[RFC tg_shares_up improvements - v1 07/12] sched: add sysctl_sched_shares_window

[pjt]

Introduce a new sysctl for the shares window and disambiguate it from
sched_time_avg.

A 10ms window appears to be a good compromise between accuracy and performance.

Signed-off-by: Paul Turner <pjt@xxxxxxxxxx>

---
 include/linux/sched.h |    1 +
 kernel/sched_fair.c   |    8 +++++++-
 kernel/sysctl.c       |    7 +++++++
 3 files changed, 15 insertions(+), 1 deletion(-)

Index: kernel/sched_fair.c
===================================================================
--- kernel/sched_fair.c.orig
+++ kernel/sched_fair.c
@@ -89,6 +89,12 @@ unsigned int normalized_sysctl_sched_wak
 
 const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
 
+/*
+ * The usage window over which average use is computed for shares
+ * distribution.
+ */
+unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL;
+
 static const struct sched_class fair_sched_class;
 
 /**************************************************************
@@ -688,7 +694,7 @@ account_entity_dequeue(struct cfs_rq *cf
 #if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
 static void update_cfs_load(struct cfs_rq *cfs_rq)
 {
-	u64 period = sched_avg_period();
+	u64 period = sysctl_sched_shares_window;
 	u64 now, delta;
 	unsigned long load = cfs_rq->load.weight;
 
Index: include/linux/sched.h
===================================================================
--- include/linux/sched.h.orig
+++ include/linux/sched.h
@@ -1883,6 +1883,7 @@ extern unsigned int sysctl_sched_migrati
 extern unsigned int sysctl_sched_nr_migrate;
 extern unsigned int sysctl_sched_time_avg;
 extern unsigned int sysctl_timer_migration;
+extern unsigned int sysctl_sched_shares_window;
 
 int sched_proc_update_handler(struct ctl_table *table, int write,
 		void __user *buffer, size_t *length,
Index: kernel/sysctl.c
===================================================================
--- kernel/sysctl.c.orig
+++ kernel/sysctl.c
@@ -337,6 +337,13 @@ static struct ctl_table kern_table[] = {
 		.proc_handler	= proc_dointvec,
 	},
 	{
+		.procname	= "sched_shares_window",
+		.data		= &sysctl_sched_shares_window,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{
 		.procname	= "timer_migration",
 		.data		= &sysctl_timer_migration,
 		.maxlen		= sizeof(unsigned int),

-- 

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