We are developing PCM to monitor QPI traffics. After reading ivy bridge uncore performance guid Chapter 2, section8. QPI Link Layer Performance Monitoring.I have some confusions.
“In addition to generic event counting, each port of the Intel® QPI Link Layer provides two pairs of MATCH/MASK registers that allow a user to filter packet traffic serviced (crossing from an input port to an output port) by the Intel® QPI Link Layer.”
Does that means each port can only counter 1 kind of CTO event(set counter’s control register event select field to 0x38 and match/mask registers to filter packets) at the same time, which means every port’s 4 counter registers can only counter the same CTO event after control register have been programmed.
But some derived events need 2 or more CTO events at the same. How can PCM achieve this?
or we must counter each of these CTO event at different time do the combination after monitoring, if that measure will be imprecise.