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cpufreq: intel_pstate: Use IOWAIT flag in Atom algorithm

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Modify the P-state selection algorithm for Atom processors to use
the new SCHED_CPUFREQ_IOWAIT flag instead of the questionable
get_cpu_iowait_time_us() function.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Rafael J. Wysocki 2016-09-14 02:28:13 +02:00
parent 21ca6d2c52
commit 09c448d3c6
1 changed files with 31 additions and 27 deletions
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58
drivers/cpufreq/intel_pstate.c
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@ -181,6 +181,8 @@ struct _pid {
* @cpu: CPU number for this instance data
* @update_util: CPUFreq utility callback information
* @update_util_set: CPUFreq utility callback is set
* @iowait_boost: iowait-related boost fraction
* @last_update: Time of the last update.
* @pstate: Stores P state limits for this CPU
* @vid: Stores VID limits for this CPU
* @pid: Stores PID parameters for this CPU
@ -206,6 +208,7 @@ struct cpudata {
struct vid_data vid;
struct _pid pid;
u64 last_update;
u64 last_sample_time;
u64 prev_aperf;
u64 prev_mperf;
@ -216,6 +219,7 @@ struct cpudata {
struct acpi_processor_performance acpi_perf_data;
bool valid_pss_table;
#endif
unsigned int iowait_boost;
};
static struct cpudata **all_cpu_data;
@ -229,6 +233,7 @@ static struct cpudata **all_cpu_data;
* @p_gain_pct: PID proportional gain
* @i_gain_pct: PID integral gain
* @d_gain_pct: PID derivative gain
* @boost_iowait: Whether or not to use iowait boosting.
*
* Stores per CPU model static PID configuration data.
*/
@ -240,6 +245,7 @@ struct pstate_adjust_policy {
int p_gain_pct;
int d_gain_pct;
int i_gain_pct;
bool boost_iowait;
};
/**
@ -1037,6 +1043,7 @@ static struct cpu_defaults silvermont_params = {
.p_gain_pct = 14,
.d_gain_pct = 0,
.i_gain_pct = 4,
.boost_iowait = true,
},
.funcs = {
.get_max = atom_get_max_pstate,
@ -1058,6 +1065,7 @@ static struct cpu_defaults airmont_params = {
.p_gain_pct = 14,
.d_gain_pct = 0,
.i_gain_pct = 4,
.boost_iowait = true,
},
.funcs = {
.get_max = atom_get_max_pstate,
@ -1099,6 +1107,7 @@ static struct cpu_defaults bxt_params = {
.p_gain_pct = 14,
.d_gain_pct = 0,
.i_gain_pct = 4,
.boost_iowait = true,
},
.funcs = {
.get_max = core_get_max_pstate,
@ -1222,36 +1231,18 @@ static inline int32_t get_avg_pstate(struct cpudata *cpu)
static inline int32_t get_target_pstate_use_cpu_load(struct cpudata *cpu)
{
struct sample *sample = &cpu->sample;
u64 cummulative_iowait, delta_iowait_us;
u64 delta_iowait_mperf;
u64 mperf, now;
int32_t cpu_load;
int32_t busy_frac, boost;
cummulative_iowait = get_cpu_iowait_time_us(cpu->cpu, &now);
busy_frac = div_fp(sample->mperf, sample->tsc);
/*
* Convert iowait time into number of IO cycles spent at max_freq.
* IO is considered as busy only for the cpu_load algorithm. For
* performance this is not needed since we always try to reach the
* maximum P-State, so we are already boosting the IOs.
*/
delta_iowait_us = cummulative_iowait - cpu->prev_cummulative_iowait;
delta_iowait_mperf = div64_u64(delta_iowait_us * cpu->pstate.scaling *
cpu->pstate.max_pstate, MSEC_PER_SEC);
boost = cpu->iowait_boost;
cpu->iowait_boost >>= 1;
mperf = cpu->sample.mperf + delta_iowait_mperf;
cpu->prev_cummulative_iowait = cummulative_iowait;
if (busy_frac < boost)
busy_frac = boost;
/*
* The load can be estimated as the ratio of the mperf counter
* running at a constant frequency during active periods
* (C0) and the time stamp counter running at the same frequency
* also during C-states.
*/
cpu_load = div64_u64(int_tofp(100) * mperf, sample->tsc);
cpu->sample.busy_scaled = cpu_load;
return get_avg_pstate(cpu) - pid_calc(&cpu->pid, cpu_load);
sample->busy_scaled = busy_frac * 100;
return get_avg_pstate(cpu) - pid_calc(&cpu->pid, sample->busy_scaled);
}
static inline int32_t get_target_pstate_use_performance(struct cpudata *cpu)
@ -1332,8 +1323,21 @@ static void intel_pstate_update_util(struct update_util_data *data, u64 time,
unsigned int flags)
{
struct cpudata *cpu = container_of(data, struct cpudata, update_util);
u64 delta_ns = time - cpu->sample.time;
u64 delta_ns;
if (pid_params.boost_iowait) {
if (flags & SCHED_CPUFREQ_IOWAIT) {
cpu->iowait_boost = int_tofp(1);
} else if (cpu->iowait_boost) {
/* Clear iowait_boost if the CPU may have been idle. */
delta_ns = time - cpu->last_update;
if (delta_ns > TICK_NSEC)
cpu->iowait_boost = 0;
}
cpu->last_update = time;
}
delta_ns = time - cpu->sample.time;
if ((s64)delta_ns >= pid_params.sample_rate_ns) {
bool sample_taken = intel_pstate_sample(cpu, time);