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From "Mikhail Fursov" <mike.fur...@gmail.com>
Subject Re: [drlvm] Class unloading support
Date Thu, 26 Oct 2006 07:08:47 GMT
Egor,
I would rather disagree in most of the details. :(

1) "1/10 of the whole heap is probably very much :)"

No. You can't measure performance in method/class numbers and proportions at
all. It's normal situation when only 1% of methods consume 90% of CPU ticks.
Not all of them depends on devirtualization or classes unloaded. So you
can't say that 1 class unloaded is OK but 100% is bad. It's a lottery.

2)  "hm, keeping VTable pointers on operands (and reporting them in root
sets) solves the problem. That slightly increases register pressure,
but I think is a better solution than pinning VTables (and rather
straightforward)."

The  Alexey's solution does not affect devirtualizer at all. Unpinning
vtables you have to include them into enumeration. I'm not sure that moving
vtables to opnds as object-type is a simple task and think that it l will
affect GC-enumeration part in JIT too.
Another cons: type profiling we will have soon. You have to include it into
enumeration.




-- 
Mikhail Fursov

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