diff options
| -rw-r--r-- | drivers/cpufreq/cpufreq_ondemand.c | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c index a87dc5d..e151adc 100644 --- a/drivers/cpufreq/cpufreq_ondemand.c +++ b/drivers/cpufreq/cpufreq_ondemand.c @@ -85,6 +85,7 @@ struct cpu_dbs_info_s { cputime64_t prev_cpu_idle; cputime64_t prev_cpu_iowait; cputime64_t prev_cpu_wall; + unsigned int prev_cpu_wall_delta; cputime64_t prev_cpu_nice; struct cpufreq_policy *cur_policy; struct delayed_work work; @@ -608,6 +609,10 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info) unsigned int idle_time, wall_time, iowait_time; unsigned int load, load_freq; int freq_avg; + bool deep_sleep_detected = false; + /* the evil magic numbers, only 2 at least */ + const unsigned int deep_sleep_backoff = 10; + const unsigned int deep_sleep_factor = 5; j_dbs_info = &per_cpu(od_cpu_dbs_info, j); @@ -618,6 +623,32 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info) j_dbs_info->prev_cpu_wall); j_dbs_info->prev_cpu_wall = cur_wall_time; + /* + * Ignore wall delta jitters in both directions. An + * exceptionally long wall_time will likely result + * idle but it was waken up to do work so the next + * slice is less likely to want to run at low + * frequency. Let's evaluate the next slice instead of + * the idle long one that passed already and it's too + * late to reduce in frequency. As opposed an + * exceptionally short slice that just run at low + * frequency is unlikely to be idle, but we may go + * back to idle pretty soon and that not idle slice + * already passed. If short slices will keep coming + * after a series of long slices the exponential + * backoff will converge faster and we'll react faster + * to high load. As opposed we'll decay slower + * towards low load and long idle times. + */ + if (j_dbs_info->prev_cpu_wall_delta > + wall_time * deep_sleep_factor || + j_dbs_info->prev_cpu_wall_delta * deep_sleep_factor < + wall_time) + deep_sleep_detected = true; + j_dbs_info->prev_cpu_wall_delta = + (j_dbs_info->prev_cpu_wall_delta * deep_sleep_backoff + + wall_time) / (deep_sleep_backoff+1); + idle_time = (unsigned int) cputime64_sub(cur_idle_time, j_dbs_info->prev_cpu_idle); j_dbs_info->prev_cpu_idle = cur_idle_time; @@ -643,6 +674,9 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info) idle_time += jiffies_to_usecs(cur_nice_jiffies); } + if (deep_sleep_detected) + continue; + /* * For the purpose of ondemand, waiting for disk IO is an * indication that you're performance critical, and not that |