Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 9366d840 authored by Stratos Karafotis's avatar Stratos Karafotis Committed by Rafael J. Wysocki
Browse files

cpufreq: governors: Calculate iowait time only when necessary 



Currently we always calculate the CPU iowait time and add it to idle time.
If we are in ondemand and we use io_is_busy, we re-calculate iowait time
and we subtract it from idle time.

With this patch iowait time is calculated only when necessary avoiding
the double call to get_cpu_iowait_time_us. We use a parameter in
function get_cpu_idle_time to distinguish when the iowait time will be
added to idle time or not, without the need of keeping the prev_io_wait.

Signed-off-by: default avatarStratos Karafotis <stratosk@semaphore.gr>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.,org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent fed573d5

drivers/cpufreq/cpufreq_conservative.c

+1 −1
Original line number Diff line number Diff line
@@ -240,7 +240,7 @@ static ssize_t store_ignore_nice(struct dbs_data *dbs_data, const char *buf, 
		struct cs_cpu_dbs_info_s *dbs_info;

		dbs_info = &per_cpu(cs_cpu_dbs_info, j);

		dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,

						&dbs_info->cdbs.prev_cpu_wall);

					&dbs_info->cdbs.prev_cpu_wall, 0);

		if (cs_tuners->ignore_nice)

			dbs_info->cdbs.prev_cpu_nice =

				kcpustat_cpu(j).cpustat[CPUTIME_NICE];

drivers/cpufreq/cpufreq_governor.c

+18 −30
Original line number Diff line number Diff line
@@ -67,13 +67,13 @@ static inline u64 get_cpu_idle_time_jiffy(unsigned int cpu, u64 *wall) 
	return cputime_to_usecs(idle_time);

}



u64 get_cpu_idle_time(unsigned int cpu, u64 *wall)

u64 get_cpu_idle_time(unsigned int cpu, u64 *wall, int io_busy)

{

	u64 idle_time = get_cpu_idle_time_us(cpu, NULL);

	u64 idle_time = get_cpu_idle_time_us(cpu, io_busy ? wall : NULL);



	if (idle_time == -1ULL)

		return get_cpu_idle_time_jiffy(cpu, wall);

	else

	else if (!io_busy)

		idle_time += get_cpu_iowait_time_us(cpu, wall);



	return idle_time;
@@ -100,13 +100,22 @@ void dbs_check_cpu(struct dbs_data *dbs_data, int cpu) 
	/* Get Absolute Load (in terms of freq for ondemand gov) */

	for_each_cpu(j, policy->cpus) {

		struct cpu_dbs_common_info *j_cdbs;

		u64 cur_wall_time, cur_idle_time, cur_iowait_time;

		unsigned int idle_time, wall_time, iowait_time;

		u64 cur_wall_time, cur_idle_time;

		unsigned int idle_time, wall_time;

		unsigned int load;

		int io_busy = 0;



		j_cdbs = dbs_data->cdata->get_cpu_cdbs(j);



		cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);

		/*

		 * For the purpose of ondemand, waiting for disk IO is

		 * an indication that you're performance critical, and

		 * not that the system is actually idle. So do not add

		 * the iowait time to the cpu idle time.

		 */

		if (dbs_data->cdata->governor == GOV_ONDEMAND)

			io_busy = od_tuners->io_is_busy;

		cur_idle_time = get_cpu_idle_time(j, &cur_wall_time, io_busy);



		wall_time = (unsigned int)

			(cur_wall_time - j_cdbs->prev_cpu_wall);
@@ -134,29 +143,6 @@ void dbs_check_cpu(struct dbs_data *dbs_data, int cpu) 
			idle_time += jiffies_to_usecs(cur_nice_jiffies);

		}



		if (dbs_data->cdata->governor == GOV_ONDEMAND) {

			struct od_cpu_dbs_info_s *od_j_dbs_info =

				dbs_data->cdata->get_cpu_dbs_info_s(cpu);



			cur_iowait_time = get_cpu_iowait_time_us(j,

					&cur_wall_time);

			if (cur_iowait_time == -1ULL)

				cur_iowait_time = 0;



			iowait_time = (unsigned int) (cur_iowait_time -

					od_j_dbs_info->prev_cpu_iowait);

			od_j_dbs_info->prev_cpu_iowait = cur_iowait_time;



			/*

			 * For the purpose of ondemand, waiting for disk IO is

			 * an indication that you're performance critical, and

			 * not that the system is actually idle. So subtract the

			 * iowait time from the cpu idle time.

			 */

			if (od_tuners->io_is_busy && idle_time >= iowait_time)

				idle_time -= iowait_time;

		}



		if (unlikely(!wall_time || wall_time < idle_time))

			continue;
@@ -254,6 +240,7 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy, 
	struct cs_dbs_tuners *cs_tuners = NULL;

	struct cpu_dbs_common_info *cpu_cdbs;

	unsigned int sampling_rate, latency, ignore_nice, j, cpu = policy->cpu;

	int io_busy = 0;

	int rc;



	if (have_governor_per_policy())
@@ -353,6 +340,7 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy, 
		sampling_rate = od_tuners->sampling_rate;

		ignore_nice = od_tuners->ignore_nice;

		od_ops = dbs_data->cdata->gov_ops;

		io_busy = od_tuners->io_is_busy;

	}



	switch (event) {
@@ -369,7 +357,7 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy, 
			j_cdbs->cpu = j;

			j_cdbs->cur_policy = policy;

			j_cdbs->prev_cpu_idle = get_cpu_idle_time(j,

					&j_cdbs->prev_cpu_wall);

					       &j_cdbs->prev_cpu_wall, io_busy);

			if (ignore_nice)

				j_cdbs->prev_cpu_nice =

					kcpustat_cpu(j).cpustat[CPUTIME_NICE];

drivers/cpufreq/cpufreq_governor.h

+1 −2
Original line number Diff line number Diff line
@@ -148,7 +148,6 @@ struct cpu_dbs_common_info { 


struct od_cpu_dbs_info_s {

	struct cpu_dbs_common_info cdbs;

	u64 prev_cpu_iowait;

	struct cpufreq_frequency_table *freq_table;

	unsigned int freq_lo;

	unsigned int freq_lo_jiffies;
@@ -256,7 +255,7 @@ static ssize_t show_sampling_rate_min_gov_pol \ 
	return sprintf(buf, "%u\n", dbs_data->min_sampling_rate);	\

}



u64 get_cpu_idle_time(unsigned int cpu, u64 *wall);

u64 get_cpu_idle_time(unsigned int cpu, u64 *wall, int io_busy);

void dbs_check_cpu(struct dbs_data *dbs_data, int cpu);

bool need_load_eval(struct cpu_dbs_common_info *cdbs,

		unsigned int sampling_rate);

drivers/cpufreq/cpufreq_ondemand.c

+10 −1
Original line number Diff line number Diff line
@@ -339,11 +339,20 @@ static ssize_t store_io_is_busy(struct dbs_data *dbs_data, const char *buf, 
	struct od_dbs_tuners *od_tuners = dbs_data->tuners;

	unsigned int input;

	int ret;

	unsigned int j;



	ret = sscanf(buf, "%u", &input);

	if (ret != 1)

		return -EINVAL;

	od_tuners->io_is_busy = !!input;



	/* we need to re-evaluate prev_cpu_idle */

	for_each_online_cpu(j) {

		struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,

									j);

		dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,

			&dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy);

	}

	return count;

}
@@ -414,7 +423,7 @@ static ssize_t store_ignore_nice(struct dbs_data *dbs_data, const char *buf, 
		struct od_cpu_dbs_info_s *dbs_info;

		dbs_info = &per_cpu(od_cpu_dbs_info, j);

		dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,

						&dbs_info->cdbs.prev_cpu_wall);

			&dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy);

		if (od_tuners->ignore_nice)

			dbs_info->cdbs.prev_cpu_nice =

				kcpustat_cpu(j).cpustat[CPUTIME_NICE];