🚀 go-pugleaf

In article <1992Sep11.121830.17069@hubcap.clemson.edu>, zilla@nj.nec.com (John Lewis) writes:
> Someone told me that the SGI multiprocessor machines cannot run
> different unix processes on different processors; they can only
> run a single (but possibly parallelized) process at a given time.
> The reason was said to be that the machines do not implement
> any mechanism for simultaneous writes.
> 
> Is this correct?  If so, how are simultaneous writes from
> different threads of a parallelized process prevented?
> 
> Is the new sun multiprocessor (4/690?) similar?

This sounds bogus to me.  All Sun MP machines (4/6xx, SS10, and futures) can
run different processes simultaneously and also run parallelized codes.  I
think your friend is confusing "simultaneous writes" with synchronization.
I believe the SGI machines do something funky to implement barriers (like
put them in a special portion of memory with hardware support) because the
R3000 has no synchronization primitives.  This is not a problem on the Suns
since Sparc has the hooks in the architecture.  R4000 fixes this omission.

			Dave Emberson
			dre@Eng.Sun.COM