Messages in this thread | | | Date | Thu, 19 Nov 2015 14:07:37 -0500 | From | Prarit Bhargava <> | Subject | Re: [PATCH] cpufreq, intel_pstate.c, Fix rounding errors |
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On 11/18/2015 11:46 PM, Viresh Kumar wrote: > On 18-11-15, 10:55, Prarit Bhargava wrote: >> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c >> index 2e31d09..686f024 100644 >> --- a/drivers/cpufreq/intel_pstate.c >> +++ b/drivers/cpufreq/intel_pstate.c >> @@ -1233,6 +1233,8 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy) >> struct cpudata *cpu; >> int i; >> #endif >> + int max_policy_calc; >> + >> pr_debug("intel_pstate: %s max %u policy->max %u\n", __func__, >> policy->cpuinfo.max_freq, policy->max); >> if (!policy->cpuinfo.max_freq) >> @@ -1249,7 +1251,10 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy) >> limits = &powersave_limits; >> limits->min_policy_pct = (policy->min * 100) / policy->cpuinfo.max_freq; >> limits->min_policy_pct = clamp_t(int, limits->min_policy_pct, 0 , 100); >> - limits->max_policy_pct = (policy->max * 100) / policy->cpuinfo.max_freq; >> + >> + max_policy_calc = (policy->max * 1000) / policy->cpuinfo.max_freq; >> + limits->max_policy_pct = DIV_ROUND_UP(max_policy_calc, 10); >> + > > Nice catch, but why can't we do this instead: > > limits->max_policy_pct = DIV_ROUND_UP(policy->max * 100, policy->cpuinfo.max_freq); >
Ah, I got so deep into the code I didn't even think of simplifying the calculation. Thanks -- I'll do that instead.
>> limits->max_policy_pct = clamp_t(int, limits->max_policy_pct, 0 , 100); >> >> /* Normalize user input to [min_policy_pct, max_policy_pct] */ >> @@ -1269,6 +1274,7 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy) >> int_tofp(100)); >> limits->max_perf = div_fp(int_tofp(limits->max_perf_pct), >> int_tofp(100)); >> + limits->max_perf = round_up(limits->max_perf, 8); > > Perhaps you should fix this in a separate patch. >
Okay, I submit these as a 2 part patchset.
P.
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