From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: How and when to use GCPRO? Date: Mon, 27 Dec 2010 23:15:19 -0500 Message-ID: References: <4D193E60.8070108@gmail.com> <4D195B6D.2060305@gmail.com> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: dough.gmane.org 1293509733 20927 80.91.229.12 (28 Dec 2010 04:15:33 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Tue, 28 Dec 2010 04:15:33 +0000 (UTC) Cc: Andreas Schwab , Leo , emacs-devel@gnu.org To: Daniel Colascione Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Tue Dec 28 05:15:28 2010 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1PXQy8-0002pY-CD for ged-emacs-devel@m.gmane.org; Tue, 28 Dec 2010 05:15:28 +0100 Original-Received: from localhost ([127.0.0.1]:43166 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PXQy7-0006tU-9f for ged-emacs-devel@m.gmane.org; Mon, 27 Dec 2010 23:15:27 -0500 Original-Received: from [140.186.70.92] (port=59981 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PXQy2-0006tM-HX for emacs-devel@gnu.org; Mon, 27 Dec 2010 23:15:23 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PXQy1-0002RO-Ny for emacs-devel@gnu.org; Mon, 27 Dec 2010 23:15:22 -0500 Original-Received: from ironport2-out.teksavvy.com ([206.248.154.181]:25741 helo=ironport2-out.pppoe.ca) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PXQy1-0002R7-Ik for emacs-devel@gnu.org; Mon, 27 Dec 2010 23:15:21 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AvsEANbyGE3O+LP+/2dsb2JhbACkKnS/ToVKBIRljhs X-IronPort-AV: E=Sophos;i="4.60,237,1291611600"; d="scan'208";a="86588430" Original-Received: from 206-248-179-254.dsl.teksavvy.com (HELO ceviche.home) ([206.248.179.254]) by ironport2-out.pppoe.ca with ESMTP/TLS/ADH-AES256-SHA; 27 Dec 2010 23:15:20 -0500 Original-Received: by ceviche.home (Postfix, from userid 20848) id C6D496610E; Mon, 27 Dec 2010 23:15:19 -0500 (EST) In-Reply-To: <4D195B6D.2060305@gmail.com> (Daniel Colascione's message of "Mon, 27 Dec 2010 19:37:17 -0800") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.0.50 (gnu/linux) X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:133998 Archived-At: > Hrm. You learn something every day --- I thought Emacs was doing precise > GC the way it has since time immemorial. How much of a win was the > GC_MARK_STACK conservative scanning approach? As long as we still support platforms that use GCPROs, it's not a win at all. Tho it may have beneficial effects on the performance, I don't know (it could also be detrimental to performance, by the way, because of extra work it has to do every time we allocate memory for Lisp objects in order to later on be able to conservatively tell whether an integer happens to point to an allocated memory area). Stefan