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From "Eugene Ostrovsky" <eugene.s.ostrov...@gmail.com>
Subject Re: [drlvm][jvmti] Profiling support - Compiled Method Load event
Date Fri, 10 Nov 2006 12:06:07 GMT
Hello All.

One more "hole" in current JVMTI Profiling implementation is Compiled Method
Load event.

Current VM doesn't report this event for methods that are inlined by JIT.
Though spec requires it to be sent for every compiled method:
http://java.sun.com/j2se/1.5.0/docs/guide/jvmti/jvmti.html#CompiledMethodLoad

To support the feature VM need to know about those inlined methods. Right
now I can see two possible approaches:

1. When VM initiates method compilation, it can ask the jit about methods
that were inlined to compiled method and report all of them.
2. JIT itself can notify VM about every compiled method by calling some
special interface function after the method compilation.

I'm not sure about which approach is better.
Each of them requires additional interface function (1.- to JIT from VM; 2.
- from VM to JIT).

The second approach seems to be more complicated in terms of VM - JIT
interaction. I mean that the following scheme "VM calls JIT's function to
compile method. -> JIT's function in it's turn calls VM's function to notify
about compiled methods. -> VM's function dispatches the event to TI
agents..." introduces additional level of complexity than if "VM calls JIT's
function to compile method. VM asks JIT about inlined methods. VM dispatches
event to TI agents."

Ideas & suggestions are welcome.

Thanks,
Eugene.

On 10/24/06, Eugene Ostrovsky <eugene.s.ostrovsky@gmail.com> wrote:
>
> Hi all.
>
> It seems that we have most of JVMTI implemented in drlvm. Still some of
> profiling support features is left.
> I'm going to take a look on "VM Object Allocation" event.
> I'll try to come up with design tomorrow.
>
> Thanks,
> Eugene.
>
>

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