On Wed, Jan 29, 2003 at 09:44:59PM -0500, Matthew N. Dodd wrote: > > If we were talking about clustering 32 bit machines with less than 128mb > of memory each that would be true. > > I suppose you could use some sort of PAE to allow every cluster member's > address space to be mapped but a 64 bit address space means that you don't > have to worry as much about this.
Admittedly nobody [that I know of] has a working single system image shared memory Linux cluster outside of SGI[0], and they're using 64-bit hardware. I fully expect that those working on single system image clustering for Linux expect to use it primarily on 64-bit PC hardware once it becomes available. The OpenMosix folks are actually not using a unified address space in thier SSI model. Each node in an OpenMosix cluster runs its own mosix kernel which manages the memory for that node exclusively. When a process is scheduled by the master to run on a particular node then the process' page tables and dirty pages are transferred into memory on the remote node. This is obviously suboptimal and does not support applications which use shared memory. The OpenMosix roadmap does indicate that at some point they plan to add shared memory support. I have not seen any discussion on how they plan to solve the address space limitation. For those who might not be familiar: OpenMosix is a recent fork of the original mosix codebase from Prof. Amnon Barak of the Hebrew University of Jerusalem and his students. At some point Prof. Barak decide to close his source and so a GPL'd replacement sprung up in its place. IIRC mosix was originally written for the US Air Force in the 70s to run on their PDP-11s running Bell Labs' UNIX. It was later ported to BSD/OS before being ported to Linux. I am sure the code to the BSD/OS port is still lurking around somewhere behind an NDA. If someone were interested in bringing this sort of clustering functionality to BSD it might be worth trying to track that code down. [0] - http://www.linuxjournal.com/article.php?sid=6440 Brandon D. Valentine -- [EMAIL PROTECTED] http://www.geekpunk.net "We've been raised on replicas of fake and winding roads, and day after day up on this beautiful stage we've been playing tambourine for minimum wage, but we are real; I know we are real." -- David Berman To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
