Path: utzoo!dciem!nrcaer!scs!spl1!laidbak!att!osu-cis!killer!vector!rpp386!jfh
From: jfh@rpp386.UUCP (John F. Haugh II)
Newsgroups: comp.unix.wizards
Subject: Re: Vax 11/780 performance vs Sun 4/280 performance
Message-ID: <2282@rpp386.UUCP>
Date: 1 Jun 88 18:13:41 GMT
Article-I.D.: rpp386.2282
References: <14968@brl-adm.ARPA> <601@modular.UUCP> <7331@swan.ulowell.edu>
Reply-To: jfh@rpp386.UUCP (The Beach Bum)
Organization: Big "D" Home for Wayward Hackers
Lines: 31

In article <7331@swan.ulowell.edu> arosen@hawk.ulowell.edu (MFHorn) writes:
>In article <601@modular.UUCP> olson@modular.UUCP (Jon Olson) writes:
>> there is a knee in the performance curve of the Sun-4/280 at > 15 processes
>> And the Sun-3's are no better: the knee there is >7 processes.
>
>Some time ago I saw a Sun 3/280 with a load average of 17+.  There were
>17 'extra' jobs running.  I don't know what they were doing (they weren't
>mine), but there was no [noticable] degradation in response time at all.

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.

i suggest the Big Problem is with the disk/controller combinations.  my
'386 can't run an expire and an rn together because the disk saturates.
same seems to be true with the plexus machines.  the p/55 has a single
controller and a single drive.  the p/95 has a single (faster) controller
with two drives.  once the i/o on either plexus is saturated (the famous
popcorn noise is my general working definition), regardless of the number
of processes, adding one more serious dogs the system.

- john.
-- 
John F. Haugh II                 | "If you aren't part of the solution,
River Parishes Programming       |  you are part of the precipitate."
UUCP:   ihnp4!killer!rpp386!jfh  | 		-- long since forgot who
DOMAIN: jfh@rpp386.uucp          |