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authorClark Williams <williams@redhat.com>2013-02-07 09:47:04 -0600
committerIngo Molnar <mingo@kernel.org>2013-02-07 20:51:07 +0100
commitce0dbbbb30aee6a835511d5be446462388ba9eee (patch)
treec3d4d6f64a0fe7eec9283f4413d111a8d37d7053
parentcf4aebc292fac7f34f8345664320e9d4a42ca76c (diff)
sched/rt: Add a tuning knob to allow changing SCHED_RR timeslice
Add a /proc/sys/kernel scheduler knob named sched_rr_timeslice_ms that allows global changing of the SCHED_RR timeslice value. User visable value is in milliseconds but is stored as jiffies. Setting to 0 (zero) resets to the default (currently 100ms). Signed-off-by: Clark Williams <williams@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20130207094704.13751796@riff.lan Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--include/linux/sched/sysctl.h15
-rw-r--r--kernel/sched/core.c19
-rw-r--r--kernel/sched/rt.c6
-rw-r--r--kernel/sysctl.c7
4 files changed, 44 insertions, 3 deletions
diff --git a/include/linux/sched/sysctl.h b/include/linux/sched/sysctl.h
index bac914e458ca..d2bb0ae979d0 100644
--- a/include/linux/sched/sysctl.h
+++ b/include/linux/sched/sysctl.h
@@ -73,6 +73,13 @@ static inline unsigned int get_sysctl_timer_migration(void)
return 1;
}
#endif
+
+/*
+ * control realtime throttling:
+ *
+ * /proc/sys/kernel/sched_rt_period_us
+ * /proc/sys/kernel/sched_rt_runtime_us
+ */
extern unsigned int sysctl_sched_rt_period;
extern int sysctl_sched_rt_runtime;
@@ -90,7 +97,13 @@ extern unsigned int sysctl_sched_autogroup_enabled;
*/
#define RR_TIMESLICE (100 * HZ / 1000)
-int sched_rt_handler(struct ctl_table *table, int write,
+extern int sched_rr_timeslice;
+
+extern int sched_rr_handler(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp,
+ loff_t *ppos);
+
+extern int sched_rt_handler(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp,
loff_t *ppos);
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 1dff78a9e2ab..4a88f1d51563 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7509,6 +7509,25 @@ static int sched_rt_global_constraints(void)
}
#endif /* CONFIG_RT_GROUP_SCHED */
+int sched_rr_handler(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp,
+ loff_t *ppos)
+{
+ int ret;
+ static DEFINE_MUTEX(mutex);
+
+ mutex_lock(&mutex);
+ ret = proc_dointvec(table, write, buffer, lenp, ppos);
+ /* make sure that internally we keep jiffies */
+ /* also, writing zero resets timeslice to default */
+ if (!ret && write) {
+ sched_rr_timeslice = sched_rr_timeslice <= 0 ?
+ RR_TIMESLICE : msecs_to_jiffies(sched_rr_timeslice);
+ }
+ mutex_unlock(&mutex);
+ return ret;
+}
+
int sched_rt_handler(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp,
loff_t *ppos)
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index c25de141c576..fb0f77e402b6 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -7,6 +7,8 @@
#include <linux/slab.h>
+int sched_rr_timeslice = RR_TIMESLICE;
+
static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
struct rt_bandwidth def_rt_bandwidth;
@@ -2016,7 +2018,7 @@ static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
if (--p->rt.time_slice)
return;
- p->rt.time_slice = RR_TIMESLICE;
+ p->rt.time_slice = sched_rr_timeslice;
/*
* Requeue to the end of queue if we (and all of our ancestors) are the
@@ -2047,7 +2049,7 @@ static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
* Time slice is 0 for SCHED_FIFO tasks
*/
if (task->policy == SCHED_RR)
- return RR_TIMESLICE;
+ return sched_rr_timeslice;
else
return 0;
}
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 7357e23aaf68..4fc9be955c71 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -404,6 +404,13 @@ static struct ctl_table kern_table[] = {
.mode = 0644,
.proc_handler = sched_rt_handler,
},
+ {
+ .procname = "sched_rr_timeslice_ms",
+ .data = &sched_rr_timeslice,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = sched_rr_handler,
+ },
#ifdef CONFIG_SCHED_AUTOGROUP
{
.procname = "sched_autogroup_enabled",