Re: [PATCH] intel_pstate: prevent max_perf_pct < min_perf_pct

[Seiichi Ikarashi <s.ikarashi@jp.fujitsu.com>]

Hi, Yu

On 2015-09-08 16:27, Chen, Yu C wrote:
> Hi, Seiichi
> 
>>> I guess a similar patch has been sent at:
>>> https://patchwork.kernel.org/patch/6995461/
>>
>> Yes, your patch looks better than mine from the point of view of covering
>> intel_pstate_set_policy().
>>
>> Still I have a question.
>> Does your patch allow the following condition?
>>
>>   limits.max_policy_pct > limits.min_perf_pct > limits.max_perf_pct >
>> limits.min_policy_pct
>>
> 
> Thanks!  Seems my previous patch does not guarantee
>  max_perf_pct >= min_perf_pct,  I think following logic would be better:
> Step0:  normalize the user input to [min_policy, max_policy]
> Step1: make sure max_perf_pct>= min_perf_pct
> 
> BTW,why I add step0 here is because we should not rely on user input, and
> different policy might have different (min,max), for example,
> max_policy_pct=40,min_policy_pct=30, and user input of 
> echo 50 > min_sysfs_pct would make the final min_perf_pct to
> 50, it's not in legal policy scope, so...

Those two steps will make sense.
I will review your upcoming v2 patch.

Regards,
Seiichi