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From: yak%dove@gatech.edu (Yousef A. Khalidi)
Newsgroups: comp.os.research
Subject: Re: Question for the week -- distributed Multics?
Message-ID: <6227@saturn.ucsc.edu>
Date: 3 Feb 89 19:06:47 GMT
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Organization: The Clouds/Ra Project, School of ICS, Georgia Tech
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Approved: comp-os-research@jupiter.ucsc.edu


I have been working on memory management support for operating systems with
my advisor, Kishore Ramachandran, for the last year and half. Specifically,
we are looking at memory management support for the programming model of
Clouds/Ra, at each node in the distributed system, as well as network-wide
memory management. Distributed shared memory (DSM) is the tool used for
network-wide memory management, and it fits nicely with the Ra kernel.  The
Ra kernel have segment manipulation primitives that borrow ideas from
Multics. Using DSM, any segment in the network may be accessed regardless of
its location. We use the mechanisms to implement remote object invocation (as
an alternative for RPC) by paging-in (portions of) the required segments and
performing the invocation locally. (The system also provides RPC and the
choice of which mechanism to use is left for the programmer/compiler/OS.)

The DSM mechanisms are also used for all paging across the network, and to
implement process and object migration.  We combine locking with memory
coherency, and address the issue of synchronization. DSM mechanisms provide
semaphore operations that can be performed at any node in the system (by
moving the segment containing the semaphore to that node). I have several
tech reports that describe the design and implementation of DSM and Ra if you
are interested.

Yousef
-- 
Yousef A. Khalidi --- The Clouds/Ra Project
School of Information & Computer Science, Georgia Tech, Atlanta GA 30332
Internet:  yak@gatech.edu	
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