[Openmcl-devel] Fun with Measurements

Brent Fulgham bfulg at pacbell.net
Wed Nov 1 05:51:29 UTC 2006


On Oct 29, 2006, at 5:54 PM, Gary Byers wrote:

> I was going to say that there wasn't likely to be a single smoking  
> gun here; there
> may not be, but this may be pretty close to it.
>
>  - the ppc32 version sometimes goes to great lengths to avoid  
> calculating both
>    the quotient and remainder in things like TRUNCATE when it can  
> tell that only
>    one of them will be used; the 64-bit versions tend to compute  
> both results
>    and one of them is often ignored.
>
> I did a 64-bit version of CCL::%BIGNUM-BIGNUM-GCD that does  
> destructive shifts
> on copies of its arguments; the GCD call above went from 15  
> milliseconds to
> less than 1, and the (COMPUTE-PI-DECIMAL 200) test went from about  
> 1.5 seconds
> to about .12 seconds, so (at least in this case) there seems to  
> have been a
> smoking gun.

Gary,

I reran the benchmarks and posted them to the Wiki page.  What a huge  
difference!

Test						Original 64 bit				Revised 64-bit
=================		=====================	 
==================================
PI-DECIMAL/SMALL          10.49 times					0.47 times.
PI-DECIMAL/BIG			8.13						0.71%
PI-RATIOS				7.79						2.60

Very nice work!

-Brent





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