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, 21 May 2002 17:35:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 21 May 2002 17:35:11 -0400 Received: from ns.suse.de ([213.95.15.193]:52228 "HELO Cantor.suse.de") by vger.kernel.org with SMTP id ; Tue, 21 May 2002 17:35:10 -0400 To: Dave McCracken Cc: linux-kernel@vger.kernel.org, torvalds@transmeta.com Subject: Re: [RFC] POSIX personality In-Reply-To: <72190000.1022014608@baldur.austin.ibm.com.suse.lists.linux.kernel> From: Andi Kleen Date: 21 May 2002 23:35:09 +0200 Message-ID: X-Mailer: Gnus v5.7/Emacs 20.6 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Dave McCracken writes: > --On Tuesday, May 21, 2002 01:52:37 PM -0700 Linus Torvalds > wrote: > > > I don't see any reason to start using some fixed-mode semantics without > > seeing some stronger arguments on exactly why that would be a good idea. > > We have used up 11 of 24 bits (and more can be made available) over the > > last five years, and there are no obvious inefficiencies that I can see. > > Ok, sounds reasonable. I'll add the bits as I go, then. One reason for it would be that it would be more efficient. All the various shared state needed for POSIX thread group emulation could be put into a single structure with a single reference count. With clone flags you need one pointer in task_struct per flag and handling of the reference count for each data structure and allocation/freeing from various slabs for a real fork. (basically lots of atomic operations at fork time + bloating of task_struct) -Andi