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-rw-r--r--include/linux/sched.h11
-rw-r--r--kernel/sched.c15
-rw-r--r--kernel/sched_debug.c10
-rw-r--r--kernel/sched_fair.c13
-rw-r--r--kernel/sysctl.c14
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),