[vsipl++] [patch] New benchmark - vector division

[Jules Bergmann]

Don McCoy wrote:
> Here is a new benchmark for testing element-wise vector division.  Also 
> attached are two performance graphs comparing multiplication and 
> division - one shows mega flops per second and the other latency, or the 
> number of microseconds per operation.

Don, This looks good, please check in in. -- Jules
> 
> The graph showing flops per second is somewhat misleading for two 
> reasons: both divide and multiply for real numbers are each counted as a 
> "flop" even though they take a different number of clock cycles to 
> perform.

It does answer the question of whether a division FLOP is really the 
same as a multiply FLOP.  Depending on problem size, it looks like 1 div 
FLOP ~ 8 mul FLOPS.

>  Second, complex-complex division takes more operations (11, 
> two of which are real-real divisions) than complex-complex 
> multiplication (6).  This gives them a comparable flop count, even 
> though the division takes roughly twice as long.

Comparing complex-multiply MFLOPS vs complex-division MFLOPS is somewhat 
of an apples to oranges comparison.  The latency numbers, or 
alternatively measuring points per second, are a good way to look at it.

What machine/configuration are the results from?

				-- Jules


-- 
Jules Bergmann
CodeSourcery
jules at codesourcery.com
(650) 331-3385 x705