On Wed, 23 Jan 2013 15:09:38 -0500 Steven Rostedt <[email protected]> wrote:
> On Thu, 2012-11-08 at 14:27 -0600, Clark Williams wrote: > > Subject: [PATCH] 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). > > > > Hmm, has this been ignored? > > I guess the real question, is it still needed (or wanted)? > Yes, we've got a couple of customers that have been asking for it. > -- Steve > > > Patch against tip/master, currently 3.7-rc3. > > > > Signed-off-by: Clark Williams <[email protected]> > > --- > > include/linux/sched.h | 6 +++++- > > kernel/sched.c | 19 +++++++++++++++++++ > > kernel/sched_rt.c | 4 ++-- > > kernel/sysctl.c | 8 ++++++++ > > 4 files changed, 34 insertions(+), 3 deletions(-) > > > > diff --git a/include/linux/sched.h b/include/linux/sched.h > > index 12317b6..214bf27 100644 > > --- a/include/linux/sched.h > > +++ b/include/linux/sched.h > > @@ -2097,11 +2097,15 @@ static inline unsigned int > > get_sysctl_timer_migration(void) > > #endif > > extern unsigned int sysctl_sched_rt_period; > > extern int sysctl_sched_rt_runtime; > > - > > int sched_rt_handler(struct ctl_table *table, int write, > > void __user *buffer, size_t *lenp, > > loff_t *ppos); > > > > +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); > > + > > #ifdef CONFIG_SCHED_AUTOGROUP > > extern unsigned int sysctl_sched_autogroup_enabled; > > > > diff --git a/kernel/sched.c b/kernel/sched.c > > index cdf9484..c63c3a4 100644 > > --- a/kernel/sched.c > > +++ b/kernel/sched.c > > @@ -120,6 +120,7 @@ > > * Timeslices get refilled after they expire. > > */ > > #define DEF_TIMESLICE (100 * HZ / 1000) > > +int sched_rr_timeslice = DEF_TIMESLICE; > > > > /* > > * single value that denotes runtime == period, ie unlimited time. > > @@ -9614,6 +9615,24 @@ 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 ? > > + DEF_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 c108b9c..799dd09 100644 > > --- a/kernel/sched_rt.c > > +++ b/kernel/sched_rt.c > > @@ -1791,7 +1791,7 @@ static void task_tick_rt(struct rq *rq, struct > > task_struct *p, int queued) > > if (--p->rt.time_slice) > > return; > > > > - p->rt.time_slice = DEF_TIMESLICE; > > + p->rt.time_slice = sched_rr_timeslice; > > > > /* > > * Requeue to the end of queue if we are not the only element > > @@ -1819,7 +1819,7 @@ 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 DEF_TIMESLICE; > > + return sched_rr_timeslice; > > else > > return 0; > > } > > diff --git a/kernel/sysctl.c b/kernel/sysctl.c > > index ea7ec7f..10b1129 100644 > > --- a/kernel/sysctl.c > > +++ b/kernel/sysctl.c > > @@ -362,6 +362,14 @@ 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", > >
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