2023-08-02 15:34:52

by Cyril Hrubis

Subject: [PATCH 2/2 RESEND] sched/rt: sysctl_sched_rr_timeslice show default timeslice after reset

The sched_rr_timeslice can be reset to default by writing value that is
<= 0. However after reading from this file we always got the last value
written, which is not useful at all.

$ echo -1 > /proc/sys/kernel/sched_rr_timeslice_ms
$ cat /proc/sys/kernel/sched_rr_timeslice_ms
-1

Fix this by setting the variable that holds the sysctl file value to the
jiffies_to_msecs(RR_TIMESLICE) in case that <= 0 value was written.

CC: Jiri Bohac <[email protected]>
Signed-off-by: Cyril Hrubis <[email protected]>
Acked-by: Mel Gorman <[email protected]>
Reviewed-by: Petr Vorel <[email protected]>
Tested-by: Petr Vorel <[email protected]>
---
kernel/sched/rt.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 185d3d749f6b..0597ba0f85ff 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -3062,6 +3062,9 @@ static int sched_rr_handler(struct ctl_table *table, int write, void *buffer,
sched_rr_timeslice =
sysctl_sched_rr_timeslice <= 0 ? RR_TIMESLICE :
msecs_to_jiffies(sysctl_sched_rr_timeslice);
+
+ if (sysctl_sched_rr_timeslice <= 0)
+ sysctl_sched_rr_timeslice = jiffies_to_msecs(RR_TIMESLICE);
}
mutex_unlock(&mutex);

--
2.41.0

2023-08-14 15:50:44

by tip-bot2 for Alexey Makhalov

Subject: [tip: sched/core] sched/rt: sysctl_sched_rr_timeslice show default timeslice after reset

The following commit has been merged into the sched/core branch of tip:

Commit-ID: c1fc6484e1fb7cc2481d169bfef129a1b0676abe
Gitweb: https://git.kernel.org/tip/c1fc6484e1fb7cc2481d169bfef129a1b0676abe
Author: Cyril Hrubis <[email protected]>
AuthorDate: Wed, 02 Aug 2023 17:19:06 +02:00
Committer: Peter Zijlstra <[email protected]>
CommitterDate: Mon, 14 Aug 2023 17:01:23 +02:00

sched/rt: sysctl_sched_rr_timeslice show default timeslice after reset

The sched_rr_timeslice can be reset to default by writing value that is
<= 0. However after reading from this file we always got the last value
written, which is not useful at all.

$ echo -1 > /proc/sys/kernel/sched_rr_timeslice_ms
$ cat /proc/sys/kernel/sched_rr_timeslice_ms
-1

Fix this by setting the variable that holds the sysctl file value to the
jiffies_to_msecs(RR_TIMESLICE) in case that <= 0 value was written.

Signed-off-by: Cyril Hrubis <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Petr Vorel <[email protected]>
Acked-by: Mel Gorman <[email protected]>
Tested-by: Petr Vorel <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
---
kernel/sched/rt.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 185d3d7..0597ba0 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -3062,6 +3062,9 @@ static int sched_rr_handler(struct ctl_table *table, int write, void *buffer,
sched_rr_timeslice =
sysctl_sched_rr_timeslice <= 0 ? RR_TIMESLICE :
msecs_to_jiffies(sysctl_sched_rr_timeslice);
+
+ if (sysctl_sched_rr_timeslice <= 0)
+ sysctl_sched_rr_timeslice = jiffies_to_msecs(RR_TIMESLICE);
}
mutex_unlock(&mutex);