D vs VM-based platforms

Daniel Keep daniel.keep.lists at gmail.com
Tue May 1 16:42:57 PDT 2007



Stephen Waits wrote:
> Daniel Keep wrote:
>>
>> Funny thing, turns out SSE is actually *slower* for doing a dot product
>> than regular old x87 code!
> 
> You should qualify this - I'm guessing you mean for a single dot
> product?  If so, this is the case in most vector coprocessors, as
> load/store overhead can easily outweigh the gains in vectorization.
> 
> --Steve

Sorry; yes, you're right: it's for a single dot product.

I'm surprised at this because of the sheer number of articles I ran
across touting "faster" dot product functions using SSE.  I have a
feeling these people have never bothered to actually *benchmark* their
"faster" functions :P

	-- Daniel

-- 
int getRandomNumber()
{
    return 4; // chosen by fair dice roll.
              // guaranteed to be random.
}

http://xkcd.com/

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