[Mono-list] JVM performance: JVM as a basis for CLR

[Tom]

> most of the information out there in both computer
> classes and trade magazines is that benchmarks 
> _aren't_ useful tests of practical performance

For adversarial benchmarks and the kind of benchmarks
you see in trade magazines that is true.  

For implementors, microbenchmarks are very important,
however, and you can be both Microsoft and Sun are
using them.  Take a look a the 1986 book by Gabriel,
the Smalltalk books, the Self papers, recent work
on Squeak, etc.

The point is not to show conclusively that one
system is uniformly better than another on all
code, it's to understand in what areas (memory
allocation, boxing, multiply-add-fusing, I/O, etc.)
systems  differ.

Another reason to be interested in microbenchmarks
is that in a lot of real code, just one of these is 
usually the bottleneck--you just don't know which.

> I'd guess that a big advantage should be the file
> format.  I don't see how Java classloaders expect 
> to operate that quickly (especially after having
> examined how Java's class reference pools work). 

I think the long-term answer is: through 
caching information and sharing, or possibly a
new, additional, "optimized" format.

Note that a JVM-based implementation of the CLR would,
of course, support both formats.

> To me the biggest reason to look into ORP is because
> it is only a JVM "currently", and was designed to be

> expanded to  support different JITs and
> different instruction sets.

Yes, that and its apparent performance are a good
reason to consider it.  The only disadvantage I
see is that its JIT is written in C++, not Java/C#.
That makes it harder to retarget.  I wonder whether
one could set it up so that new JITs could be added
to it in Java/C#.

> OpenJIT's license isn't GPL compatible.

Yes, too bad.  I wonder whether one could negotiate
something.  There are a bunch more (shuJIT, kissme,
etc.), but ORP looks like the best game in town
for now.

I'll experiment a bit more with ORP.

Tom.






  Intel has even made the
> statement that they
> 
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