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sched/rt: Show the 'sched_rr_timeslice' SCHED_RR timeslice tuning knob in milliseconds 

We added the 'sched_rr_timeslice_ms' SCHED_RR tuning knob in this commit:

  ce0dbbbb30 ("sched/rt: Add a tuning knob to allow changing SCHED_RR timeslice")

... which name suggests to users that it's in milliseconds, while in reality
it's being set in milliseconds but the result is shown in jiffies.

This is obviously confusing when HZ is not 1000, it makes it appear like the
value set failed, such as HZ=100:

  root# echo 100 > /proc/sys/kernel/sched_rr_timeslice_ms
  root# cat /proc/sys/kernel/sched_rr_timeslice_ms
  10

Fix this to be milliseconds all around.

Signed-off-by: Shile Zhang <shile.zhang@nokia.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1485612049-20923-1-git-send-email-shile.zhang@nokia.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Shile Zhang 2017-01-28 22:00:49 +08:00 committed by Ingo Molnar
parent 733ce725aa
commit 975e155ed8
4 changed files with 6 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/sched/sysctl.h
View File

@ -59,6 +59,7 @@ extern unsigned int sysctl_sched_cfs_bandwidth_slice;
extern unsigned int sysctl_sched_autogroup_enabled;
#endif
extern int sysctl_sched_rr_timeslice;
extern int sched_rr_timeslice;
extern int sched_rr_handler(struct ctl_table *table, int write,

5
kernel/sched/core.c
View File

@ -8471,8 +8471,9 @@ int sched_rr_handler(struct ctl_table *table, int write,
/* 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);
sched_rr_timeslice =
sysctl_sched_rr_timeslice <= 0 ? RR_TIMESLICE :
msecs_to_jiffies(sysctl_sched_rr_timeslice);
}
mutex_unlock(&mutex);
return ret;

1
kernel/sched/rt.c
View File

@ -9,6 +9,7 @@
#include <linux/irq_work.h>
int sched_rr_timeslice = RR_TIMESLICE;
int sysctl_sched_rr_timeslice = (MSEC_PER_SEC / HZ) * RR_TIMESLICE;
static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);

2
kernel/sysctl.c
View File

@ -416,7 +416,7 @@ static struct ctl_table kern_table[] = {
},
{
.procname = "sched_rr_timeslice_ms",
.data = &sched_rr_timeslice,
.data = &sysctl_sched_rr_timeslice,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = sched_rr_handler,