Re: [PATCH] selftests/resctrl: Skip MBM&CMT tests when Intel Sub-NUMA

[Reinette Chatre]

Hi,

On 11/10/2021 12:27 AM, Shaopeng Tan wrote:
> From: "Tan, Shaopeng" <tan.shaopeng@xxxxxxxxxxxxxx>
>
> When the Intel Sub-NUMA Clustering(SNC) feature is enabled,
> the CMT and MBM counters may not be accurate.
> In this case, skip MBM&CMT tests.
>
> Signed-off-by: Shaopeng Tan <tan.shaopeng@xxxxxxxxxxxxxx>
> ---
> Hello,
>
> According to the Intel RDT reference Manual,
> when the sub-numa clustering feature is enabled, the CMT and MBM counters may not be accurate.
> When running CMT tests and MBM tests on Intel processor, the result is "not ok".
> So, fix it to skip the CMT & MBM test When the Intel Sub-NUMA Clustering(SNC) feature is enabled.

It is not clear to me which exact document you refer to but I did find a 
RDT reference manual at the link below that describes the problem you 
mention:
https://www.intel.com/content/dam/develop/external/us/en/documents/180115-intel-rdtcascadelake-serverreferencemanual-806717.pdf

What is not mentioned in your description is that this is a hardware 
errata so the test is expected to fail on these systems and I find that 
disabling the test for all systems based on this hardware errata is too 
drastic.

Reinette