I'm trying to measure the memory-bandwidth consumed by processes on a dual socket Intel Dunnington with E7450 processors.
To do so I use libpfm to meaure the performance counters. I meaure eventes releated to cycles, instructions or cache misses without problems. However, I have not been able to measure the BUS_TRANS_BURST or BUS_TRANS_MEM events. I tried with the kernel 2.6.29 using libpfm-3.9 and pfmon and with the latests kernel and libpfm4 version but in both cases the memory transaction measures return zero (the other events work fine and I have even measured BUS_TRANS_MEM event using a Inel X3320).
Can anyone imagine whats wrong?
I wonder if the problem may be related to using a dual socket system or if it could be specific of Dunnington processors.