[PCM] QPI traffic estimation - stopped functioning

Andrew_M_ — Thu, 29 Dec 2016 20:31:35 GMT

I'm using PCM to measure QPI traffic on a NUMA server running Linux, but PCM unexpectedly stopped displaying QPI traffic.

In the past, I have run pcm.x to get human readable data, and it worked.

I needed to access the QPI traffic programmatically, so I tried using PCM's C++ interface.
My code containing a few PCM member functions worked up until PCM::QPILinkSpeed() was called. Then the code exits without throwing an exception and prints 'Segmentation Fault' to cerr.

Since that moment, pcm.x no longer shows QPI traffic. (Symptoms are similar to this thread: https://software.intel.com/en-us/forums/software-tuning-performance-optimization-platform-monitoring/topic/473955 )

The attached file shows the output from running pcm.x

pcmOutput.txt

I see the message mmap failed: errno is 1
This surprised me because I am running pcm.x as root.
My BIOS settings were not changed.

Here are my environment details:

CPU
- 2x Xenon E5-2643 V3
Motherboard
- Dell 0599V5 Version A12
BIOS
- Dell Version 2.0.1
Distro
- Fedora 24 (Workstation Edition)

I've tried restarting, cleaning the PCM directory and re-building, but no luck.

Would anyone be able to give me a pointer to explain what may have gone wrong, and a nudge in the right direction towards fixing pcm?

Thanks for your attention,
-Andrew

Hi Andrew,

Roman_D_Intel — Thu, 05 Jan 2017 14:24:07 GMT

Hi Andrew,

It would be helpful to see the call stack of the crash (use gdb to display it). Could you try to follow these steps to repair environment after the crash?

Thanks,

Roman

Hi Roman,

Andrew_M_ — Fri, 06 Jan 2017 01:25:05 GMT

Hi Roman,

Turns out I wasn't using the most recent version of pcm :) Updating solved my problem.

Thanks for the advice though.

-Andy

topic Hi Roman, in Software Tuning, Performance Optimization & Platform Monitoring

[PCM] QPI traffic estimation - stopped functioning

Hi Andrew,

Hi Roman,