sched: eliminate sched_upmigrate_min_nice knob

Kill unused scheduler knob sched_upmigrate_min_nice.

Change-Id: I53ddfde39c78e78306bd746c1c4da9a94ec67cd8
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>

Documentation/scheduler/sched-zone.txt

@@ -550,7 +550,7 @@ both tasks and CPUs to aid in the placement of tasks.
   particular CPU, that CPU will be considered too small for the task. The task
   will thus be seen as a "big" task on the cpu and will reflect in nr_big_tasks
   statistics maintained for that cpu. Note that certain tasks (whose nice
-  value exceeds sched_upmigrate_min_nice value or those that belong to a cgroup
+  value exceeds SCHED_UPMIGRATE_MIN_NICE value or those that belong to a cgroup
   whose upmigrate_discourage flag is set) will never be classified as big tasks
   despite their high demand.
 
@@ -666,7 +666,7 @@ offered by cluster. Criteria for a task to be considered as fitting in a cluster
 is:
 
  i) A low-priority task, whose nice value is greater than
-     sysctl_sched_upmigrate_min_nice or whose cgroup has its
+     SCHED_UPMIGRATE_MIN_NICE or whose cgroup has its
      upmigrate_discourage flag set, is considered to be fitting in all clusters,
      irrespective of their capacity and task's cpu demand.
 
@@ -775,7 +775,7 @@ available (idle) to service it
 b) A task is starving on a CPU with high irq load.
 
 c) A task with upmigration discouraged is running on a performance cluster.
-See notes on 'cpu.upmigrate_discourage' and sched_upmigrate_min_nice tunables.
+See notes on 'cpu.upmigrate_discourage'.
 
 In case the test for migration turns out positive (which is expected to be rare
 event), a candidate cpu is identified for task migration. To avoid multiple task
@@ -1037,19 +1037,7 @@ historical load value to assign to it. This tunable specifies the
 initial load value for newly created tasks. Also see Sec 2.8 on per-task
 'initial task load' attribute.
 
-*** 7.5 sched_upmigrate_min_nice
+*** 7.5 sched_ravg_hist_size
-
-Appears at: /proc/sys/kernel/sched_upmigrate_min_nice
-
-Default value: 15
-
-A task whose nice value is greater than this tunable value will never
-be considered as a "big" task (it will not be allowed to run on a
-high-performance CPU).
-
-See also notes on 'cpu.upmigrate_discourage' tunable.
-
-*** 7.6 sched_ravg_hist_size
 
 Appears at: /proc/sys/kernel/sched_ravg_hist_size
 
@@ -1058,7 +1046,7 @@ Default value: 5
 This tunable controls the number of samples used from task's sum_history[]
 array for determination of its demand.
 
-*** 7.7 sched_window_stats_policy
+*** 7.6 sched_window_stats_policy
 
 Appears at: /proc/sys/kernel/sched_window_stats_policy
 
@@ -1077,7 +1065,7 @@ Possible values for this tunable are:
    samples), where M = sysctl_sched_ravg_hist_size
 3. Use average of first M samples, where M = sysctl_sched_ravg_hist_size
 
-*** 7.8 sched_ravg_window
+*** 7.7 sched_ravg_window
 
 Appears at: kernel command line argument
 
@@ -1088,7 +1076,7 @@ tracking. By default each window is 10ms long. This quantity must
 currently be set at boot time on the kernel command line (or the
 default value of 10ms can be used).
 
-*** 7.9 RAVG_HIST_SIZE
+*** 7.8 RAVG_HIST_SIZE
 
 Appears at: compile time only (see RAVG_HIST_SIZE in include/linux/sched.h)
 
@@ -1099,7 +1087,7 @@ tracking mechanism maintains per task. If default values are used for
 both this and sched_ravg_window then a total of 50ms of task history
 would be maintained in 5 10ms windows.
 
-*** 7.10 sched_migration_fixup
+*** 7.9 sched_migration_fixup
 
 Appears at: /proc/sys/kernel/sched_migration_fixup
 
@@ -1108,7 +1096,7 @@ Default value: 1
 This controls whether a cpu's busy time counters are adjusted during task
 migration.
 
-*** 7.11 sched_freq_inc_notify
+*** 7.10 sched_freq_inc_notify
 
 Appears at: /proc/sys/kernel/sched_freq_inc_notify
 
@@ -1120,7 +1108,7 @@ exceeds sched_freq_inc_notify, where freq_required is the frequency calculated
 by scheduler to meet current task demand. Note that sched_freq_inc_notify is
 specified in kHz units.
 
-*** 7.12 sched_freq_dec_notify
+*** 7.11 sched_freq_dec_notify
 
 Appears at: /proc/sys/kernel/sched_freq_dec_notify
 
@@ -1133,7 +1121,7 @@ exceeds sched_freq_dec_notify, where freq_required is the frequency calculated
 by scheduler to meet current task demand. Note that sched_freq_dec_notify is
 specified in kHz units.
 
-*** 7.13 sched_heavy_task
+*** 7.12 sched_heavy_task
 
 Appears at: /proc/sys/kernel/sched_heavy_task
 
@@ -1145,7 +1133,7 @@ comparison. Scheduler will request a raise in cpu frequency when heavy tasks
 wakeup after at least one window of sleep, where window size is defined by
 sched_ravg_window. Value 0 will disable this feature.
 
-*** 7.14 sched_cpu_high_irqload
+*** 7.13 sched_cpu_high_irqload
 
 Appears at: /proc/sys/kernel/sched_cpu_high_irqload
 
@@ -1163,7 +1151,7 @@ longer eligible for placement. This will affect the task placement logic
 described above, causing the scheduler to try and steer tasks away from
 the CPU.
 
-*** 7.15 cpu.upmigrate_discourage
+*** 7.14 cpu.upmigrate_discourage
 
 Default value : 0
 
@@ -1176,10 +1164,9 @@ Setting this flag to 1 discourages upmigration for all tasks of a cgroup. High
 demand tasks of such a cgroup will never be classified as big tasks and hence
 not upmigrated. Any task of the cgroup is allowed to upmigrate only under
 overcommitted scenario. See notes on sched_spill_nr_run and sched_spill_load for
-how overcommitment threshold is defined and also notes on
+how overcommitment threshold is defined.
-'sched_upmigrate_min_nice' tunable.
 
-*** 7.16 sched_static_cpu_pwr_cost
+*** 7.15 sched_static_cpu_pwr_cost
 
 Default value: 0
 
@@ -1194,7 +1181,7 @@ within a cluster and possibly have differing value between clusters as
 needed.
 
 
-*** 7.17 sched_static_cluster_pwr_cost
+*** 7.16 sched_static_cluster_pwr_cost
 
 Default value: 0
 
@@ -1205,7 +1192,7 @@ power mode. It ignores the actual D-state that a cluster may be in and assumes
 the worst case power cost of the highest D-state. It is means of biasing task
 placement away from idle clusters when necessary.
 
-*** 7.18 sched_early_detection_duration
+*** 7.17 sched_early_detection_duration
 
 Default value: 9500000
 
@@ -1216,7 +1203,7 @@ tick for it to be eligible for the scheduler's early detection feature
 under scheduler boost. For more information on the feature itself please
 refer to section 5.2.1.
 
-*** 7.19 sched_restrict_cluster_spill
+*** 7.18 sched_restrict_cluster_spill
 
 Default value: 0
 
@@ -1235,7 +1222,7 @@ CPU across all clusters. When this tunable is enabled, the RT tasks are
 restricted to the lowest possible power cluster.
 
 
-*** 7.20 sched_downmigrate
+*** 7.19 sched_downmigrate
 
 Appears at: /proc/sys/kernel/sched_downmigrate
 
@@ -1248,7 +1235,7 @@ its demand *in reference to the power-efficient cpu* drops less than 60%
 (sched_downmigrate).
 
 
-*** 7.21 sched_small_wakee_task_load
+*** 7.20 sched_small_wakee_task_load
 
 Appears at: /proc/sys/kernel/sched_small_wakee_task_load
 
@@ -1260,7 +1247,7 @@ categorized as small wakee tasks.  Scheduler places small wakee tasks on the
 waker's cluster.
 
 
-*** 7.22 sched_big_waker_task_load
+*** 7.21 sched_big_waker_task_load
 
 Appears at: /proc/sys/kernel/sched_big_waker_task_load
 

include/linux/sched/sysctl.h

@@ -61,7 +61,6 @@ extern unsigned int sysctl_sched_spill_nr_run;
 extern unsigned int sysctl_sched_spill_load_pct;
 extern unsigned int sysctl_sched_upmigrate_pct;
 extern unsigned int sysctl_sched_downmigrate_pct;
-extern int sysctl_sched_upmigrate_min_nice;
 extern unsigned int sysctl_early_detection_duration;
 extern unsigned int sysctl_sched_boost;
 extern unsigned int sysctl_sched_small_wakee_task_load_pct;

kernel/sched/fair.c

@@ -2753,12 +2753,7 @@ unsigned int __read_mostly sysctl_sched_upmigrate_pct = 80;
 unsigned int __read_mostly sched_downmigrate;
 unsigned int __read_mostly sysctl_sched_downmigrate_pct = 60;
 
-/*
+#define SCHED_UPMIGRATE_MIN_NICE 15
- * Tasks whose nice value is > sysctl_sched_upmigrate_min_nice are never
- * considered as "big" tasks.
- */
-static int __read_mostly sched_upmigrate_min_nice = 15;
-int __read_mostly sysctl_sched_upmigrate_min_nice = 15;
 
 /*
  * The load scale factor of a CPU gets boosted when its max frequency
@@ -2837,8 +2832,6 @@ void set_hmp_defaults(void)
 		div64_u64((u64)sysctl_sched_init_task_load_pct *
 			  (u64)sched_ravg_window, 100);
 
-	sched_upmigrate_min_nice = sysctl_sched_upmigrate_min_nice;
-
 	sched_short_sleep_task_threshold = sysctl_sched_select_prev_cpu_us *
 					   NSEC_PER_USEC;
 
@@ -2887,7 +2880,7 @@ static inline int __is_big_task(struct task_struct *p, u64 scaled_load)
 {
 	int nice = task_nice(p);
 
-	if (nice > sched_upmigrate_min_nice || upmigrate_discouraged(p))
+	if (nice > SCHED_UPMIGRATE_MIN_NICE || upmigrate_discouraged(p))
 		return 0;
 
 	return scaled_load > sched_upmigrate;
@@ -3002,7 +2995,7 @@ static int task_load_will_fit(struct task_struct *p, u64 task_load, int cpu,
 		return 1;
 
 	if (boost_type != SCHED_BOOST_ON_BIG) {
-		if (task_nice(p) > sched_upmigrate_min_nice ||
+		if (task_nice(p) > SCHED_UPMIGRATE_MIN_NICE ||
 		    upmigrate_discouraged(p))
 			return 1;
 
@@ -4134,16 +4127,9 @@ int sched_hmp_proc_update_handler(struct ctl_table *table, int write,
 	if (write && (old_val == *data))
 		goto done;
 
-	if (data == (unsigned int *)&sysctl_sched_upmigrate_min_nice) {
+	if (data != &sysctl_sched_select_prev_cpu_us) {
-		if ((*(int *)data) < -20 || (*(int *)data) > 19) {
-			*data = old_val;
-			ret = -EINVAL;
-			goto done;
-		}
-		update_min_nice = 1;
-	} else if (data != &sysctl_sched_select_prev_cpu_us) {
 		/*
-		 * all tunables other than min_nice and prev_cpu_us are
+		 * all tunables other than sched_select_prev_cpu_us are
 		 * in percentage.
 		 */
 		if (sysctl_sched_downmigrate_pct >
@@ -4226,7 +4212,7 @@ static inline int migration_needed(struct task_struct *p, int cpu)
 	nice = task_nice(p);
 	rcu_read_lock();
 	grp = task_related_thread_group(p);
-	if (!grp && (nice > sched_upmigrate_min_nice ||
+	if (!grp && (nice > SCHED_UPMIGRATE_MIN_NICE ||
 	       upmigrate_discouraged(p)) && cpu_capacity(cpu) > min_capacity) {
 		rcu_read_unlock();
 		return DOWN_MIGRATION;

kernel/sysctl.c

@@ -382,13 +382,6 @@ static struct ctl_table kern_table[] = {
 		.mode		= 0644,
 		.proc_handler	= sched_hmp_proc_update_handler,
 	},
-	{
-		.procname	= "sched_upmigrate_min_nice",
-		.data		= &sysctl_sched_upmigrate_min_nice,
-		.maxlen		= sizeof(unsigned int),
-		.mode		= 0644,
-		.proc_handler	= sched_hmp_proc_update_handler,
-	},
 	{
 		.procname	= "sched_init_task_load",
 		.data		= &sysctl_sched_init_task_load_pct,