Cache Allocation Technology on Xeon E5 2608L v3

[Haishan_Z_]

Hi all,

I am having trouble with Cache Allocation Technology (CAT) on Xeon E5 2608L v3. According to various documents CAT is supported on this chip, but when I check the availability using CPUID(07, 0), result suggests that CAT is not available.

I am using the CPUID primitive from PCM 2.8, which successfully detected the availability of CMT. I did the test in Ubuntu 14.04. The motherboard used is Asus X99-A. Turboboost and SMT are disabled during the test.

Any help is greatly appreciated!

[Andrew_H_Intel3 · Accepted solution]

Hi Haishan,

You're correct that the Intel Xeon E5-2608L v3 processor supports model-specific Cache Allocation Technology (CAT), as verified on the main landing page for these technologies:

• Cache Monitoring and Cache Allocation Technology Landing page, which contains Product Briefs, links to software tools and support and CMT/CAT related blogs: https://www-ssl.intel.com/content/www/us/en/communications/cache-monitoring-cache-allocation-technologies.html

On the Xeon E5 v3 family of server processors CAT is supported on a subset of SKUs, and is model-specific, meaning that CPUID enumeration of the feature is not included, however the MSR interfaces are very similar to the architectural interfaces documented in the Intel Software Developer's Manual . Further documentation on the differences between architectural and model-specific versions is available upon request.

On some platforms you may need a BIOS update to ensure the latest support.

[Maria_M_]

Hi all,

i downloaded and compiled  CMT, MBM and CAT reference code. I run pqos, CMT and CAT on a platform that has two Xeon E5-2658A v3 processor.

When i run "pqos -s -v" program a message notifies that CAT feature cannot be detected using CPUID.0x7.0 and further the following message is displayed:

"ERROR: RDMSR failed for reg[0xc90] on lcore 0".

I checked CAT availability using CPUID(EAX=0x7, ECX=0x0) it returns value 0x37ab (bit 15 =0 meaning CAT is not supported).

CMT example (monitor_cpp) runs fine.

According to Intel documentation, no changes in OS or kernel are needed to run the reference code.

Any help would be appreciated to understand why the processor does not seem to support CAT when it is supposed to.

Thanks in advance,

Maria. 

[Omar_A_]

Hello,

I have a similar problem. I have a E5-2648L v3 Engineering Sample processor and I can't get CAT to work. I have installed msr-tools and probed 0xc91, but i get an error stating that it could not retrieve such value from CPU 0. The processor I have is an engineering sample and my question is whether the processor doesn't support CAT because it is a ES or if the intel documentation found below is incorrect.

https://github.com/01org/intel-cmt-cat

Thanks,

Omar

[Andrew_H_Intel3]

Hi Omar, Maria,

Please ensure that the latest BIOS is installed for your platform to ensure proper access to the CAT MSRs.

As noted above, the CAT implementation on certain SKUs of the Xeon(tm) E5 v3 family of server processors is model-specific, meaning that CPUID support is not included, however in supported SKUs the MSR interface will work as usual. Supported SKUs are listed here:

https://www-ssl.intel.com/content/www/us/en/communications/cache-monitoring-cache-allocation-technologies.html

Please also ensure that you are using the latest version of the PQoS utility from 01.org as hosted on GitHub.

If you are using a supported SKU but not able to access the MSRs then it is likely that your platform BIOS is out of date.

Thanks,

~Andrew

[Omar_A_]

Hi Andrew,

Thanks for following up. Here is my current setup:

Motherboard: ASrock EPC612D4I

Bios Version: 1.2 (latest see, http://www.asrockrack.com/general/productdetail.asp?Model=EPC612D4I#Download)

CPU: E5-2648L v3

I have attached few screenshot to show the error I am getting. I have the latest version of the intel-cmt-cat tool found on 01org.