Bandwidth Microarchitecture Analysis is not collecting data.

[cole_b_]

I am trying to familiarize myself with VTune Amplifier. I am attempting to run the "Bandwidth" test under "Microarchitecture Analysis". When I run it, the summary tab shows the "Elapsed Time" and the "Collection and Platform Info" section, but there is no "Average Bandwidth" section. When I go to the Bottom-up tab, the Bandwidth graph is empty. I assume it is not collecting memory data correctly.

This is running on Ubuntu 14.04 with the Silvermont Celeron J1900 chip. Is it because this cpu is not supported? Or am I misunderstanding what this test is supposed to do. 

Thanks

[David_A_Intel1]

Hi cole:

If the tool is not displaying a warning when you select the analysis type, it should be supported on the processor.

Questions: how long is the "elapsed time" reported by VTune Amplifier?  What version of VTune Amplifier are you using (output of 'amplxe-cl -version')?

[cole_b_]

The version is VTune Amplifier XE 2015 Update 4.1 (Build 412820). The elapsed time is 58.564s with a CPU time of 51.892s. If it matters, the hotspot test works as expected.

[David_A_Intel1]

okay, that release should support what you are trying to do.  However, let's verify that the VTune Amplifier drivers are loaded.  As root/sudo, cd to <install-dir>/sepdk/src and execute the command './insmod-sep3 -q'.

[cole_b_]

I ran the command both as sudo and default user. Both returned:

pax driver is loaded and owned by group "vtune" with file permissions "666".

sep3_15 driver is loaded and owned by group "vtune" with file permissions "666".

vtsspp driver is loaded and owned by group "vtune" with file permissions "666".

[Ekaterina_L_Intel]

Hello Cole B.,

Can you please verify several additional things, it will allow to figure out whether uncore events can be collected or not on your system:

From <vtune install dir>/bin64/ run:

1. >./sep -pmu-types

    You should see "sa" in the output

2. >./sep -el sa

    You should see "UNC_VISA_Memory_DDR_BW" in the outputed list

3. >./sep -start -d 10 -ec "UNC_VISA_Memory_DDR_BW"

     The collection should generate *.tb6 file

4. > ./amplxe-cl -import ./<the tb6 file>

    As result you should see a report with Uncore events collected. Something like below:

Uncore Event summary
--------------------
Hardware Event Type                        Hardware Event Count:Self
-----------------------------------------  -------------------------
UNC_VISA_Memory_DDR_BW.DDR_Chan0_Read32B                          57
UNC_VISA_Memory_DDR_BW.DDR_Chan0_Read64B                     5220544
UNC_VISA_Memory_DDR_BW.DDR_Chan0_Write32B                        234
UNC_VISA_Memory_DDR_BW.DDR_Chan0_Write64B                     822748
UNC_VISA_Memory_DDR_BW.DDR_Chan1_Read32B                           0
UNC_VISA_Memory_DDR_BW.DDR_Chan1_Read64B                           0
UNC_VISA_Memory_DDR_BW.DDR_Chan1_Write32B                          0
UNC_VISA_Memory_DDR_BW.DDR_Chan1_Write64B                          0

Please provide output from each of 1-4 commands below.

Regards, Katya

[cole_b_]

I attached the outputs because the formatting was too weird otherwise. FYI, for step 3 and 4, I had to use sudo for the command to work. Step 4 also produced a lot of the "Cannot locate debugging symbols for file '...'" warnings, but I've read that is normal. It seems I am getting all 0's in the "Hardware Event Count:Self" Column.

[Ekaterina_L_Intel]

Hello,

Can you please make sure your system BIOS is configured to PerfMode as specified in this article:

https://software.intel.com/en-us/articles/SLM-SoC-uncore-performance-monitoring-guide

Enabling uncore monitoring

In order to sample uncore events, the feature must be enabled by BIOS/FW.  Indicators that the FW is not configured for uncore monitoring are:

1. All events counts are zero
2. System agent event counts correctly but all memory controller event counts are zero

On a platform enabled with BIOS menus, there may be a menu option to change "PDM/DFX" setting.  The desired setting is “PerfMode”.  Otherwise you must acquire a FW version with uncore monitoring enabled from your firmware provider.

If your BIOS does expose the PerfMode option, then it will likely be under a "Debug Configuration" menu 

Regards,

Katya

[cole_b_]

It appears that his setting is not available in my BIOS. I likely won't be able to get the right firmware, so I will look elsewhere for this type of benchmarking. Are the other tests that produce results still accurate without this setting? Is it specific to the Memory Bandwidth tests?

[Ekaterina_L_Intel]

Hello Cole B.

It's specific to Memory Bandwidth, as on Silvermont-based platforms it requires uncore monitoring enabled.

Algorithm analsysis and core profiling should work. Let us know if you see other issues.

Regards, Katya