Re: need to focus on java performance?

[Bryce McKinlay <mckinlay at redhat dot com>]

Tom Tromey wrote:
> Bryce> Finding the method's address is easy enough, but what about the
> Bryce> address of the atable entry containing the pointer to the method?
> Bryce> Thats what needs to be patched. Also, patching all the callers for a
> Bryce> given class at once would mean we can drop all the unneeded
> Bryce> trampolines, saving memory.
>
> Well, one idea would be to put the address of the atable into the
> trampoline itself.  The trampoline function could initialize the
> class, rewrite the atable entry, and then forward the call.  (This is
> more or less what my jit does.)
>   
The problem is that there can be many different atables all pointing to 
a single trampoline/function (and the list can grow as new 
classes/atables are linked). I suppose you could create a unique 
trampoline for each & every atable entry, but that seems a bit wasteful.

> I don't want to stop idea generation, of course.  And debating it and
> whatnot is fine.  At the same time, often these threads generate a lot
> of discussion and no concrete results.  I'd like someone to volunteer
> to make a wiki page describing the various optimization ideas and
> implementation approaches.
>   

Yeah, good idea. Didn't we once have something like this?

Bryce