FR docs: outline how to handle perf.data from different machines

[GitMensch]

Is your feature request related to a problem? Please describe.
For some reasons I don't get it working...

Describe the solution you'd like
Clear docs how to go on with the archive (so first perf record, then perf archive, then bringing both to the target, then extracting the tar.bz2 to ~/.debug (can it be a different path?) then running hotspot
-> raises "PerfUnwind::MissingElfFile: Could not find ELF file for /some/file.so. This can break stack unwinding and lead to missing symbols." messages, no matter if --debugPaths is set to $HOME/.debug or not.

I guess that will work for both --exportTo and for "Show disassembly".

Additional context
The files are not archived as their original paths but using their buildid and a split, so instead of
/some/file.so
we have
~ /.debug/some/file.so/720520c3602932517725441cb80ec07c162046fa/elf

Version used: last CI that ran on RHEL8.

[milianw]

the format with the buildid sounds correct. have you checked with e.g. strace -e file where perfparser is looking for the files?

[GitMensch]

Not yet - also because I was not 100% sure (and did not found that in the docs either) how to correctly manually execute hotspot-perfparser (please add it or specify here, thanks).