Offcore\Uncore events in Intel PCM

[Max_R_]

Hello everybody.

Recently I have started using Intel Performance Counters Monitor tool, version 2.3. As far as i understood, I may cutomize it a bit in order to measure the desired metrics. However, one question appeared:

Does PCM support uncore\offcore events of SandyBridge\IvyBridge processors? (usual ones, not EP) The ones I need are:

• OFFCORE_RESPONSE_0:ANY_DATA:LLC_MISS_LOCAL
• OFFCORE_RESPONSE_0:ANY_RFO:LLC_MISS_LOCAL
• UNC_CBO_CACHE_LOOKUP:STATE_I:ANY
• UNC_ARB_TRK_REQUEST:WRITES
• UNC_ARB_TRK_REQUEST:EVICTIONS

Also, when I launch ./pcm-x it shows "N/A" in the Read / Write columns.

Thanks in advance.

[David_Cherkus]

I've been told that this support requires support from the BIOS, so it may or may not work on a given platform.

This is true for the PCM tool as well as many other tools/libraries that want to get this information.

I've been told the "Romley" Sandy Bridge reference platform does not have such support, and have not been told of plans to add such support.

I can't find the threads that say this, but they are on software.intel.com.

HTH,

Dave

[David_Cherkus]

Some of the threads I was thinking of are:

• http://software.intel.com/en-us/forums/topic/278396
• http://software.intel.com/en-us/forums/topic/329415

Not sure if these map 100% to what you are trying to accomplish...

Dave

[Bernard]

>>>I've been told that this support requires support from the BIOS, so it may or may not work on a given platform>>>

Uncore PMU registers both control and counters can be accessed by kernel mode driver (Windows platform).

[Shailen_Sobhee]

You get N/A for READ/WRITE for the cores because this measurement is not available at the core level, but at the socket level.

[Thomas_W_Intel]

David was referring to the counters for the QPI traffic. Especially on Intel Xeon E5-2600 processors, these counters are often hidden by the BIOS. Please see this article for details.

[Jack_C_]

I am reviewing performance counter these days. I found that the number of counter is less than total events.

I want to know if there is any solution to monitor most of the events. 

Or I only can select 4 or 8 events to monitor.

Thanks

Jack

[Roman_D_Intel]

Jack,

the technique to monitor more events than the number of hardware counters is called "event multiplexing". The performance tool monitors different subsets of events for short periods of time and then extrapolates the event counts to the whole measurement period. This works well for steady state workloads but not for workloads with rapidly changing characteristics. Intel PCM does not support multiplexing but there are other PMU tools that do: for example Intel VTune Amplifier XE.

Roman

[Jack_C_]

Hi Roman,

It's very appreciate. So you mean if I want to monitor more events. I need to re-program counter and event select to monitor another group of events. Right ?

Jack

[Roman_D_Intel]

yes