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From Stefano Mazzocchi <stef...@apache.org>
Subject Re: performance of drlvm
Date Thu, 27 Jul 2006 16:41:13 GMT
zouqiong wrote:
> I am very happy to know a person who has a common goal with me :-)
> en, my research focus on how to get more useful information to guide
> compile
> thread
> and garbage collector to optimize the data locality and code quality,
> and my
> interest
> is how to use performance monitor to get profile , and i think few vitural
> machine use the performance monitor to guide code optimization
> automatic. Of
> course, many paper
> use PMU to guide the analysis.

There is one interesting trick that I learned at an IBM presentation
that was done at MIT last year (apologies, I don't remember the name of
the speaker) about the trick of "persisting" the runtime optimization
information that the JVM discovers after the first few runs of a
particular program.

For server side software, the warm-up time is not a big deal, but for
client side software, it's a huge deal if Eclipse (or your, ehm, firefox
extension written in java <grin>) starts up in 0.5 seconds instead of 5.

The idea, basically, is that the *very first* time an application is
run, the JVM will profile it and optimize the bytecode -> native
compilation and go on doing its normal hot-spot stuff... but then every
now and then, or at shutdown, the JVM will write that info on disk, so
that it will be possible for the *next* run to start with a
"optimization profile" that is, so-to-speak, precompiled and doesn't
have to be inferred from the runtime execution of the program.

There are some issues with the approach, but I think it's a great idea
and nothing that we, as a community, can't find an answer for.

BTW, would be great to have those people here talking to us about those
new JVM tricks they are doing in IBM for J9.


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