Re: Question about the CAT and CMT in Xen

[Meng Xu <xumengpanda@gmail.com>]

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. :-(

> 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.

Ah, could you please let me know if the link[1] is wrong?  If it does
not support CAT, I'm screwed. :'-(

[1]  http://www.intel.com/content/www/us/en/communications/cache-monitoring-cache-allocation-technologies.html

>
> Chao



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Meng Xu
PhD Student in Computer and Information Science
University of Pennsylvania
http://www.cis.upenn.edu/~mengxu/