Newsgroups: comp.arch,comp.parallel
From: kthanasi@cs.rochester.edu (Leonidas Kontothanassis)
Subject: SCI and relaxed consistency
Organization: University of Rochester Computer Science Department
Date: Wed, 8 Feb 1995 14:05:17 GMT
Message-ID: <1995Feb6.214923.5452@cs.rochester.edu>


Hello everybody,

I was wondering about the SCI protocol and whether it is possible to
support release consistency on top of it.  My understanding is that
when a processor wants to write a block the write request goes through
this linked list of sharing processors and the write is allowed to
proceed when the request has come back to the writing processor.  This
way you can definitely support sequential consistency but it is not
clear how you can support relaxed models.  In a relaxed model you do
not need all processor to acknowledge the write, you simply need to
make sure that no two processor write at the same time.  The home node
at DASH lets you do just that.  Is there something in SCI that would
let you do something similar?  Or in general how can one support
relaxed consistency with SCI.

Please respond by e-mail if possible,
Thanks
Leonidas


