RFR: 8254723: add diagnostic command to write Linux perf map file [v2]

[Yasumasa Suenaga]

On Wed, 21 Oct 2020 09:09:49 GMT, Nick Gasson <ngasson at openjdk.org> wrote:

> Yes that sounds like a good idea. Add a (diagnostic?) option `-XX:+WritePerfMapOnExit`?

I think we should use this option carefully because nmethod might be unloaded. So we should use this with `-XX:-UseCodeCacheFlushing`.

BTW we can use `Compiler.codelist` dcmd for this purpose now. If you implement `WritePerfMapOnExit`, we should consider code cache flushing and should use `Compiler.codelist` in some case. I've published perfmap generator from `Compiler.codelist` https://github.com/YaSuenag/saperf

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PR: https://git.openjdk.java.net/jdk/pull/760