linux-kernel - Re: [PATCH 1/2] cpufreq, intel_pstate, Fix limits->max_policy

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Date:	Fri, 20 Nov 2015 10:43:54 -0500
From:	Prarit Bhargava <prarit@...hat.com>
To:	Viresh Kumar <viresh.kumar@...aro.org>
CC:	linux-kernel@...r.kernel.org,
	Srinivas Pandruvada <srinivas.pandruvada@...el.com>,
	Len Brown <len.brown@...el.com>,
	Alexandra Yates <alexandra.yates@...el.com>,
	Kristen Carlson Accardi <kristen@...ux.intel.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>, linux-pm@...r.kernel.org
Subject: Re: [PATCH 1/2] cpufreq, intel_pstate, Fix limits->max_policy_pct
 rounding error



On 11/20/2015 10:19 AM, Viresh Kumar wrote:
> On 20-11-15, 10:10, Prarit Bhargava wrote:
>>>>  	limits->max_policy_pct = clamp_t(int, limits->max_policy_pct, 0 , 100);
>>>
>>> And put this after the later one ?
>>>
>>>> +	limits->max_policy_pct = DIV_ROUND_UP(policy->max * 100,
>>>> +					      policy->cpuinfo.max_freq);
>>>>  
>>>>  	/* Normalize user input to [min_policy_pct, max_policy_pct] */
>>>>  	limits->min_perf_pct = max(limits->min_policy_pct,
>>>
>>> Sure you tested it  ? :)
>>
>> Oops -- and yeah, tested.  It works because I rewrite the value of
>> max_policy_pct :).  I'll repost shortly.
> 
> But we aren't doing below anymore, doesn't this change the
> calculations at all?
> 
>   	limits->max_policy_pct = clamp_t(int, limits->max_policy_pct, 0 , 100);

The clamp only confines the max_policy between 0 and 100.  AFAIK it doesn't make
any change tothe value of limits->max_policy_pct unless it was outside of that
range.

P.
> 
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