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The JVM is not a tracing JIT compiler. Tracing is a very slow operation. Hence the warmup problem is substantially worse for tracing JITs.

I saw figures for warmup in tracing JITs that were so hillariously bad, that I thought they must be a typo.

People I know are currently writing a paper on this subject. I hope it will come out in the next 2 or 3 months. That should put our discussion, and the warmup performance of tracing JITs, on a firmer basis.




> The JVM is not a tracing JIT compiler

He didn't claim or imply it was.

> Tracing is a very slow operation.

Wait a second - you were just saying that PE was slow. Now you are saying that tracing is slow instead?

> Hence the warmup problem is substantially worse for tracing JITs.

This is contrary to everything I've seen in the research. Tracing JITs like LuaJIT and PyPY as fast to warm up compared to method JITs and PEs.


I said, or was trying to say that DPE and tracing have bad warmup.

    Tracing JITs like LuaJIT and PyPY as fast to warm up compared to method JITs and PEs.
I have heard the opposite about PyPy, which is meta-tracing.

I'm a bit uncomfortable with saying "I have heard ..." As far as I'm aware there is no actual published research on this question. But there will soon be, so I would like to withdraw from this debate until I have read that research.




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