From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: ludo@gnu.org (Ludovic =?iso-8859-1?Q?Court=E8s?=) Newsgroups: gmane.lisp.guile.devel Subject: Re: Enormous benchmark speedup Date: Thu, 02 Jul 2009 00:47:06 +0200 Message-ID: <87my7oowb9.fsf@gnu.org> 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 1246488530 16672 80.91.229.12 (1 Jul 2009 22:48:50 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 1 Jul 2009 22:48:50 +0000 (UTC) To: guile-devel@gnu.org Original-X-From: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Thu Jul 02 00:48:44 2009 Return-path: Envelope-to: guile-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.50) id 1MM8ba-0000xI-Kh for guile-devel@m.gmane.org; Thu, 02 Jul 2009 00:48:42 +0200 Original-Received: from localhost ([127.0.0.1]:46732 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MM8bZ-0001sO-Ro for guile-devel@m.gmane.org; Wed, 01 Jul 2009 18:48:41 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MM8aP-00013e-9z for guile-devel@gnu.org; Wed, 01 Jul 2009 18:47:29 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MM8aK-00010v-P3 for guile-devel@gnu.org; Wed, 01 Jul 2009 18:47:28 -0400 Original-Received: from [199.232.76.173] (port=40878 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MM8aK-00010q-GK for guile-devel@gnu.org; Wed, 01 Jul 2009 18:47:24 -0400 Original-Received: from main.gmane.org ([80.91.229.2]:34684 helo=ciao.gmane.org) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1MM8aK-00076c-1H for guile-devel@gnu.org; Wed, 01 Jul 2009 18:47:24 -0400 Original-Received: from list by ciao.gmane.org with local (Exim 4.43) id 1MM8aH-0006gK-LV for guile-devel@gnu.org; Wed, 01 Jul 2009 22:47:21 +0000 Original-Received: from reverse-83.fdn.fr ([80.67.176.83]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 01 Jul 2009 22:47:21 +0000 Original-Received: from ludo by reverse-83.fdn.fr with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 01 Jul 2009 22:47:21 +0000 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 49 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: reverse-83.fdn.fr X-URL: http://www.fdn.fr/~lcourtes/ X-Revolutionary-Date: 14 Messidor an 217 de la =?iso-8859-1?Q?R=E9volution?= X-PGP-Key-ID: 0xEA52ECF4 X-PGP-Key: http://www.fdn.fr/~lcourtes/ludovic.asc X-PGP-Fingerprint: 821D 815D 902A 7EAB 5CEE D120 7FBA 3D4F EB1F 5364 X-OS: x86_64-unknown-linux-gnu User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1.50 (gnu/linux) Cancel-Lock: sha1:DsvFOOAKHkRMXvu4hFdS6SmyZuw= X-detected-operating-system: by monty-python.gnu.org: GNU/Linux 2.6, seldom 2.4 (older, 4) X-BeenThere: guile-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Developers list for Guile, the GNU extensibility library" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Errors-To: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.lisp.guile.devel:8822 Archived-At: Hi! Juhani Viheräkoski writes: > With recent changes in guile vm there are lots on improvements on the > Gambit benchmarks. Improvements compared to what? > In the worst case some test run 10% slower Slower than what? > but there are huge wins in testcases involving vectors offsetting > this. Oh, that's cool, but it feels like we're slightly cheating on these. ;-) > (define (ack m n) > (cond ((= m 0) (+ n 1)) > ((= n 0) (ack (- m 1) 1)) > (else (ack (- m 1) (ack m (- n 1)))))) > > (ack 3 9) This is not tail-recursive (because of the nested `ack' call in the `else' clause), which is why it can lead to a stack overflow. I'm too stupid to compute the maximum "depth" of the call graph, but it looks like this: (ack 3 9) (ack 3 8) <--- X (ack 3 7) ... (ack 3 0) (ack 2 0) ... (ack 0 0) (ack 2 X) (ack 2 (- X 1)) <--- Y ... (ack 1 Y) (ack 1 (- Y 1)) ... Thanks, Ludo'.