#2 UNHALTED_REFERENCE_CYCLES returns 0 on Ivy Bridge cpus

open-invalid
nobody
None
5
2013-03-06
2013-03-01
No

Hello,

I am porting an application to Ivy Bridge architectures using UNHALTED_REFERENCE_CYCLES. This counter works well on Sandy Bridge, but returns 0 on Ivy Bridge. I tried the provided ./example/syst_count example and the counter returns 0 as well. I am running the libpfm-4.3.0, Linux Debian Squeeze kernel 3.2.0, and I have attached a copy of my /proc/cpuinfo.

I believe Likwid 3.0 does support this counter (named CPU_CLOCK_UNHALTED_REF_P:PMC1).

Thank you for your time,

Jean-Philippe

Discussion

  • Jean-Philippe HALIMI

    I just wanted to add that I have tested both the 4.3.0 release and the latest git version (commit 5ebbf987f586c6bd7521ab338865f6c5c32fa964) and both versions have the problem

     
  • Jean-Philippe HALIMI

    Ok I figured out the problem did not come from the libpfm itself but from the Linux perf lib that was not up-to-date. The kernel 3.2 is too old to use it.

     
  • Jean-Philippe HALIMI

    • status: open --> open-invalid
     

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