From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: MPS signals and Emacs Date: Mon, 22 Apr 2024 13:46:50 +0300 Message-ID: <86o7a165et.fsf@gnu.org> References: <878r16n5jl.fsf@gmail.com> <87ttjulb16.fsf@gmail.com> <86a5ll7wj9.fsf@gnu.org> <71431fc4-2ab2-4778-88df-25d4e315d737@cs.ucla.edu> <00fec231-a625-406e-a51b-cb66710c6482@cs.ucla.edu> <86wmop6cot.fsf@gnu.org> <86v8496ajl.fsf@gnu.org> <86ttjt69i2.fsf@gnu.org> <86sezd68g8.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="20966"; mail-complaints-to="usenet@ciao.gmane.io" Cc: eggert@cs.ucla.edu, eller.helmut@gmail.com, emacs-devel@gnu.org To: Gerd =?utf-8?Q?M=C3=B6llmann?= Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Mon Apr 22 12:47:46 2024 Return-path: Envelope-to: ged-emacs-devel@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 1ryrD6-0005HS-RU for ged-emacs-devel@m.gmane-mx.org; Mon, 22 Apr 2024 12:47:44 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ryrCO-0008Oe-DK; Mon, 22 Apr 2024 06:47:00 -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 1ryrCM-0008Nm-I6 for emacs-devel@gnu.org; Mon, 22 Apr 2024 06:46:58 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ryrCL-000835-JQ; Mon, 22 Apr 2024 06:46:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=gnu.org; s=fencepost-gnu-org; h=MIME-version:References:Subject:In-Reply-To:To:From: Date; bh=symAgExmAJKQn8RJtrPZHdSvJQlfAnVwDKSQdybcZtk=; b=Q1Mav8wXIJITPWz1B86a dzcBnKMOQkILFCgrVKRAvX4WlRGfCpTM2x2tKUZsBpV/H488GTg6inXXC9UPEDX88WzY+dFFaJLWu rCkWUf9SpqhVMBX4WbM0Rul34ifeCktJAd7Djd8+Xs0XKfEoiezZhbK8EgvyztlcZd4EpwzyjAF07 D0Cv35BsUIeUXF9zc2dSynU2n5UCwAvQGxOWPRYwEr/T1HjvIQOd8eJuLr+xwWLp558zlpFtipana XvV90Xho9rzr7TXvFQld5D1eD560uVRmUSlz7oCSseCVJzpLfKzwQBNiIhLULq5mclxk4sYDVvQUB n2Ba3qkAEAjgow==; In-Reply-To: (message from Gerd =?utf-8?Q?M?= =?utf-8?Q?=C3=B6llmann?= on Mon, 22 Apr 2024 12:22:25 +0200) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 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-mx.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:317972 Archived-At: > From: Gerd Möllmann > Cc: eggert@cs.ucla.edu, eller.helmut@gmail.com, emacs-devel@gnu.org > Date: Mon, 22 Apr 2024 12:22:25 +0200 > > Now a GC happens. We can copy objects from a pages in from-space to a > page in to-soace, and everything works as in the copying collector, in > principle. At the end, we just switch what we consider to-space and > from-space. Maybe a 1 in the page info data structure formerly stood for > to-space and 0 for to-space. Now exchange the meaning of 0 and 1. > > Ok, I hope. Now say we have an ambiguous reference to an object O in > page P. We can copy the objects as above, but not O, which we leave > where it is. At the end of the GC, we move P to to-space by simply > changing its number in the page info data. Mission accomplished. I don't understand this part: At the end of the GC, we move P to to-space by simply changing its number in the page info data. What is "its number" here? Since all the live objects that could be copied were copied from P to to-space, we now have a single object O in P (which is in from-space) and all the rest in to-space. Now comes that magic sentence where I got lost, and somehow "moves P to to-space". How does it do that? And why move P to to-space in the first place, when all of its objects except O are already copied to to-space?