From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.help Subject: Re: Passing buffers to function in elisp Date: Wed, 06 Sep 2023 17:12:27 -0400 Message-ID: References: <87mt56hg4e.fsf@iki.fi> <87bklihln8.fsf@iki.fi> <87pm9yf0ph.fsf@web.de> <87v8jmkfd0.fsf@iki.fi> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="33144"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Cc: help-gnu-emacs@gnu.org To: Petteri Hintsanen Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Wed Sep 06 23:14:11 2023 Return-path: Envelope-to: geh-help-gnu-emacs@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 1qdzqk-0008Ps-NE for geh-help-gnu-emacs@m.gmane-mx.org; Wed, 06 Sep 2023 23:14:10 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qdzqB-0007KZ-H0; Wed, 06 Sep 2023 17:13:35 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qdzqA-0007KP-5H for help-gnu-emacs@gnu.org; Wed, 06 Sep 2023 17:13:34 -0400 Original-Received: from mailscanner.iro.umontreal.ca ([132.204.25.50]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qdzq7-0001QA-Nh for help-gnu-emacs@gnu.org; Wed, 06 Sep 2023 17:13:33 -0400 Original-Received: from pmg2.iro.umontreal.ca (localhost.localdomain [127.0.0.1]) by pmg2.iro.umontreal.ca (Proxmox) with ESMTP id A3BE7806AC; Wed, 6 Sep 2023 17:13:29 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=iro.umontreal.ca; s=mail; t=1694034808; bh=SzsahOGrai2qTUCTkvK5rqAokmmpv4h77I+PLxenR+M=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=IrJMa1pCf+RyHy+S4bc+Dor46w44qKYBSBQrCVZADws5XeyaM1R1S/cDUqmKj51/I 6YVPwNhS7/MnM2AeaP/q7e9TGsz4rphe+UO9uf7ebdbjfaF8E37m31nQ+lTOj6YSjv 3id6bePSIUVF40HCO24Dya8rr5CjP4QNFhBZkIQuT0W49iSQqNivaLSWLfhJtRNcyo qs3NiMuuWl73Rs82BUqTxGpUrFGn/IMBZ8BGLMUC+ke58zkm+wTspkGPXpv6iBJ/M1 LNCCTCB3G+rsqRk9SV72FC746hXKVXkLnIIjm2vh2Fsf5Ke79HWXlh9vDlxWCuXbc/ Ye7oTscdKiI4w== Original-Received: from mail01.iro.umontreal.ca (unknown [172.31.2.1]) by pmg2.iro.umontreal.ca (Proxmox) with ESMTP id 4807C803D3; Wed, 6 Sep 2023 17:13:28 -0400 (EDT) Original-Received: from lechazo (lechon.iro.umontreal.ca [132.204.27.242]) by mail01.iro.umontreal.ca (Postfix) with ESMTPSA id 3A29C1201F1; Wed, 6 Sep 2023 17:13:28 -0400 (EDT) In-Reply-To: (Petteri Hintsanen's message of "Wed, 06 Sep 2023 22:05:13 +0300") Received-SPF: pass client-ip=132.204.25.50; envelope-from=monnier@iro.umontreal.ca; helo=mailscanner.iro.umontreal.ca X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.help:145084 Archived-At: >> This is a typical a source of unnecessary O(N=B2) complexity: the above >> line takes O(N) time, so if you do it O(N) times, you got your >> N=B2 blowup. You're usually better off doing [...] > I replaced vconcat with push. However it did not have a significant > effect (measured with Emacs memory profiler). Perhaps the chunks were > quite small after all. That's usually the case, indeed. > In complexity speak, with small N one usually > does not need to worry about quadratics. But: it's rare to be sure that N will *always* be small :-( > I also tried to replace with-temp-buffer forms (such forms are called > hundreds of times) with a static buffer for holding temporary data. It > produced mixed results. In some limited settings, memory savings were > considerable, but in some others cases it blew up memory usage. I > cannot explain why that happened. But it seems safest to stick to > with-temp-buffer. `with-temp-buffer` is fairly costly, but to the extent that it's pretty much a constant cost it shouldn't [known on wood] bring surprises in unexpected circumstances, so if it's fast enough it's a good choice. Stefan