[rc5] Solaris client slow?

Henry W Miller mill0440 at gold.tc.umn.edu
Fri Jun 13 08:09:28 EDT 1997

On Thu, 12 Jun 1997, Trey Valenta wrote:

> Appologies is this is already been touched on, but my client seems to be
> awfully slow. I am running Solaris 2.5.1 on a 100MHz Sparc 20 and my
> dinky win95 box (486/66 with about no RAM).
> My Sparc is doing about 67000 keys per second at most. It's of course
> slower at times but for the most part the load is normally low. My Win95
> box does about 44000 keys/s. It's load is null as this only exists for
> cc:Mail (i.e. Devil's work).

looks about right for a sparc to me.

> Other machines I've checked on are reporting these numbers....


> I know a P166 is a nice little machine, but is it really 2-3x faster
> than the sparc20? Any comments or clues?

It is for RC5.  When an engineer decides to build a CPU there are 
trillions of instructions they can potentially put into the chip.  
However it has been mathamatically proven that with a single instruction 
cpu (subtract, branch on zero) you can mathimatically emulate every one 
of those trillion instructions!  

When the engineers at Sun decided to make the sparc CPU they decided that 
a ROL instruction is rarely used, so instead of a ROL instruction they 
put in a different instruction that is used more often.  The inscrutions 
they did put in are very fast, the instructions are just emulated with 
several insctructions.

The engineers at Intel put the ROL insctruction into their CPU.

The RC5 algrythm spends most of it's time doing ROL insctructions.  
Therefore for RC5 your p166 is a very good chip while your Sparc is 
aweful.  If instead of RC5 you were doing somethign else the Sparc would 
probably be better.

Problmes like this is why computer science people call benchmarks that 
marketing likes to quote worthless.  I've even heard MIPS called 
meaningless indecator of processors suckiness.  And similer things for 
spec and MFLOPS.  

You need to comare a comptuers AFTER they are running optimised versions 
of the program you want to run on them.  In general your sparc will come 
up better then an intel chip, but there are exceptions.
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