From:	NORLMN::EVERHART      2-APR-1997 14:33:26.35
To:	STAR::ZALEWSKI
CC:	EVERHART
Subj:	Galaxy locks

Steve -
I read through the Galaxy IR last night. This may be a result of it having
been late when I got to locks, but just in case...

I noticed discussion of a galactic spinlock accessing the lock database.
This to a degree bothers me.

The reason clusters scale as they do is in part that locks are all
held locally, maybe mastered somewhere else, but J random priv'd code
that wants to peek at a lock gets a spinlock only on his machine,
not all over, most of the time. Thus replicating locks and having them
mastered somewhere is good for scaling.

I can see that having the data for mastering held someplace shareable
for each processor, and a separate someplace for each set of master
stuff, could be a win, since each separate someplace could be controlled
by a different spinlock and copying from there with the spinlock could
be a win over interrupting and doing network stuff. However I wasn't
sure from what I read that such a scheme was what is intended or
recommended. Glomming all the lock masters together and having ONE
lock for the lot of them seems likely not to scale...I hope that is
not the plan.

Glenn Everhart