From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 14 Aug 2001 07:49:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 14 Aug 2001 07:49:31 -0400 Received: from alfik.ms.mff.cuni.cz ([195.113.19.71]:23571 "EHLO alfik.ms.mff.cuni.cz") by vger.kernel.org with ESMTP id ; Tue, 14 Aug 2001 07:49:21 -0400 Date: Sat, 11 Aug 2001 01:04:11 +0000 From: Pavel Machek To: Linus Torvalds Cc: Jamie Lokier , "H. Peter Anvin" , linux-kernel@vger.kernel.org Subject: Re: /proc//maps getting _VERY_ long Message-ID: <20010811010411.A55@toy.ucw.cz> In-Reply-To: <20010806194120.A5803@thefinal.cern.ch> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 1.0.1i In-Reply-To: ; from torvalds@transmeta.com on Fri, Aug 10, 2001 at 02:55:11PM -0700 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! > > There are garbage collectors that use mprotect() and SEGV trapping per > > page. It would be nice if there was a way to change the protections per > > page without requiring a VMA for each one. > > This is actually how Linux used to work a long long time ago - all > protection information was in the page tables, and you could do per-page > things without having to worry about piddling details like vma's. > > It does work, but it had major downsides. Trivial things like re-creating > the permission after throwing a page out or swapping it out. For some uses, spurious SEGV after swap-in might be okay ;-). Garbage collector might be that example. Pavel -- Philips Velo 1: 1"x4"x8", 300gram, 60, 12MB, 40bogomips, linux, mutt, details at http://atrey.karlin.mff.cuni.cz/~pavel/velo/index.html.