Re: [PATCH v2] Documentation: cpufreq: intel_pstate: enhance documentation

[Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>]

On 12/28/2015 04:17 PM, Chen, Yu C wrote:
> Hi,
>
>> -----Original Message-----
>> From: linux-pm-owner@vger.kernel.org [mailto:linux-pm-
>> owner@vger.kernel.org] On Behalf Of Srinivas Pandruvada
>> Sent: Tuesday, December 29, 2015 2:15 AM
>> To: rafael@kernel.org; dsmythies@telus.net
>> Cc: Brown, Len; linux-pm@vger.kernel.org; Srinivas Pandruvada
>> Subject: [PATCH v2] Documentation: cpufreq: intel_pstate: enhance
>> documentation
>>
>> This is an attempt to make documentation more user friendly.
>>
>> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
>> ---
>> Changes in v2:
>> 	Suggested by Doug Smythies
>> 		- Grammar correction
>> 		- Use default PID and impact of setpoint on ramp up times
>>
>>
>>   Documentation/cpu-freq/intel-pstate.txt | 193
>> +++++++++++++++++++++++++-------
>>   1 file changed, 151 insertions(+), 42 deletions(-)
>>
>> diff --git a/Documentation/cpu-freq/intel-pstate.txt b/Documentation/cpu-
>> freq/intel-pstate.txt
>> index be8d400..5398a66 100644
>> --- a/Documentation/cpu-freq/intel-pstate.txt
>> +++ b/Documentation/cpu-freq/intel-pstate.txt
>> @@ -1,61 +1,131 @@
>> -Intel P-state driver
>> +Intel P-State driver
>>   --------------------
>>
>> +For the same load at setpoint = 60, this will result in the next
>> +P-State = 0x08 - ((60 - 100) * 0.2) = 16 So by changing the setpoint
>> +from 97 to 60, there is an increase of the next P-State from 9 to 16.
>> +So this will make processor execute at higher P-State for the same CPU
>> +load. If the load continues to be more than the setpoint during next
>> +sample intervals, then P-State will go up again till the maximum
>> +P-State is reached. But the ramp up time to reach the maximum P-State
>> +will be much faster when the setpoint is 60 compared to 97.
>> --
> Just inspired by another thread in the maillist, how about adding a description
> on suggesting  enable the ftrace  when user is trying to do some debug/tuning?
>

Good idea. Will add to next version.

Thanks,
Srinivas


> thanks,
> yu
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