Improving the performance of OpenJDK

[Gary Benson]

Andrew Haley wrote:
> Gary Benson wrote:
> > So this way around it's a little more encouraging; two of the
> > times are 8-10% faster, one is 5% faster.  Some of the times are
> > still slower though, though not by as much, maybe 1-2%.  It's
> > still disturbingly ambiguous though... thoughts?
> 
> Big test runs like SPECjvm98 are too coarse for this kind of thing.

Is there something else I could try instead?  I was thinking about
trying it with DaCapo tomorrow, that's a little more real-world IMO.

> It's petty unbelievable that with the original get_native_u2() and
> the new, definitely faster, get_Java_u2() anything can actually get
> slower.  I'd bet you're looking at noise.  1-2% is vey hard to
> measure reliably on a multi-user system.

True.  I'm just wary of declaring it "definitely faster" if, when
measured, it isn't obviously so.  It may be that the optimization of
doing aligned loads 50% of the time and then swapping is actually
faster than reading the bytes individually...

Cheers,
Gary

-- 
http://gbenson.net/