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intel_pstate: Avoid pointless FRAC_BITS shifts under div_fp()

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There are multiple places in intel_pstate where int_tofp() is applied
to both arguments of div_fp(), but this is pointless, because int_tofp()
simply shifts its argument to the left by FRAC_BITS which mathematically
is equivalent to multuplication by 2^FRAC_BITS, so if this is done
to both arguments of a division, the extra factors will cancel each
other during that operation anyway.

Drop the pointless int_tofp() applied to div_fp() arguments throughout
the driver.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Rafael J. Wysocki 2016-04-09 01:25:58 +02:00
parent 2249c00a0b
commit 22590efb98
1 changed files with 13 additions and 18 deletions
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31
drivers/cpufreq/intel_pstate.c
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@ -341,17 +341,17 @@ static inline void pid_reset(struct _pid *pid, int setpoint, int busy,
static inline void pid_p_gain_set(struct _pid *pid, int percent)
{
pid->p_gain = div_fp(int_tofp(percent), int_tofp(100));
pid->p_gain = div_fp(percent, 100);
}
static inline void pid_i_gain_set(struct _pid *pid, int percent)
{
pid->i_gain = div_fp(int_tofp(percent), int_tofp(100));
pid->i_gain = div_fp(percent, 100);
}
static inline void pid_d_gain_set(struct _pid *pid, int percent)
{
pid->d_gain = div_fp(int_tofp(percent), int_tofp(100));
pid->d_gain = div_fp(percent, 100);
}
static signed int pid_calc(struct _pid *pid, int32_t busy)
@ -529,7 +529,7 @@ static ssize_t show_turbo_pct(struct kobject *kobj,
total = cpu->pstate.turbo_pstate - cpu->pstate.min_pstate + 1;
no_turbo = cpu->pstate.max_pstate - cpu->pstate.min_pstate + 1;
turbo_fp = div_fp(int_tofp(no_turbo), int_tofp(total));
turbo_fp = div_fp(no_turbo, total);
turbo_pct = 100 - fp_toint(mul_fp(turbo_fp, int_tofp(100)));
return sprintf(buf, "%u\n", turbo_pct);
}
@ -600,8 +600,7 @@ static ssize_t store_max_perf_pct(struct kobject *a, struct attribute *b,
limits->max_perf_pct);
limits->max_perf_pct = max(limits->min_perf_pct,
limits->max_perf_pct);
limits->max_perf = div_fp(int_tofp(limits->max_perf_pct),
int_tofp(100));
limits->max_perf = div_fp(limits->max_perf_pct, 100);
if (hwp_active)
intel_pstate_hwp_set_online_cpus();
@ -625,8 +624,7 @@ static ssize_t store_min_perf_pct(struct kobject *a, struct attribute *b,
limits->min_perf_pct);
limits->min_perf_pct = min(limits->max_perf_pct,
limits->min_perf_pct);
limits->min_perf = div_fp(int_tofp(limits->min_perf_pct),
int_tofp(100));
limits->min_perf = div_fp(limits->min_perf_pct, 100);
if (hwp_active)
intel_pstate_hwp_set_online_cpus();
@ -1011,8 +1009,8 @@ static inline void intel_pstate_calc_busy(struct cpudata *cpu)
struct sample *sample = &cpu->sample;
int64_t core_pct;
core_pct = int_tofp(sample->aperf) * int_tofp(100);
core_pct = div64_u64(core_pct, int_tofp(sample->mperf));
core_pct = sample->aperf * int_tofp(100);
core_pct = div64_u64(core_pct, sample->mperf);
sample->core_pct_busy = (int32_t)core_pct;
}
@ -1115,8 +1113,8 @@ static inline int32_t get_target_pstate_use_performance(struct cpudata *cpu)
* specified pstate.
*/
core_busy = cpu->sample.core_pct_busy;
max_pstate = int_tofp(cpu->pstate.max_pstate_physical);
current_pstate = int_tofp(cpu->pstate.current_pstate);
max_pstate = cpu->pstate.max_pstate_physical;
current_pstate = cpu->pstate.current_pstate;
core_busy = mul_fp(core_busy, div_fp(max_pstate, current_pstate));
/*
@ -1127,8 +1125,7 @@ static inline int32_t get_target_pstate_use_performance(struct cpudata *cpu)
*/
duration_ns = cpu->sample.time - cpu->last_sample_time;
if ((s64)duration_ns > pid_params.sample_rate_ns * 3) {
sample_ratio = div_fp(int_tofp(pid_params.sample_rate_ns),
int_tofp(duration_ns));
sample_ratio = div_fp(pid_params.sample_rate_ns, duration_ns);
core_busy = mul_fp(core_busy, sample_ratio);
}
@ -1328,10 +1325,8 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy)
/* Make sure min_perf_pct <= max_perf_pct */
limits->min_perf_pct = min(limits->max_perf_pct, limits->min_perf_pct);
limits->min_perf = div_fp(int_tofp(limits->min_perf_pct),
int_tofp(100));
limits->max_perf = div_fp(int_tofp(limits->max_perf_pct),
int_tofp(100));
limits->min_perf = div_fp(limits->min_perf_pct, 100);
limits->max_perf = div_fp(limits->max_perf_pct, 100);
out:
intel_pstate_set_update_util_hook(policy->cpu);