From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: pjb@informatimago.com (Pascal J. Bourguignon) Newsgroups: gmane.emacs.help Subject: Re: Vector and List Performance Date: Tue, 09 Jun 2009 11:30:37 +0200 Organization: Anevia SAS Message-ID: <7c63f5n48y.fsf@pbourguignon.anevia.com> References: NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Trace: ger.gmane.org 1244540545 12683 80.91.229.12 (9 Jun 2009 09:42:25 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 9 Jun 2009 09:42:25 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Tue Jun 09 11:42:23 2009 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.50) id 1MDxqW-0003tU-NS for geh-help-gnu-emacs@m.gmane.org; Tue, 09 Jun 2009 11:42:21 +0200 Original-Received: from localhost ([127.0.0.1]:59627 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MDxqV-0007Zl-PS for geh-help-gnu-emacs@m.gmane.org; Tue, 09 Jun 2009 05:42:19 -0400 Original-Path: news.stanford.edu!newsfeed.stanford.edu!goblin2!goblin.stu.neva.ru!newsfeed01.sul.t-online.de!t-online.de!newsfeed.straub-nv.de!proxad.net!feeder1-2.proxad.net!cleanfeed1-a.proxad.net!nnrp14-2.free.fr!not-for-mail Original-Newsgroups: gnu.emacs.help Face: iVBORw0KGgoAAAANSUhEUgAAADAAAAAwAQMAAABtzGvEAAAABlBMVEUAAAD///+l2Z/dAAAA oElEQVR4nK3OsRHCMAwF0O8YQufUNIQRGIAja9CxSA55AxZgFO4coMgYrEDDQZWPIlNAjwq9 033pbOBPtbXuB6PKNBn5gZkhGa86Z4x2wE67O+06WxGD/HCOGR0deY3f9Ijwwt7rNGNf6Oac l/GuZTF1wFGKiYYHKSFAkjIo1b6sCYS1sVmFhhhahKQssRjRT90ITWUk6vvK3RsPGs+M1RuR mV+hO/VvFAAAAABJRU5ErkJggg== X-Accept-Language: fr, es, en X-Disabled: X-No-Archive: no User-Agent: Gnus/5.101 (Gnus v5.10.10) Emacs/22.2 (gnu/linux) Cancel-Lock: sha1:NWExOTc3ZDNhMmFhNDc5YzdiZTAzNDRhMTg1MzVkYTMzZTA3MmQzNQ== Original-Lines: 50 Original-NNTP-Posting-Date: 09 Jun 2009 11:30:37 MEST Original-NNTP-Posting-Host: 88.170.236.224 Original-X-Trace: 1244539837 news-3.free.fr 8111 88.170.236.224:59343 Original-X-Complaints-To: abuse@proxad.net Original-Xref: news.stanford.edu gnu.emacs.help:169852 X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:65083 Archived-At: Nordlöw writes: > I'm trying to figure the performance different between lists and > vectors. Here is my mockup: > > (defun bench (&rest forms) > "Convenience wrapper for benchmark-run-compiled." > (/ (nth 0 (benchmark-run 1024 forms)) 1024)) > > (let ((length 1000000)) > (cons > (bench (aref (make-vector length 0) (/ length 2))) > (bench (nth (/ length 2) (make-list length 0))) > )) > > Strangely I can't seem to find any significant different in > performance when accessing the middle element in a long vector and > long list. Shouldn't the random access performance be the big > difference between vectors and lists? Tyere is. > What have I missed? You have missed that functions receive their argument already evaluated. The argument to each of the calls to bench is 0, in both case. (require 'cl) ; as always (loop with length = 1000000 with index = (1- length) for seq in (list (make-vector length 0) (make-list length 0)) do (insert (format "%8S %s" (type-of seq) (time (loop repeat 100 do (elt seq index)))))) C-x C-e inserts: vector Time: 2.030000e+02 ms cons Time: 7.819890e+05 ms Note however that adding or removing elements from the head, or even in the middle of a list is much faster than doing the same to a vector. -- __Pascal Bourguignon__