Improving the performance of OpenJDK

[Gary Benson]

Gary Benson wrote:
> Gary Benson wrote:
> ...
> > > > > Edward Nevill wrote:
> > > > > > get_native_u2() and get_Java_u2() ... This seems to be a
> > > > > > misguided attempt of the original authors to optimised
> > > > > > reading of halfwords (judging by the comment immediate
> > > > > > preceding the code).
> ...
> > So I did a quick SPECjvm98 run of this change on amd64.  A couple
> > of the times are improved, by 3-10%, but one of the times is
> > *slower* by 11%.  See attached.  I'm not sure what to make of
> > that...
> 
> I'm wondering if rewriting get_Java_u2() to read directly rather
> than read and swap is speeding it up, but removing the optimization
> from get_native_u2() is slowing it down.  I'm going to try this with
> the original get_native_u2() and with get_Java_u2() just a copy of
> the big-endian get_native_u2().

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?

Cheers,
Gary

-- 
http://gbenson.net/