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cpufreq: schedutil: Add iowait boosting

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Modify the schedutil cpufreq governor to boost the CPU
frequency if the SCHED_CPUFREQ_IOWAIT flag is passed to
it via cpufreq_update_util().

If that happens, the frequency is set to the maximum during
the first update after receiving the SCHED_CPUFREQ_IOWAIT flag
and then the boost is reduced by half during each following update.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Looks-good-to: Steve Muckle <smuckle@linaro.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
This commit is contained in:
Rafael J. Wysocki 2016-09-10 00:00:31 +02:00
parent 8c34ab1910
commit 21ca6d2c52
1 changed files with 49 additions and 4 deletions
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53
kernel/sched/cpufreq_schedutil.c
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@ -47,11 +47,13 @@ struct sugov_cpu {
struct sugov_policy *sg_policy;
unsigned int cached_raw_freq;
unsigned long iowait_boost;
unsigned long iowait_boost_max;
u64 last_update;
/* The fields below are only needed when sharing a policy. */
unsigned long util;
unsigned long max;
u64 last_update;
unsigned int flags;
};
@ -155,6 +157,36 @@ static void sugov_get_util(unsigned long *util, unsigned long *max)
*max = cfs_max;
}
static void sugov_set_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
unsigned int flags)
{
if (flags & SCHED_CPUFREQ_IOWAIT) {
sg_cpu->iowait_boost = sg_cpu->iowait_boost_max;
} else if (sg_cpu->iowait_boost) {
s64 delta_ns = time - sg_cpu->last_update;
/* Clear iowait_boost if the CPU apprears to have been idle. */
if (delta_ns > TICK_NSEC)
sg_cpu->iowait_boost = 0;
}
}
static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, unsigned long *util,
unsigned long *max)
{
unsigned long boost_util = sg_cpu->iowait_boost;
unsigned long boost_max = sg_cpu->iowait_boost_max;
if (!boost_util)
return;
if (*util * boost_max < *max * boost_util) {
*util = boost_util;
*max = boost_max;
}
sg_cpu->iowait_boost >>= 1;
}
static void sugov_update_single(struct update_util_data *hook, u64 time,
unsigned int flags)
{
@ -164,6 +196,9 @@ static void sugov_update_single(struct update_util_data *hook, u64 time,
unsigned long util, max;
unsigned int next_f;
sugov_set_iowait_boost(sg_cpu, time, flags);
sg_cpu->last_update = time;
if (!sugov_should_update_freq(sg_policy, time))
return;
@ -171,6 +206,7 @@ static void sugov_update_single(struct update_util_data *hook, u64 time,
next_f = policy->cpuinfo.max_freq;
} else {
sugov_get_util(&util, &max);
sugov_iowait_boost(sg_cpu, &util, &max);
next_f = get_next_freq(sg_cpu, util, max);
}
sugov_update_commit(sg_policy, time, next_f);
@ -189,6 +225,8 @@ static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu,
if (flags & SCHED_CPUFREQ_RT_DL)
return max_f;
sugov_iowait_boost(sg_cpu, &util, &max);
for_each_cpu(j, policy->cpus) {
struct sugov_cpu *j_sg_cpu;
unsigned long j_util, j_max;
@ -203,12 +241,13 @@ static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu,
* frequency update and the time elapsed between the last update
* of the CPU utilization and the last frequency update is long
* enough, don't take the CPU into account as it probably is
* idle now.
* idle now (and clear iowait_boost for it).
*/
delta_ns = last_freq_update_time - j_sg_cpu->last_update;
if (delta_ns > TICK_NSEC)
if (delta_ns > TICK_NSEC) {
j_sg_cpu->iowait_boost = 0;
continue;
}
if (j_sg_cpu->flags & SCHED_CPUFREQ_RT_DL)
return max_f;
@ -218,6 +257,8 @@ static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu,
util = j_util;
max = j_max;
}
sugov_iowait_boost(j_sg_cpu, &util, &max);
}
return get_next_freq(sg_cpu, util, max);
@ -238,6 +279,8 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time,
sg_cpu->util = util;
sg_cpu->max = max;
sg_cpu->flags = flags;
sugov_set_iowait_boost(sg_cpu, time, flags);
sg_cpu->last_update = time;
if (sugov_should_update_freq(sg_policy, time)) {
@ -470,6 +513,8 @@ static int sugov_start(struct cpufreq_policy *policy)
sg_cpu->flags = SCHED_CPUFREQ_RT;
sg_cpu->last_update = 0;
sg_cpu->cached_raw_freq = 0;
sg_cpu->iowait_boost = 0;
sg_cpu->iowait_boost_max = policy->cpuinfo.max_freq;
cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util,
sugov_update_shared);
} else {