On 3/4/25 11:12 PM, Shashank Balaji via B4 Relay wrote:
From: Shashank Balaji <shashank.mahadasyam@xxxxxxxx>
If the cpu controller is enabled in a CONFIG_RT_GROUP_SCHED
disabled setting, cpu.stat and cpu.pressure account for realtime
processes, and cpu.uclamp.{min, max} affect realtime processes as well.
None of the other interface files are affected by or affect realtime
processes.
Signed-off-by: Shashank Balaji <shashank.mahadasyam@xxxxxxxx>
---
Documentation/admin-guide/cgroup-v2.rst | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index f293a13b42ed69e7c6bf5e974cb86e228411af4e..2c267f42e5fef9c4e2c3530ce73330d680b9b2dc 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -1095,7 +1095,9 @@ realtime processes irrespective of CONFIG_RT_GROUP_SCHED.
CPU Interface Files
~~~~~~~~~~~~~~~~~~~
-All time durations are in microseconds.
+All time durations are in microseconds. Only cpu.stat and cpu.pressure account
+for realtime processes, and only cpu.uclamp.min and cpu.uclamp.max
+affect realtime processes.
cpu.stat
A read-only flat-keyed file.
@@ -1115,6 +1117,9 @@ All time durations are in microseconds.
- nr_bursts
- burst_usec
+ The runtime of realtime processes is accounted for only by the usage_usec,
+ user_usec, and system_usec fields.
+
Alignment problem!
Anyway, I am not familiar enough with these cpu control files to give a
review yet.
Cheers,
Longman
cpu.weight
A read-write single value file which exists on non-root
cgroups. The default is "100".
@@ -1158,8 +1163,9 @@ All time durations are in microseconds.
cpu.pressure
A read-write nested-keyed file.
- Shows pressure stall information for CPU. See
- :ref:`Documentation/accounting/psi.rst <psi>` for details.
+ Shows pressure stall information for CPU, including the contribution of
+ realtime processes. See :ref:`Documentation/accounting/psi.rst <psi>`
+ for details.
cpu.uclamp.min
A read-write single value file which exists on non-root cgroups.
@@ -1170,7 +1176,8 @@ All time durations are in microseconds.
This interface allows reading and setting minimum utilization clamp
values similar to the sched_setattr(2). This minimum utilization
- value is used to clamp the task specific minimum utilization clamp.
+ value is used to clamp the task specific minimum utilization clamp,
+ including those of realtime processes.
The requested minimum utilization (protection) is always capped by
the current value for the maximum utilization (limit), i.e.
@@ -1185,7 +1192,8 @@ All time durations are in microseconds.
This interface allows reading and setting maximum utilization clamp
values similar to the sched_setattr(2). This maximum utilization
- value is used to clamp the task specific maximum utilization clamp.
+ value is used to clamp the task specific maximum utilization clamp,
+ including those of realtime processes.
cpu.idle
A read-write single value file which exists on non-root cgroups.
