lsf%abbott@CIT-VAX.ARPA (Sam Finn) (12/14/85)
I have run your context-switching benchmark, with the results shown
below:
execution times (ms):
FATHER.... user: 36300
system: 40
SON.... user: 35240
system: 260
total system time: 300
i.e. 0.08 ms per context-switch
Our system here at CalTech has the old (not the enhanced) CPU and 5 Mbytes of
memory.
As I indicated in a previous correspondence, our experience with Ridges
here at CalTech seems to have been the opposite of the rest of the
reporting user community. ROS is not yet a complete 4.2bsd; however, I
am unaware of exceptions to 4.2, only features unimplemented at this
time. It is certainly closer to 4.2 than many of the local variants and
dialects that I have seen both here at CalTech and at other
Universities.
Our experience with multiuser performance is also better than I have
seen reported by the user community. It is important to remember that a
Ridge is not a Vax, that a Ridge is still a microcomputer (albeit a
supermicro) with a more limited I/O bandwidth than a Vax and thus not
necessarily able to service as many users as a Vax with the same level
of interactive performance despite a faster CPU for number crunching.
Nonetheless, a typical afternoon here will see 5-7 users on one machine
(up to two coming in as remote logins over the network) working
interactively. Yes, you can tell the machine is being used; no, the
response time is adaquate for editing and test-running of programs.
The use of our Ridges range from developement of numerical
hydrodynamics and n-body codes for use on Crays, to pre- and
post-processing of supercomputer data (including graphics generation),
to the running of large Symbolic Manipulation Programs (i.e. smp), to a
host of smaller problems whose entire life-cycle is spent on a Ridge.