From owner-freebsd-hackers@FreeBSD.ORG Wed Oct 22 04:00:46 2003 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id C9F2016A4B3 for ; Wed, 22 Oct 2003 04:00:46 -0700 (PDT) Received: from smtp101.mail.sc5.yahoo.com (smtp101.mail.sc5.yahoo.com [216.136.174.139]) by mx1.FreeBSD.org (Postfix) with SMTP id 1D54543FD7 for ; Wed, 22 Oct 2003 04:00:44 -0700 (PDT) (envelope-from q_dolan@yahoo.com.au) Received: from q.onthenet.com.au (HELO ?192.168.100.154?) (q?dolan@203.10.89.214 with plain) by smtp.mail.vip.sc5.yahoo.com with SMTP; 22 Oct 2003 11:00:41 -0000 From: Q To: Kris Kennaway In-Reply-To: <20031022095754.GA70026@rot13.obsecurity.org> References: <1066789354.21430.39.camel@boxster.onthenet.com.au> <20031022082953.GA69506@rot13.obsecurity.org> <1066816287.25609.34.camel@boxster.onthenet.com.au> <20031022095754.GA70026@rot13.obsecurity.org> Message-Id: <1066820436.25609.93.camel@boxster.onthenet.com.au> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.5 Date: Wed, 22 Oct 2003 21:00:36 +1000 Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Content-Filtered-By: Mailman/MimeDel 2.1.1 cc: freebsd-hackers@freebsd.org Subject: Re: Some mmap observations compared to Linux 2.6/OpenBSD X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 22 Oct 2003 11:00:47 -0000 Yes, it would appear this is a legacy thing that existed in the original 1994 import of the BSD 4.4 Lite source. Both FreeBSD and NetBSD still use this technique, but OpenBSD changed to using Red-Black trees back in Feb 2002. The actual commit quote reads: "use a red-black tree to find entries in the vm_map. augment the red-black tree to find free space between entries. speeds up memory allocation, etc..." I am wondering if there is a compelling reason why the technique used by OpenBSD could not be adapted to FreeBSD's VM system. Seeya...Q On Wed, 2003-10-22 at 19:57, Kris Kennaway wrote: > On Wed, Oct 22, 2003 at 07:51:28PM +1000, Q wrote: > > Thanks, I have already looked over the repositories to determine how > > they differed. I wasn't really asking about the history of these changes > > in the other projects, but rather the history of why FreeBSD HASN'T also > > gone down this road. There doesn't appear to be anything in CVS or the > > mail archives that I can find that would indicate any intention to > > change the current implementation. > > I'm assuming that FreeBSD has some version of the historical BSD > implementation, and the change was made in OpenBSD (or perhaps NetBSD > before the split), and it has not been considered before in FreeBSD. > I have no familiarity with the code in question, however. > > Kris