The following commit has been merged into the sched/urgent branch of tip: Commit-ID: b1536481c81fb604074da799e4f2d2038a1663f7 Gitweb: https://git.kernel.org/tip/b1536481c81fb604074da799e4f2d2038a1663f7 Author: Shrikanth Hegde <sshegde@xxxxxxxxxxxxx> AuthorDate: Thu, 06 Mar 2025 10:59:54 +05:30 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Thu, 06 Mar 2025 10:21:31 +01:00 sched/rt: Update limit of sched_rt sysctl in documentation By default fair_server dl_server allocates 5% of the bandwidth to the root domain. Due to this writing any value less than 5% fails due to -EBUSY: $ cat /proc/sys/kernel/sched_rt_period_us 1000000 $ echo 49999 > /proc/sys/kernel/sched_rt_runtime_us -bash: echo: write error: Device or resource busy $ echo 50000 > /proc/sys/kernel/sched_rt_runtime_us $ Since the sched_rt_runtime_us allows -1 as the minimum, put this restriction in the documentation. One should check average of runtime/period in /sys/kernel/debug/sched/fair_server/cpuX/* for exact value. Signed-off-by: Shrikanth Hegde <sshegde@xxxxxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Reviewed-by: Juri Lelli <juri.lelli@xxxxxxxxxx> Link: https://lore.kernel.org/r/20250306052954.452005-3-sshegde@xxxxxxxxxxxxx --- Documentation/scheduler/sched-rt-group.rst | 3 +++ 1 file changed, 3 insertions(+) diff --git a/Documentation/scheduler/sched-rt-group.rst b/Documentation/scheduler/sched-rt-group.rst index 80b05a3..ab46433 100644 --- a/Documentation/scheduler/sched-rt-group.rst +++ b/Documentation/scheduler/sched-rt-group.rst @@ -102,6 +102,9 @@ The system wide settings are configured under the /proc virtual file system: * sched_rt_period_us takes values from 1 to INT_MAX. * sched_rt_runtime_us takes values from -1 to sched_rt_period_us. * A run time of -1 specifies runtime == period, ie. no limit. + * sched_rt_runtime_us/sched_rt_period_us > 0.05 inorder to preserve + bandwidth for fair dl_server. For accurate value check average of + runtime/period in /sys/kernel/debug/sched/fair_server/cpuX/ 2.2 Default behaviour
|