Re: Question about the CAT and CMT in Xen

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 01/09/15 13:55, Meng Xu wrote:
> 2015-09-01 1:47 GMT-04:00 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.
> According to http://www.cpu-world.com/CPUs/Xeon/Intel-Xeon%20E5-2618L%20v3.html,
> 2618L v3 is Haswell. :-(

Wikipedia agrees.

Haswell only has plain L3 cache usage information.

It is Broadwell which adds memory bandwidth monitoring, and Cache
Allocation.

~Andrew