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: [PATCH] Re: cc-mode fontification feels random Date: Tue, 31 Aug 2021 16:02:45 +0000 Message-ID: References: <835yvmka50.fsf@gnu.org> <9377d9ec-a3e5-ceea-8a9a-523a420f13f7@dancol.org> <83v93lsq83.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="4341"; mail-complaints-to="usenet@ciao.gmane.io" Cc: dancol@dancol.org, monnier@iro.umontreal.ca, emacs-devel@gnu.org To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Tue Aug 31 18:11:12 2021 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 1mL6Lw-0000tv-0q for ged-emacs-devel@m.gmane-mx.org; Tue, 31 Aug 2021 18:11:12 +0200 Original-Received: from localhost ([::1]:59462 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mL6Lu-0006Hx-PA for ged-emacs-devel@m.gmane-mx.org; Tue, 31 Aug 2021 12:11:10 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:36274) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mL6Dr-0008Bu-47 for emacs-devel@gnu.org; Tue, 31 Aug 2021 12:02:51 -0400 Original-Received: from colin.muc.de ([193.149.48.1]:38572 helo=mail.muc.de) by eggs.gnu.org with smtp (Exim 4.90_1) (envelope-from ) id 1mL6Dp-0003Yp-4C for emacs-devel@gnu.org; Tue, 31 Aug 2021 12:02:50 -0400 Original-Received: (qmail 60344 invoked by uid 3782); 31 Aug 2021 16:02:46 -0000 Original-Received: from acm.muc.de (p4fe158c5.dip0.t-ipconnect.de [79.225.88.197]) (using STARTTLS) by colin.muc.de (tmda-ofmipd) with ESMTP; Tue, 31 Aug 2021 18:02:45 +0200 Original-Received: (qmail 5367 invoked by uid 1000); 31 Aug 2021 16:02:45 -0000 Content-Disposition: inline In-Reply-To: <83v93lsq83.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 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:273606 Archived-At: Hello, Eli. On Tue, Aug 31, 2021 at 16:23:08 +0300, Eli Zaretskii wrote: > > Date: Tue, 31 Aug 2021 10:54:23 +0000 > > Cc: Daniel Colascione , Eli Zaretskii , > > emacs-devel@gnu.org > > From: Alan Mackenzie > > For my current project (finding CC Mode "found types") stealth > > fontification is not ideal - what I need is a single pass through the > > whole buffer to detect the types, and that should be as fast as > > possible. The current stealth fontification is not fast (it doesn't > > need to be) and carries on working until Emacs is shut down. > The purpose of jit-lock-stealth is different, that's why. > > So, it seems I want something like stealth, but not quite. > Yes, you want a different feature. > > How about, say jit-lock-single-fontification - it would apply to > > individual buffers only, would scan through the buffer precisely > > once, and would do just enough 500-byte chunks at at time to take > > 0.05 seconds (configurable). > > On my machine in C Mode, approximately 100 chunks are fontified per > > second. So if we had jit-lock-single-nice at 0.1 seconds, the time > > taken to scan xdisp.c would be approximately 1 to 1.5 minutes. On a > > smaller file, say syntax.c (a tenth of the size) it would take 5 - 10 > > seconds. This is barely worse than context fontification, and would > > only happen at mode start up. > What happens if you unleash this jit-lock-single-fontification, and > then type at a relatively slow pace: does Emacs still feel responsive > enough? And how much of CPU does it use in that case? I'm guessing at the moment, but I'm reckoning that if jit-lock-single-fontification uses (marginally over) 0.05s at a time, followed by (at least) 0.1s break, normal typing at up to ten characters per second shouldn't be affected. Am I being optimistic here? I think you said in another post that your system's response with stealth sometimes is "under a second". That sounds like "not very much" under a second, which is sluggish and something we want to avoid. As for how much CPU, then I think it would use one third of a single core's CPU time on an otherwise idle Emacs. That's 0.05s strenuous activity followed by 0.1s break. -- Alan Mackenzie (Nuremberg, Germany).