Subject: Re: rc5des on NetBSD/vax
To: Dave McGuire <>
From: Brian D Chase <>
List: port-vax
Date: 02/21/1999 13:09:32
On Sun, 21 Feb 1999, Dave McGuire wrote:
> On Sun, 21 Feb 1999, Paul wrote:

> >my vaxstation3100 managed about 1300keys/sec for rc5-64. for comparison, 
> >my diskless 386sx16 machines running linux nfs-root get about
> >5800keys/sec, and (something a bit more recent) my k6-233 manages about
> >390000keys/sec.

>   But...I want to remind folks that, just in case anyone has forgotten,
> that this is about as far from an accurate measure of system performance
> as one can get.  Good rc5 performance depends on certain instructions
> (rotates, if I recall correctly) being supported by the processor in
> question.  Very few processors have these instructions, Intel's and
> PowerPC being the only two common ones that I'm aware of.  VAXen do not
> (also if I recall correctly). 

Oh come now, even if you had no idea if it existed, postulating that the
VAX architecture would be missing any instruction `XYZ' is like playing
Russian roulette with five bullets instead of one.  :-)

Opcode 9C, ROTL - rotate long.  There are also shift instructions for 32
and 64bit operands: ASHL and ASHQ.  I'd guess that with some hand
optimized assembler we'd see better performance.  God only knows what
other VAX instructions could be used or abused into speeding up things. 

Of course, performance will also depend on how the instructions are
microcoded.  Since the shifts and rotates are given 1 byte opcodes, I'm
guessing they were judged as more likely to be used than some of the
extended data instructions which used 2 byte opcodes.  Still, I don't
having any timing info on the different instructions for the different VAX

>   Just a reminder...Yes, most of the VAXen that NetBSD runs on are slow
> ones...but they're not *that* slow.
>   Now, the MicroVAX-I...*that's* slow! ;)

Oh yeah.  I'd love to get mine working on RC5-64.  I think it'd be so very
humourous if the winning key was discovered by a MicroVAX I.  Sure the
odds are in favor of those who can crack the most keys, but there's always
a chance.  It'd be nice to beat out the Intel Pentium speed freaks with
old-fashioned luck. 

Brian "JARAI" Chase | | VAXZilla LIVES!!!