sched/rt/docs: Clarify & fix sched_rt_* sysctl docs

[sfrench/cifs-2.6.git] / Documentation / scheduler / sched-rt-group.rst

diff --git a/Documentation/scheduler/sched-rt-group.rst b/Documentation/scheduler/sched-rt-group.rst
index 655a096ec8fbdf5accd524a1a2ddc67ee57a89c7..a16bee8f74c247d00f5fa4611293576c8aa54cff 100644 (file)
--- a/Documentation/scheduler/sched-rt-group.rst
+++ b/Documentation/scheduler/sched-rt-group.rst
@@ -87,18 +87,20 @@ lack an EDF scheduler to make non-uniform periods usable.
 The system wide settings are configured under the /proc virtual file system:
 
 /proc/sys/kernel/sched_rt_period_us:
-  The scheduling period that is equivalent to 100% CPU bandwidth
+  The scheduling period that is equivalent to 100% CPU bandwidth.
 
 /proc/sys/kernel/sched_rt_runtime_us:
-  A global limit on how much time realtime scheduling may use.  Even without
-  CONFIG_RT_GROUP_SCHED enabled, this will limit time reserved to realtime
-  processes. With CONFIG_RT_GROUP_SCHED it signifies the total bandwidth
-  available to all realtime groups.
+  A global limit on how much time realtime scheduling may use. This is always
+  less or equal to the period_us, as it denotes the time allocated from the
+  period_us for the realtime tasks. Even without CONFIG_RT_GROUP_SCHED enabled,
+  this will limit time reserved to realtime processes. With
+  CONFIG_RT_GROUP_SCHED=y it signifies the total bandwidth available to all
+  realtime groups.
 
   * Time is specified in us because the interface is s32. This gives an
     operating range from 1us to about 35 minutes.
   * sched_rt_period_us takes values from 1 to INT_MAX.
-  * sched_rt_runtime_us takes values from -1 to (INT_MAX - 1).
+  * sched_rt_runtime_us takes values from -1 to sched_rt_period_us.
   * A run time of -1 specifies runtime == period, ie. no limit.