 20:46:23 +0200 Original-Received: from localhost ([::1]:45536 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oL7le-0003IS-Qr for ged-emacs-devel@m.gmane-mx.org; Mon, 08 Aug 2022 14:46:22 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:53372) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oL7gZ-0000ai-Jk for emacs-devel@gnu.org; Mon, 08 Aug 2022 14:41:07 -0400 Original-Received: from colin.muc.de ([193.149.48.1]:18827 helo=mail.muc.de) by eggs.gnu.org with smtp (Exim 4.90_1) (envelope-from ) id 1oL7gW-00011o-RW for emacs-devel@gnu.org; Mon, 08 Aug 2022 14:41:07 -0400 Original-Received: (qmail 16799 invoked by uid 3782); 8 Aug 2022 18:41:01 -0000 Original-Received: from acm.muc.de (p4fe1582e.dip0.t-ipconnect.de [79.225.88.46]) (using STARTTLS) by colin.muc.de (tmda-ofmipd) with ESMTP; Mon, 08 Aug 2022 20:41:01 +0200 Original-Received: (qmail 8228 invoked by uid 1000); 8 Aug 2022 18:41:01 -0000 Content-Disposition: inline In-Reply-To: <83pmhavdim.fsf@gnu.org> X-Submission-Agent: TMDA/1.3.x (Ph3nix) X-Primary-Address: acm@muc.de Received-SPF: pass client-ip=193.149.48.1; envelope-from=acm@muc.de; helo=mail.muc.de 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_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 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:293280 Archived-At: On Mon, Aug 08, 2022 at 20:41:37 +0300, Eli Zaretskii wrote: > > Date: Mon, 08 Aug 2022 20:15:25 +0300 > > From: Eli Zaretskii > > Cc: emacs-devel@gnu.org > > > For this measurement, I started with subr.el, and appended copies of it > > > to itself, then took functions off the end, to make it the same size as > > > xdisp.c. xdisp.c is 1209233 bytes, my .el buffer was 1209371 bytes. > > > I used M-: (benchmark-run 1 (time-scroll-b)) on each buffer, with: > > > (defun time-scroll-b (&optional arg) ; For use in `benchmark-run'. > > > (condition-case nil > > > (while t > > > (if arg (scroll-down) (scroll-up)) > > > (sit-for 0)) > > > (error nil))) > > > .. The exact results were: > > > (xdisp.c): (5.7370774540000005 9 0.7672129740000013) > > > (elisp): (4.1201735589999995 5 0.42918214299999846). > > > This was, of course, on an optimised build on GNU/Linux using the Linux > > > console, both measurements starting at BOB, having typed and deleted a > > > character to erase existing font-locking. > > Editing source code is more than just scrolling through the text and > > getting it fontified, though. For realistic measurements, you need to > > emulate and time a typical mix of editing operations. > And btw, I'm not sure I understand what you are saying. Are you > saying that level 2 is enough for fontifications in C mode? No. > If so, what are we losing when compared to the value t, and if we don't > lose anything important, why do we need any fontifications beyond what > level 2 gives us? We lose accuracy. That is important to a lot of people, including the many who have sent in bug reports because of lack of accuracy. > And what about the value nil instead of 2? I haven't tried that, yet. > IOW, if you are saying that you consider level 2 to be the recommended > level for C sources, why didn't we make that change long ago? I'm not saying that. I think, on balance, most users prefer the accuracy of level 3 to the speed of level 2. I've got no real evidence for that, however. > For Lisp, btw, the difference between level 2 and t is negligible. > And the same goes for most/all other modes, which is the reason why we > have set the value to t years ago. I'm quite sure at that time the > difference between 2 and t for C mode was also very small. Martin Stjernholm wrote (what has become) the current level 3 around 20 years ago, noting specifically it was expected to be slower than before, and that the new level 2 was comparable in both speed and accuracy to the old level 3. Since then level 3 has become considerably more accurate and quite a bit slower, too. My impression of those times was that the old level 3 was just incapable of being amended to satisfy users' demands for accurate fontification. Again, I'd have to check old CC Mode bug list archives to be sure. -- Alan Mackenzie (Nuremberg, Germany).