From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.bugs Subject: bug#21028: Performance regression in revision af1a69f4d17a482c359d98c00ef86fac835b5fac (Apr 2014). Date: Sun, 16 Apr 2017 10:48:04 +0300 Message-ID: <83fuh8g5e3.fsf@gnu.org> References: <559F9FAF.8090708@live.com> <83lgvd581m.fsf@gnu.org> <83a8br6hq0.fsf@gnu.org> <672a0c69-4352-735f-cba4-025e642626ea@gmail.com> <83vauf50wb.fsf@gnu.org> <7408d59c-92ba-b879-5ac1-3cd5eee9b4db@gmail.com> <83tw9z4zzp.fsf@gnu.org> <2cad0da9-c931-b547-07bb-efec2f2bcf1f@gmail.com> <83h95w0w3p.fsf@gnu.org> <27853273-e6d8-077e-b9e0-b2bec2fe1fae@gmail.com> <834m1v2630.fsf@gnu.org> <1c224dc1-bd71-a910-b7cf-00313e4aec40@live.com> <83efy2cx5n.fsf@gnu.org> <3c3e8384-3412-f5a5-3ab2-a7eb4e699f1c@live.com> <83d1dmcrnl.fsf@gnu.org> <39fe847e-ef8a-149f-4478-d02e7c794c9a@live.com> <837f3tch7y.fsf@gnu.org> <1e7bc066-3f29-3897-5039-de7233efc58a@live.com> <83y3w9ay6y.fsf@gnu.org> <16f9db27-dd0f-ddaf-2f34-45b9fd4e69c6@live.com> <83k27rc15x.fsf@gnu.org> <79f4e3ce-6284-8fc5-fd8f-9f0c9cebe873@live.com> <831styblhv.fsf@gnu.org> <83ziglz1gy.fsf@gnu.org> Reply-To: Eli Zaretskii NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; 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Sun, 16 Apr 2017 03:47:35 -0400 In-reply-to: <83ziglz1gy.fsf@gnu.org> (message from Eli Zaretskii on Thu, 16 Mar 2017 17:27:09 +0200) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 208.118.235.43 X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.org gmane.emacs.bugs:131645 Archived-At: > Date: Thu, 16 Mar 2017 17:27:09 +0200 > From: Eli Zaretskii > Cc: 21028@debbugs.gnu.org > > > Cc: 21028@debbugs.gnu.org > > From: Clément Pit--Claudel > > Date: Wed, 15 Mar 2017 16:46:33 -0400 > > > > > The problem here is that opening a font and looking up a character is > > > very expensive, certainly when there are hundreds of fonts installed. > > > So Emacs filters the fonts according to the scripts they claim to > > > support, and only opens those which appear to be valid candidates for > > > the script of the character it needs to display. By using 'unicode as > > > the script when you set up your fontset, you actually trip Emacs by > > > telling it to try this font for every character it needs to display. > > > You should instead specify the scripts which the fonts supports well. > > > > Ok — but why wasn't it slow in 24.3? > > That's the question about the significance of the zero_vector in the > font-cache, the patch you want to apply. I'm still struggling with > understanding why it speeds up the font search. After looking at the code and discussing with Handa-san, I concluded that we should restore putting the zero_vector in the font-cache when no fonts matching a spec were found. So I've reverted part of the changes introduced during fixing bug#17125, and I'm marking this bug done. If these changes cause some trouble, we will have to debug that when the problems are reported. Thanks.