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CPark16
Beginner
184 Views

Cache Allocation Technology - Current specs (allocation granularity, number of CLOS)

Hi, I am interested in testing out the new Intel Cache Allocation Technology. However I have been unable to find the specifications of CAT functionality provided by the 6 processors. I would like to know beforehand, the capabilities of each processor before purchasing the processors, and I would be grateful if anyone could help.

The CAT supporting processors are: E5-2608L-V3    E5-2618L-V3    E5-2628L-V3    E5-2648L-V3    E5-2658-V3    E5-2658A-V3

I would like to know the CBM_LENGTH (the granularity of cache allocation), and the COS_MAX (Maximum number of classes which can make use of different allocations)

I found how to read the values for the two values in "64 ia32 architectures software developer manual" Section 17.16.2.2

It would be great if Intel could publish the values so that potential buyers could know the capabilities of each processors, however I couldn't find any information, and thus I'm leaving a post in the forum.

Thank you.

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5 Replies
Patrick_F_Intel1
Employee
184 Views

Hello Chang,

As Bill Clinton used to say "I feel your pain".. that is I sympathize with the difficulty customers have trying to figure this out.

I have data for one 'Intel(R) Xeon(R) CPU E5-2699 v3 @ 2.30GHz' system and it didn't support these CAT feature but I don't know if the feature was just disabled in the bios. That is, cpuid.(eax=07h, ecx=0h).ebx[15] == 0 which indicates (according to jan 2015, SDM vol 3, section 17.15.2.1 Enumeration and Detection Support of Cache Allocation Technology) that CAT is supported.

I'll ask some other folks at Intel.

Pat

CPark16
Beginner
184 Views

Pat, Thanks for checking on that machine!
But, I don't see the 2699 v3 as CAT supporting machine. I wonder why the cpuid indicates that CAT is supported.... weird....

I'd be excited to hear from anyone who can help! 

Thanks again Pat!

Patrick_F_Intel1
Employee
184 Views

I meant to say:

That is, cpuid.(eax=07h, ecx=0h).ebx[15] == 0 which indicates (according to jan 2015, SDM vol 3, section 17.15.2.1 Enumeration and Detection Support of Cache Allocation Technology) that CAT is NOT supported.

 

CPark16
Beginner
184 Views

Okay! that makes more sense :D
Intel states that only the 

E5-2608L-V3    E5-2618L-V3    E5-2628L-V3    E5-2648L-V3    E5-2658-V3    E5-2658A-v3 

processors provide CAT

 

Andrew_H_Intel3
Employee
184 Views

Hi Folks,

Old post I know, but hoping to clarify -- CPUID can be used to detect the presence of the architectural version of the Cache Allocation Technology (CAT) feature. In particular, once cpuid.(eax=07h, ecx=0h).ebx[15] == 1 (at least one allocation technology supported on the processor) has been verified, then CPUID leaf 0x10 and sub-leaves provide further details on the CAT feature such as mask lengths available.

An easier way to enumerate the capabilities is via the 01.org RDT utility linked here:

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

This utility provides not just simplified enumeration but also a Top-like interface to use the monitoring and control features (CMT, CAT, MBM, CDP,...)

Also... on support.... CAT is now architecturally supported on Xeon -- all models of the Intel(R) Xeon(TM) E5/E7 v4 Family of Server Processors (or newer) support CAT. On previous models (v3) support was only present on a subset of specialized SKUs (such as communications SKUs), and without CPUID support.

CAT is part of Intel's Resource Director Technology (RDT) feature set. Lots more details linked from the main RDT landing page here:

http://www.intel.com/content/www/us/en/architecture-and-technology/resource-director-technology.html

Thanks,

~Andrew