>> My first guess is the cost
>> of fork/exec operation is handicapped severely.
>
> Here's part of some old lmbench results I had lying around comparing a
> 5000/240 running Ultrix 4.5 vs. NetBSD 1.4.1, as well as a 5000/260 with
> Ultrix 4.5 (it's the 117MHz one).
>      [ ... ]
> Look at the first group - 116,000 us for NetBSD/pmax and 3,500 us for
> Ultrix to fork a process!!  Similar (232,000 vs. 11,000) for exec.

It's astonishing!  So, fork/exec sequence cost in 3.5K+11K for ULTRIX 4.5
while 116K+232K for NetBSD/pmax 1.4.1  Scream!!

> I'll try to get some benchmarks on a 5000/2{4,6}0 running -current unless
> anyone beats me to it.

Please... Besides TLB hardware design differences, pmap.c handles
MIPS1 and MIPS3 in the same algorithm.

Tohru Nishimura