Gavin Scott wrote:
>
> m555 writes:
> > On 28 Feb 2000 22:02:22 GMT, [log in to unmask] (47u) wrote:
> > >The jump from the /800 to /1000 is due to new software features that
> > >are only enabled on 10-way and 12-way systems running 6.5.
> >
> > Like what? And why can't they be enabled on fewer CPUs?
>
> I would *guess* that there are no features that get "enabled" when you go
> from 8 to 10 cpus, but that the changes made to MPE involved primarily
> eliminating resource contention (i.e the locking of semaphores around access
> to shared system structures, etc.) which was limiting the 10-way and 12-way
> boxes to probably about the same performance as the 8-way models.
>
> As far as I know, these changes should have some benefit for *all*
> multi-processor 3000s, but they probably won't be noticed as much on the
> lower "-way" boxes.
>
> G.

Gavin hit the nail on the head.  Portions of the memory manager and
process management were rewritten in 6.5 to remove contention on
semaphores that becomes noticable in 8-way servers and above.  In fact
for most applications on Release 6.0 and earlier, you get virtually no
performance increase above 8 way.  That's why Release 6.5 is required to
go to 10 and 12-way.  (You should also note that you need authorized HP
folks to do the installation or the new 10 and 12-way 997 server will
not work.)

The changes in 6.5 actually also have some small benefit on 997 Servers
at 8-way (went from 36.4 on Release 6.0 to 39.0 on Release 6.5) and
6-way 989KS/650 servers (went from 41.7 on Release 6.0 to 43.8 on
Release 6.5).  Improvements were not noticable at lower ways of MP.

Hope that helps,
Dave Snow
HP CSY Product Marketing