[LLVMdev] Questions about LLVM PGO and autoFDO

[猫妖]

On Tue, May 13, 2014 at 1:15 PM, 猫妖 <spcatman at qq.com> wrote:

   2. 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.
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