Exploring JRuby performance on HotSpot?

[Charles Oliver Nutter]

Who would be the best person to talk to about our efforts to take JRuby 
performance to the next level? I've run into some peculiarities.

Most recently, I modified our dynamic call path to make it possible for 
Hotspot to inline across dyncalls. While it seems to help some 
benchmarks, it hurts others, and it only seems to help when we remove a 
bunch of other logic. I have not been able to determine why it degrades 
anything, since it should allow more code to inline and ultimately 
reduce call overhead.

I've been looking at OptoAssembly output and things look ok to me, but 
I'm not sure I know what I'm looking at. I can definitely see that CALL 
operations are largely eliminated.

Anyone interested in a little JRuby optimzation adventure? I can provide 
a binary snapshot and simple instructions to reproduce any of these 
benchmarks.

- Charlie