Questions about LLVM PGO and autoFDO

  1. Problems in autoFDO:
    Actually the problem happened in using create_llvm_prof, transformation is
    failed.
    clang -O2 -g test.c -o a.out
    perf record -b ./a.out (perf version is 0.0.2, “-b” option is not recognized, why?)

Hm, now I noticed the perf version you are using. That’s too old. You
will need perf and kernel newer than 3.4. I’m currently using
3.8.13.13

Diego.

Yes, my perf is so old. It would bring errors like:Read wrong magic,(because
“PERFFILE” has been changed to “PERFILE2”) and others.

And I have updated my perf to about version 3.4, which already support “-b”
option, but still convert failed. (I didn’t add “-b” option because my linux OS
is version2.6, lower than 3.4. Meaning no Last Branch Records samples.UserGuide
said LBR is not prerequisite. I don’t know whether it is the reason for convert failure,
or it is because of different perfdata format from different perf version. )

I will try the newest perf you recommended.