[Mono-list] Need some short answers on the new Mono JIT / Mini

Paolo Molaro lupus@ximian.com
Wed, 28 May 2003 10:17:41 +0200

On 05/27/03 Tom Fransen wrote:
> - My first question is: were can I find the document on mini that is
> mentioned in the release notes???
> I searched the Mono TAR files but I cannot find it. I don't know if it is
> stored in CVS.
> I have no experience with CVS , who can help me out here?

The files are in cvs, will add them to the tarball for next release.

> - If I start a program I can use the option -O=all to enable all
> optimizations.
> Which optimizations are used when I do not use the -O option, what are the
> default optimizations ???

The default optimizations may change over time as we add more
optimizations and as we consider them stable enough. Optimizations that
are costly to perform may not enter into the default set, though:
maybe some student will be interested in doing some profile-directed
recompilation of methods... :-)
The default optimizations also depend on the processor in the system
where you run the JIT.
If you want to set some defined optimizations, you can use:


The '-all' part will disable all the default optimizations.

> - I assume that the mono JIT compiles the code on a method basis (like MS
> JIT).


> However if I use the -O=all option the difference in duration between the
> first
> and the second invocation is almost zero!!
> So in other words there is no initial cost for the JIT.
> Can anybody explain why this is???????????

My guess is that the method you used to measure the time is incorrect or
not precise enough to give reliable results:-)


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