Setting the cpu affinity mask of a SCHED_DEADLINE process using the cgroup v1
cpuset controller is already detailed. Add similar information for cgroup v2's
cpuset controller.
Signed-off-by: Shashank Balaji <shashank.mahadasyam@xxxxxxxx>
---
Documentation/scheduler/sched-deadline.rst | 29 +++++++++++++++++++++++------
1 file changed, 23 insertions(+), 6 deletions(-)
diff --git a/Documentation/scheduler/sched-deadline.rst b/Documentation/scheduler/sched-deadline.rst
index a727827b8dd52710f880c2b92d3a8224c259873c..e3d7968ff6c3c43f87e249dbcb309619dbd616bf 100644
--- a/Documentation/scheduler/sched-deadline.rst
+++ b/Documentation/scheduler/sched-deadline.rst
@@ -20,7 +20,8 @@ Deadline Task Scheduling
4.3 Default behavior
4.4 Behavior of sched_yield()
5. Tasks CPU affinity
- 5.1 SCHED_DEADLINE and cpusets HOWTO
+ 5.1 Using cgroup v1 cpuset controller
+ 5.2 Using cgroup v2 cpuset controller
6. Future plans
A. Test suite
B. Minimal main()
@@ -671,12 +672,15 @@ Deadline Task Scheduling
5. Tasks CPU affinity
=====================
- -deadline tasks cannot have an affinity mask smaller that the entire
- root_domain they are created on. However, affinities can be specified
- through the cpuset facility (Documentation/admin-guide/cgroup-v1/cpusets.rst).
+ Deadline tasks cannot have a cpu affinity mask smaller than the root domain they
+ are created on. So, using ``sched_setaffinity(2)`` won't work. Instead, the
+ the deadline task should be created in a restricted root domain. This can be
+ done using the cpuset controller of either cgroup v1 (deprecated) or cgroup v2.
+ See :ref:`Documentation/admin-guide/cgroup-v1/cpusets.rst <cpusets>` and
+ :ref:`Documentation/admin-guide/cgroup-v2.rst <cgroup-v2>` for more information.
-5.1 SCHED_DEADLINE and cpusets HOWTO
-------------------------------------
+5.1 Using cgroup v1 cpuset controller
+-------------------------------------
An example of a simple configuration (pin a -deadline task to CPU0)
follows (rt-app is used to create a -deadline task)::
@@ -695,6 +699,19 @@ Deadline Task Scheduling
rt-app -t 100000:10000:d:0 -D5 # it is now actually superfluous to specify
# task affinity
+5.2 Using cgroup v2 cpuset controller
+-------------------------------------
+
+ Assuming the cgroup v2 root is mounted at ``/sys/fs/cgroup``.
+
+ cd /sys/fs/cgroup
+ echo '+cpuset' > cgroup.subtree_control
+ mkdir deadline_group
+ echo 0 > deadline_group/cpuset.cpus
+ echo 'root' > deadline_group/cpuset.cpus.partition
+ echo $$ > deadline_group/cgroup.procs
+ rt-app -t 100000:10000:d:0 -D5
+
6. Future plans
===============
---
base-commit: a5806cd506af5a7c19bcd596e4708b5c464bfd21
change-id: 20250522-sched-deadline-cpu-affinity-b0b4edf0ddc9
Best regards,
--
Shashank Balaji <shashank.mahadasyam@xxxxxxxx>
