Vax 11/780 performance vs Sun 4/280 performance

[Brandon S. Allbery]

As quoted from <2282 at rpp386.UUCP> by jfh at rpp386.UUCP (John F. Haugh II):
+---------------
| our plexus p/95 (20MHz 68020, vme bus, 8MB ram, esdi controller) knees at
| about 20 users with a load average of 10+.  on the few occasions the
| machine has been to 13+ it has crashed shortly thereafter.
| 
| the p/55 (12.5MHz 68020, multi bus, 4MB ram, scsi? controller) knees at
| about 10 users.  i don't know the load average off hand but it has been
| up around 10 without crashing.  it just gets painfully slow.
+---------------

The P/55 has a dumb SMD controller, unless you bought the EMSP, which is a
smart SMD controller identical to that used on at least some Sun-3's.

Query:  how did you calculate load average?

Is the P/95 *really* ESDI?  I thought they used a VMEbus Xylogics SMD... but
I don't really know that much about the '95.

4MB RAM is not the best way to run if you have 10 users.  This is from
experience.  You swap *way* too much under SVR2, experience with 2MB on a
386 box with SVR3.1 and 8 heavy database users shows way too much paging.

P/60 with 12.5MHz 68020, multibus, 7MB RAM, EMSP (Xylogics 451 SMD) disk
interface:  ran 18 users at a load average (courtesy my /etc/avenrun) of 2.
[Note that I've never been certain of the reliability of /etc/avenrun as
compared to BSD, since the actual code isn't mine and *definitely* isn't in
the kernel where it should be to be accurate.]  No problems whatsoever; lots
of DBMS, some WP and at least one C compile -- often two concurrent (that
was me ;-) and the system still responded quite well.  Usage has changed
since I left the company that has that configuration; I can check on the
current statistics.  (N.B.  The configuration described above is actually a
P/60 which has been upgraded to a P/75, except for the serial/parallel I/O
controllers.)

As for the 386 box mentioned above:  at 4MB, 8 users all doing database (or
7 users doing database and one compile, again me), it *said* that the kernel
load average was 72.  The "load average" it reports, however, seems to be
not what we usually deoad abverage; you have to divide by the number of
processes, typically 75-80 = load average slightly less than 1.  Performance?
Let's put it this way:  at full load, it was faster than ncoast (68000, 2MB
RAM, dumb SMD controller:  P/35) with *one* user.
-- 
Brandon S. Allbery			  | "Given its constituency, the only
uunet!marque,sun!mandrill}!ncoast!allbery | thing I expect to be "open" about
Delphi: ALLBERY	       MCI Mail: BALLBERY | [the Open Software Foundation] is
comp.sources.misc: ncoast!sources-misc    | its mouth."  --John Gilmore