RFR: 8317453: NMT: Performance benchmarks are needed to measure speed and memory [v5]

[Gerard Ziemski]

On Mon, 20 Jan 2025 01:56:12 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> We check for the flags when we initialize NMT and run only when NMTBenchmarkRecordedPID is set.
>
> We do have some terminal flags like `-version` and `-Xshare:dump`, but generally the VM does not have magic flags that behave that way. I still don't have a clear picture of the different phases involved with this work. We have a recording phase. Then we have the benchmarking phase that does something (I can't figure out what) with the recording. Then we have the Java tool which does ... what?
> 
> In any case I have concerns about how the "benchmarking" is initiated.

The problem is I want to record every os::malloc(), so I need locks way before they are initialized in the VM.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23115#discussion_r1925547655