Re: Question about the CAT and CMT in Xen

[Chao Peng <chao.p.peng@linux.intel.com>]

On Mon, Aug 31, 2015 at 04:09:31PM -0400, Meng Xu wrote:
> I looked into the xen/arch/x86/psr.c and found that the function
> cat_cpu_init() just returned without initializing the variable
> "cat_socket_enable".
> 
> Both  !cpu_has(c, X86_FEATURE_CAT) and c->cpuid_level <
> PSR_CPUID_LEVEL_CAT are evaluated as 1 inside the function
> cat_cpu_init().
> 
> OK. I understand that  the cpuid info shows that the CPU does not
> support CAT. However, according to the table at
> http://www.intel.com/content/www/us/en/communications/cache-monitoring-cache-allocation-technologies.html,
>  Intel(R) Xeon(R) CPU E5-2618L v3 should support CAT.
> 
> I'm not sure which part is incorrect: the hardware or the software?
> (Hope Chao could give some insight about this.)
> 

Hmmm, from cpuid info it looks like this model does not support CAT. I'm
not sure which microarchitecture it is. But if it is broadwell, hardware
should support that, what you need is some fireware update, just as Andrew
has said. But otherwise it is haswell, then the hardware probably doesn't
support that. In that case the above link probably is also wrong. I can check
that internally.

Chao