[SunRescue] Speed of SS10 vs DEC 3000/300LX Alpha?

[Eric Johnson]

On Tuesday 17 April 2001 18:43, you wrote:
> > You didn't cite memory, though I suspect that would not be important if
> > disk writing or ethernet are where the bottleneck on the Alpha lies.
>
> Both have 64mb ram.  It took 2hrs to do the SS10 360mb tree and just under
> 4 hrs for the Alpha 125mhz identical tree.  I am very impressed with the
> SS10.

It's possible that the problem comes from the design of the Alpha 21064/66 
chip. The original Alpha design did not have any native 32-bit commands so it 
suffered HUGE performance penalties on non-64 bit commands and on mis-aligned 
data. 

Also, the 125 MHz Alpha was the second slowest ever produced (IIRC). Sun and 
DEC went different directions with RISC; DEC designs were to strip down the 
command set to maximize absolute clock speed, thus the Alpha at 125 MHz was 
slower (at integer ops anyway) than an x86 of the same speed. Where Alphas 
scored was that at a time when the fastest x86 was a Pentium Pro, you could 
get 433-533 MHz Alpha systems. (Note that an Alpha can match or outperform an 
x86 of the same speed at FP operations even now, it just wasn't designed to 
be a star at integer work.)

If you add those effects together, it's not terribly surprising that an SS10 
would outperform an Alpha of that age. (ignoring the effects of bus design)

-- 
-- Eric Johnson