5 files changed, 61 insertions, 2 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4b1ebd3280c6..ee9f200d12d3 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1902,13 +1902,22 @@ extern unsigned int sysctl_sched_wakeup_granularity;
 extern unsigned int sysctl_sched_shares_ratelimit;
 extern unsigned int sysctl_sched_shares_thresh;
 extern unsigned int sysctl_sched_child_runs_first;
+
+enum sched_tunable_scaling {
+        SCHED_TUNABLESCALING_NONE,
+        SCHED_TUNABLESCALING_LOG,
+        SCHED_TUNABLESCALING_LINEAR,
+        SCHED_TUNABLESCALING_END,
+};
+extern enum sched_tunable_scaling sysctl_sched_tunable_scaling;
+
 #ifdef CONFIG_SCHED_DEBUG
 extern unsigned int sysctl_sched_migration_cost;
 extern unsigned int sysctl_sched_nr_migrate;
 extern unsigned int sysctl_sched_time_avg;
 extern unsigned int sysctl_timer_migration;
 
-int sched_nr_latency_handler(struct ctl_table *table, int write,
+int sched_proc_update_handler(struct ctl_table *table, int write,
                 void __user *buffer, size_t *length,
                 loff_t *ppos);
 #endif
diff --git a/kernel/sched.c b/kernel/sched.c
index b54ecf84b6be..116efed962c6 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -7033,7 +7033,20 @@ cpumask_var_t nohz_cpu_mask;
 static void update_sysctl(void)
 {
         unsigned int cpus = min(num_online_cpus(), 8U);
-        unsigned int factor = 1 + ilog2(cpus);
+        unsigned int factor;
+
+        switch (sysctl_sched_tunable_scaling) {
+        case SCHED_TUNABLESCALING_NONE:
+                factor = 1;
+                break;
+        case SCHED_TUNABLESCALING_LINEAR:
+                factor = cpus;
+                break;
+        case SCHED_TUNABLESCALING_LOG:
+        default:
+                factor = 1 + ilog2(cpus);
+                break;
+        }
 
 #define SET_SYSCTL(name) \
         (sysctl_##name = (factor) * normalized_sysctl_##name)
diff --git a/kernel/sched_debug.c b/kernel/sched_debug.c
index 5fda66615fee..0fc5287fe80f 100644
--- a/kernel/sched_debug.c
+++ b/kernel/sched_debug.c
@@ -309,6 +309,12 @@ static void print_cpu(struct seq_file *m, int cpu)
         print_rq(m, rq, cpu);
 }
 
+static const char *sched_tunable_scaling_names[] = {
+        "none",
+        "logaritmic",
+        "linear"
+};
+
 static int sched_debug_show(struct seq_file *m, void *v)
 {
         u64 now = ktime_to_ns(ktime_get());
@@ -334,6 +340,10 @@ static int sched_debug_show(struct seq_file *m, void *v)
 #undef PN
 #undef P
 
+        SEQ_printf(m, "  .%-40s: %d (%s)\n", "sysctl_sched_tunable_scaling",
+                sysctl_sched_tunable_scaling,
+                sched_tunable_scaling_names[sysctl_sched_tunable_scaling]);
+
         for_each_online_cpu(cpu)
                 print_cpu(m, cpu);
 
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 71b3458245e5..455106d318a8 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -21,6 +21,7 @@
  */
 
 #include <linux/latencytop.h>
+#include <linux/sched.h>
 
 /*
  * Targeted preemption latency for CPU-bound tasks:
@@ -38,6 +39,18 @@ unsigned int sysctl_sched_latency = 5000000ULL;
 unsigned int normalized_sysctl_sched_latency = 5000000ULL;
 
 /*
+ * The initial- and re-scaling of tunables is configurable
+ * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus))
+ *
+ * Options are:
+ * SCHED_TUNABLESCALING_NONE - unscaled, always *1
+ * SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus)
+ * SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus
+ */
+enum sched_tunable_scaling sysctl_sched_tunable_scaling
+        = SCHED_TUNABLESCALING_LOG;
+
+/*
  * Minimal preemption granularity for CPU-bound tasks:
  * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds)
  */
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index e5cc53514caa..d10406e5fdfe 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -251,6 +251,8 @@ static int min_sched_granularity_ns = 100000;		/* 100 usecs */
 static int max_sched_granularity_ns = NSEC_PER_SEC;     /* 1 second */
 static int min_wakeup_granularity_ns;                   /* 0 usecs */
 static int max_wakeup_granularity_ns = NSEC_PER_SEC;    /* 1 second */
+static int min_sched_tunable_scaling = SCHED_TUNABLESCALING_NONE;
+static int max_sched_tunable_scaling = SCHED_TUNABLESCALING_END-1;
 #endif
 
 static struct ctl_table kern_table[] = {
@@ -306,6 +308,18 @@ static struct ctl_table kern_table[] = {
         },
         {
                 .ctl_name       = CTL_UNNUMBERED,
+                .procname       = "sched_tunable_scaling",
+                .data           = &sysctl_sched_tunable_scaling,
+                .maxlen         = sizeof(enum sched_tunable_scaling),
+                .mode           = 0644,
+                .proc_handler   = &proc_dointvec_minmax,
+                .strategy       = &sysctl_intvec,
+                .extra1         = &min_sched_tunable_scaling,
+                .extra2         = &max_sched_tunable_scaling,
+        },
+
+        {
+                .ctl_name       = CTL_UNNUMBERED,
                 .procname       = "sched_shares_thresh",
                 .data           = &sysctl_sched_shares_thresh,
                 .maxlen         = sizeof(unsigned int),