From: Stratos Karafotis stratosk@semaphore.gr
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: Stratos Karafotis stratosk@semaphore.gr Acked-by: Viresh Kumar <viresh.kumar@linaro.,org> Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com --- drivers/cpufreq/cpufreq_conservative.c | 2 +- drivers/cpufreq/cpufreq_governor.c | 48 +++++++++++++--------------------- drivers/cpufreq/cpufreq_governor.h | 3 +-- drivers/cpufreq/cpufreq_ondemand.c | 11 +++++++- 4 files changed, 30 insertions(+), 34 deletions(-)
diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c index 98b4946..2465e63 100644 --- a/drivers/cpufreq/cpufreq_conservative.c +++ b/drivers/cpufreq/cpufreq_conservative.c @@ -238,7 +238,7 @@ 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]; diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c index 38f959b..13ca17a 100644 --- a/drivers/cpufreq/cpufreq_governor.c +++ b/drivers/cpufreq/cpufreq_governor.c @@ -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;
@@ -236,6 +222,7 @@ 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()) @@ -338,6 +325,7 @@ 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) { @@ -354,7 +342,7 @@ 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]; diff --git a/drivers/cpufreq/cpufreq_governor.h b/drivers/cpufreq/cpufreq_governor.h index 8998d3d..eae3163 100644 --- a/drivers/cpufreq/cpufreq_governor.h +++ b/drivers/cpufreq/cpufreq_governor.h @@ -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; @@ -257,7 +256,7 @@ 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); diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c index 15e80ee..8500147 100644 --- a/drivers/cpufreq/cpufreq_ondemand.c +++ b/drivers/cpufreq/cpufreq_ondemand.c @@ -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];