Date: Wed, 22 Oct 2003 21:00:36 +1000 From: Q <q_dolan@yahoo.com.au> To: Kris Kennaway <kris@obsecurity.org> Cc: freebsd-hackers@freebsd.org Subject: Re: Some mmap observations compared to Linux 2.6/OpenBSD Message-ID: <1066820436.25609.93.camel@boxster.onthenet.com.au> 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>
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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
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