Intel PCM: Getting outgoing QPI traffic information for Westere-EP CPUs using PCM

[Debolay_Tayatiyika]

Dear Intel PCM team,

Thank you very much for your great work on Intel PCM. I have used PCM v1.7 and I just tried out PCM 2.0. I am interested in getting outgoing QPI traffic information. My system has a two-socket motherboard. The sockets are LGA 1366. I use two Intel Xeon E5645 CPUs. PCM 1.7 as well as PCM 2.0 indicate that the CPU model of the Intel Xeon E5645 CPUs is WESTMERE_EP and I see in your implementation that outgoing QPI traffic information is only available for CPU models WESTMERE_EX and NEHALEM_EX. So I have the following questions:

Question 1: What is the reason why you don't export an outgoing-qpi-traffic API for WESTMERE_EP CPUs?

Question 2: Is there anything at all that I can do to get outgoing QPI traffic information from my WESTMERE_EP CPUs using PCM?

Question 3: In the case that it is not possible to get outgoing QPI traffic information from my WESTMERE_EP CPUs (Intel Xeon E5645), which WESTMERE_EX or NEHALEM_EX CPUs can I buy so that I can get outgoing QPI traffic information? Note that the sockets in the motherboard of my system are LGA 1366 and there are only two sockets.

Thank you very much for your time and I will appreciate any help that I can get.

Cheers!

Debolay

[Roman_D_Intel]

Debolay,

thanks for your feedback. The outgoing "data"+"non-data"traffic metric is not supported by Westmere-EP or Nehalem-EP because the underlying hardware does not export events and counters that can reliably deliver such information. Westmere-EX, Nehalem-EX and Sandy Bridge-EP microarchitecturesexposerequired events and counters.

However, the *incoming data* traffic metric supported by PCM can be used tocompute the *outgoing data* traffic. If you consider a QPI link between two processors: the data byte recieved from one end point of a link is sent from the other end point of the link.


Roman

[Debolay_Tayatiyika]

Hi Roman,

Thanks for the answer. I understand that we can compute the QPI outgoing data traffic from one socket to the other like you explained. How about the outgoing data traffic from the sockets towards the IO hubs. For example in my case I have a 2 socket motherboard with two Intel 5520 IO hubs, one IOH for one CPU forming a ring together with the CPUs. How do I compute the QPI outgoing data traffic from a CPU to an IO hub for my Westmere-EP CPUs?

Debolay