Messages in this thread Patch in this message | | | Date | Thu, 8 Nov 2012 19:51:13 -0600 | From | Clark Williams <> | Subject | [PATCH v2] sched: add a tuning knob to allow changing RR tmeslice |
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This version stores the user-input value in a separate location from the jiffies values used by the scheduler, to prevent a race condition.
Subject: [PATCH v2] sched: add a tuning knob to allow changing RR timeslice
User wanted a facility simliar to the ability on Solaris to adjust the SCHED_RR timeslice value. Add a /proc/sys/kernel scheduler knob named sched_rr_timeslice_ms which 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).
Patch against tip/master, currently 3.7-rc3.
Signed-off-by: Clark Williams <williams@redhat.com> --- include/linux/sched.h | 7 ++++++- kernel/sched/core.c | 30 ++++++++++++++++++++++++++++++ kernel/sched/rt.c | 4 ++-- kernel/sysctl.c | 7 +++++++ 4 files changed, 45 insertions(+), 3 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h index 03be150..1e2f38a 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2071,11 +2071,16 @@ static inline unsigned int get_sysctl_timer_migration(void) #endif /* CONFIG_SCHED_DEBUG */ extern unsigned int sysctl_sched_rt_period; extern int sysctl_sched_rt_runtime; - +extern int sysctl_sched_rr_timeslice_ms; +extern int sched_rr_timeslice; int sched_rt_handler(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos); +int sched_rr_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos); + #ifdef CONFIG_SCHED_AUTOGROUP extern unsigned int sysctl_sched_autogroup_enabled; diff --git a/kernel/sched/core.c b/kernel/sched/core.c index c2e077c..318f617 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -288,6 +288,17 @@ __read_mostly int scheduler_running; int sysctl_sched_rt_runtime = 950000; +/* + * SCHED_RR timeslice in jiffies + * + */ +int sched_rr_timeslice = RR_TIMESLICE; +int sysctl_sched_rr_timeslice_ms; + +static inline void init_rr_timeslice() +{ + sysctl_sched_rr_timeslice_ms = msecs_to_jiffies(RR_TIMESLICE); +} /* * __task_rq_lock - lock the rq @p resides on. @@ -6863,6 +6874,8 @@ void __init sched_init(void) init_rt_bandwidth(&def_rt_bandwidth, global_rt_period(), global_rt_runtime()); + init_rr_timeslice(); + #ifdef CONFIG_RT_GROUP_SCHED init_rt_bandwidth(&root_task_group.rt_bandwidth, global_rt_period(), global_rt_runtime()); @@ -7543,6 +7556,23 @@ int sched_rt_handler(struct ctl_table *table, int write, return ret; } +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 we maintain jiffies internally */ + if (!ret && write) + sched_rr_timeslice = (sysctl_sched_rr_timeslice_ms <= 0) ? + RR_TIMESLICE : msecs_to_jiffies(sysctl_sched_rr_timeslice_ms); + mutex_unlock(&mutex); + return ret; +} + #ifdef CONFIG_CGROUP_SCHED /* return corresponding task_group object of a cgroup */ diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 418feb0..71aa6d0 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -2010,7 +2010,7 @@ 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 @@ -2041,7 +2041,7 @@ 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 b769d25..9fa0885 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -403,6 +403,13 @@ static struct ctl_table kern_table[] = { .mode = 0644, .proc_handler = sched_rt_handler, }, + { + .procname = "sched_rr_timeslice_ms", + .data = &sysctl_sched_rr_timeslice_ms, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = sched_rr_handler, + }, #ifdef CONFIG_SCHED_AUTOGROUP { .procname = "sched_autogroup_enabled", -- 1.7.11.7 [unhandled content-type:application/pgp-signature]
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