Re: bltk-game regressions on snb laptop

[Alex Shi <alex.shi@intel.com>]

On 04/18/2013 01:37 PM, Viresh Kumar wrote:
>>> >> About your system: Can you give output of cpufreq-info for v3.8 and
>>> >> v3.9-latestrc?
>>> >> Your cpus share a clock line or not?
>> >
>> > Yes our cpu shares a clock line. So the cpufreq-info is same. SNB CPU
>> > p-state is per cpu package, and hardware will coordinate the software
>> > asking, then decide which cpufreq should be.
> Can you paste cpufreq-info output, that will give us a better picture of your
> system.

will give you turbostat info later.
> 
>> > That's sth I am also confused. Yes, that cpu share a clock line. But
>> > Arjan and Len both said affected_cpus should only include the cpu self,
>> > because cpu will do hardware coordination for them.
> Why? we need a reason for that.... Do they mean Linux shouldn't be aware
> of any requirement of freq sync? But why?

Nope.
acpi_processor_preregister_performance() will read ACPI table and get the 
p-state coordinate type. I think that is the agreement between kernel and hardware.

Maybe the ondemand governor doesn't fit well with the laptop's p-state internal logical.
So, there is intel p-state driver for SNB, and it use different internal governor.

acpi_processor_preregister_performance():
715                 if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ALL)
716                         pr->performance->shared_type = CPUFREQ_SHARED_TYPE_ALL;
717                 else if (pdomain->coord_type == DOMAIN_COORD_TYPE_HW_ALL)
718                         pr->performance->shared_type = CPUFREQ_SHARED_TYPE_HW;
719                 else if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ANY)
720                         pr->performance->shared_type = CPUFREQ_SHARED_TYPE_ANY;
721 



-- 
Thanks Alex