Re: [perfmon2] Intel Nehalem : OFFCORE_RESPONSE_0 event Implementation

[Vince W. <vwe...@ee...>]

On Fri, 9 Jul 2010, Ankush Gupta wrote:

> Hi,
> 
> 
> I am interested in measuring per-core remote read memory bandwidth on an Intel Nehalem machine
> using libpfm4. 
> 
> I think the only way to do it is using the OFFCORE_RESPONSE_0 event. Looking at the source
> code of libpfm4:  intel_nhm_events.h, the event is commented out. The encoder for the function
> pfm_nhm_offcore_encode in file ./pfmlib_intel_nhm.c has also been commented out. Seems it is
> not supported yet.
> 
> Is this a limitation of libpfm4 or perf_events?

>From what I understand, using OFFCORE_RESPONSE requires access to an 
additional processor MSR (one not used by other counters) and that 
perf_events currently does not support this.

Vince