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Re: Java VM specifics on MacOSX

There's a bit more to the 'server' VM than that. A quote from
http://java.sun.com/products/hotspot/docs/whitepaper/Java_Hotspot_v1.4.1/Java_HSpot_WP_v1.4.1_1002_4.html

"The server compiler is tuned for the performance profile of typical server
applications. The Java HotSpot Server Compiler is a high-end fully
optimizing compiler. It uses an advanced static single assignment
(SSA)-based IR for optimizations. The optimizer performs all the classic
optimizations, including dead code elimination, loop invariant hoisting,
common subexpression elimination, and constant propagation. It also features
optimizations more specific to Java technology, such as null-check and
range-check elimination. The register allocator is a global graph coloring
allocator and makes full use of large register sets that are commonly found
in RISC microprocessors. The compiler is highly portable, relying on a
machine description file to describe all aspects of the target hardware.
While the compiler is slow by JIT standards, it is still much faster than
conventional optimizing compilers. And the improved code quality pays back
the compile time by reducing execution times for compiled code. The server
compiler performs full inlining and full deoptimization."

Not mentioned is instruction scheduling, which would benefit the G5 greatly.

What *is* mentioned is: "The compiler is highly portable, relying on a
machine description file to describe all aspects of the target hardware", so
as far as I can see Apple have no technical reason not to be able to
*easily* implement the server VM. Odd then that there isn't one available?

Andy.

----- Original Message -----
From: "Michael Hall" <email@hidden>
To: "John W. Whitworth" <email@hidden>
Cc: "Java-Dev" <email@hidden>
Sent: Saturday, April 24, 2004 5:05 PM
Subject: Re: Java VM specifics on MacOSX


> On Saturday, April 24, 2004, at 09:20 AM, John W. Whitworth wrote:
>
> > The whole point of the VM IS that it's platform/ hardware optimised.
> > You see the benefits of the server VM after seconds, not days, as
> > pointed out above The server VM does much more aggressive inlining and
> > this is what makes the difference. You can control the size of methods
> > that are inlined via a JVM option.
> >
> If you are specifically interested in how inlining is setup on OS/X
> there was a thread a while back where Greg Parker indicated some of the
> details. Should be in the archives. That was kicked off a computational
> performance list thread where inlining was one of the concerns if I
> remember right.
> 'inlining' would probably be a good enough keyword to check the
> archives on and you would most likely want to check out what Greg had
> to say on it.
>
> Mike Hall <mikehall at spacestar dot net>
> <http://www.spacestar.net/users/mikehall>
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References: 
 >Re: Java VM specifics on MacOSX (From: Michael Hall <email@hidden>)



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