From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Leo Liu Newsgroups: gmane.emacs.devel Subject: Re: why is reverse a string in-place so much slower than a vector? Date: Fri, 25 Apr 2014 16:17:42 +0800 Message-ID: References: NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1398413936 20948 80.91.229.3 (25 Apr 2014 08:18:56 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 25 Apr 2014 08:18:56 +0000 (UTC) To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Fri Apr 25 10:18:49 2014 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1WdbLM-0005kE-Ty for ged-emacs-devel@m.gmane.org; Fri, 25 Apr 2014 10:18:49 +0200 Original-Received: from localhost ([::1]:56562 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WdbLM-0007cs-Gr for ged-emacs-devel@m.gmane.org; Fri, 25 Apr 2014 04:18:48 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:35962) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WdbKf-0006ae-8v for emacs-devel@gnu.org; Fri, 25 Apr 2014 04:18:12 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WdbKX-00074m-P0 for emacs-devel@gnu.org; Fri, 25 Apr 2014 04:18:05 -0400 Original-Received: from plane.gmane.org ([80.91.229.3]:40185) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WdbKX-000745-IR for emacs-devel@gnu.org; Fri, 25 Apr 2014 04:17:57 -0400 Original-Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1WdbKU-0004Kp-Kv for emacs-devel@gnu.org; Fri, 25 Apr 2014 10:17:54 +0200 Original-Received: from 123.115.255.237 ([123.115.255.237]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 25 Apr 2014 10:17:54 +0200 Original-Received: from sdl.web by 123.115.255.237 with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 25 Apr 2014 10:17:54 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 19 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: 123.115.255.237 Face: iVBORw0KGgoAAAANSUhEUgAAACkAAAApAQAAAACAGz1bAAABKElEQVQYlWNg3NIt5FDPUPt7 4+X79Qyucz5/ugik+L2PBgKpyphaIK921q23QDnG0NBQoMr/vaWl9f8ZLL78uPv5PwN7RETfzXoG jhmFz27XM0RXmpuY/WfY+fv0Mc56BvFybfXA/wwL5t/wF61n2PU59axXPcOVzbmSW/8zrNt1benC /ww70hqUU/4zKCtrT9jwn8FhwynbufUMendE2aLqGRpdX9al1zM8eh17lKeeQcTMrdD5P8P3j/YT Q/8zXHSb7p1Qz/C4OM2JuZ7hgtI7K6AjqsMnf8j4z8C6xG1tw3+GqpqvsVn/GTzmpD9j/8/wP/oZ S/l/Bka+QO/g/wy15ueeFQL9N1O8mPU/g+umV3t1gdT0/1bTgHLqYVeXAlWKpMWt+w8Az82C9nHf X0cAAAAASUVORK5CYII= User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.4.50 (CentOS 6.5) Cancel-Lock: sha1:yIUG41p4ngEHbJE7FkrAPTOGuR8= X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 80.91.229.3 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 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.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:171621 Archived-At: On 2014-04-25 16:12 +0800, Leo Liu wrote: > (defun rev (a) > (let ((l (length a))) > (dotimes (i (floor l 2) a) > (cl-rotatef (aref a i) (aref a (1- (- l i))))))) Sorry didn't finish the post. Assume we are in a buffer visiting subr.el: (benchmark-run 1 (rev (buffer-string))) (11.774416366 1 0.060193897999999635) (benchmark-run 1 (rev (cl-coerce (buffer-string) 'vector))) (0.067042623 0 0.0) So why is this so much slower on string? Leo