[RC5] PowerPC RS64III

Peter Cordes peter at llama.nslug.ns.ca
Fri Dec 8 02:15:53 EST 2000


On Wed, Dec 06, 2000 at 04:20:47PM +0100, stvernaillen at ge.cokecce.com wrote:
> 
> All,
> I tried the AIX client out on an IBM rs6000 H80 with 2 PowerPC RS64III
> processors thinking I'd see some nice results....( XXXXX)
> what did i get :[5,328 keys/sec] per processor on rc5.
> I compared it with an H70 with 4 PowerPC RS64II and it comes up with [934,463
> keys/sec] which seems a lot better. (YYYYY)
> On OGR this does not seem to happen
> PowerPC RS64III : [2,562,456 nodes/sec]
> PowerPC RS64II  : [1,937,939 nodes/sec]
> I know the client is a beta version. but i tried with the offical one and got
> the same results.
> 
> Does anybody else experience this?

 I seem to remember that some version of rc5des (way back then) ran really
slow on the school computer.  A later version of dnetc seemed to work OK,
though.  Apparently, running about 4 processes of it made AIX run slow (on a
6 CPU RS/6000 that is mostly loaded with hundreds of people checking their
email and running lynx).  The admin asked me to stop, and I did since it
wasn't worth the trouble to investigate.  (The machine doesn't have a very
nice devel environment, since that's not what its for. I would have had to
install a lot of stuff, etc.)

 Take this with a grain of salt, since I'm not sure about all that.  I wish
I had the hardware to have experienced this :)

> Is there that much difference between the two processors?

 They probably implement different supersets of the PowerPC instruction set
architecture.  Check chips.ibm.com or something.  My guess is that on the
RS64III, the processor doesn't support one of the instructions that the RC5
core uses, but the RS64II does.  The instruction might be getting emulated
in software, which is why it still runs at all, instead of getting a SIGILL.
Emulation is really, really slow.

-- 
#define X(x,y) x##y
Peter Cordes ;  e-mail: X(peter at llama.nslug. , ns.ca)

"The gods confound the man who first found out how to distinguish the hours!
 Confound him, too, who in this place set up a sundial, to cut and hack
 my day so wretchedly into small pieces!" -- Plautus, 200 BCE
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