Merge tag 'block-5.14-2021-08-07' of git://git.kernel.dk/linux-block

[linux-2.6-microblaze.git] / Documentation / admin-guide / cgroup-v2.rst

diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index b1e81aa..5c7377b 100644 (file)
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -56,6 +56,7 @@ v1 is available under :ref:`Documentation/admin-guide/cgroup-v1/index.rst <cgrou
        5-3-3. IO Latency
          5-3-3-1. How IO Latency Throttling Works
          5-3-3-2. IO Latency Interface Files
        5-3-3. IO Latency
          5-3-3-1. How IO Latency Throttling Works
          5-3-3-2. IO Latency Interface Files

+       5-3-4. IO Priority

      5-4. PID
        5-4-1. PID Interface Files
      5-5. Cpuset
      5-4. PID
        5-4-1. PID Interface Files
      5-5. Cpuset


@@ -952,6 +953,21 @@ All cgroup core files are prefixed with "cgroup."
        it's possible to delete a frozen (and empty) cgroup, as well as
        create new sub-cgroups.
 
        it's possible to delete a frozen (and empty) cgroup, as well as
        create new sub-cgroups.
 

+  cgroup.kill
+       A write-only single value file which exists in non-root cgroups.
+       The only allowed value is "1".
+
+       Writing "1" to the file causes the cgroup and all descendant cgroups to
+       be killed. This means that all processes located in the affected cgroup
+       tree will be killed via SIGKILL.
+
+       Killing a cgroup tree will deal with concurrent forks appropriately and
+       is protected against migrations.
+
+       In a threaded cgroup, writing this file fails with EOPNOTSUPP as
+       killing cgroups is a process directed operation, i.e. it affects
+       the whole thread-group.
+

 Controllers
 ===========
 
 Controllers
 ===========
 


@@ -1866,6 +1882,60 @@ IO Latency Interface Files
                duration of time between evaluation events.  Windows only elapse
                with IO activity.  Idle periods extend the most recent window.
 
                duration of time between evaluation events.  Windows only elapse
                with IO activity.  Idle periods extend the most recent window.
 

+IO Priority
+~~~~~~~~~~~
+
+A single attribute controls the behavior of the I/O priority cgroup policy,
+namely the blkio.prio.class attribute. The following values are accepted for
+that attribute:
+
+  no-change
+       Do not modify the I/O priority class.
+
+  none-to-rt
+       For requests that do not have an I/O priority class (NONE),
+       change the I/O priority class into RT. Do not modify
+       the I/O priority class of other requests.
+
+  restrict-to-be
+       For requests that do not have an I/O priority class or that have I/O
+       priority class RT, change it into BE. Do not modify the I/O priority
+       class of requests that have priority class IDLE.
+
+  idle
+       Change the I/O priority class of all requests into IDLE, the lowest
+       I/O priority class.
+
+The following numerical values are associated with the I/O priority policies:
+
++-------------+---+
+| no-change   | 0 |
++-------------+---+
+| none-to-rt  | 1 |
++-------------+---+
+| rt-to-be    | 2 |
++-------------+---+
+| all-to-idle | 3 |
++-------------+---+
+
+The numerical value that corresponds to each I/O priority class is as follows:
+
++-------------------------------+---+
+| IOPRIO_CLASS_NONE             | 0 |
++-------------------------------+---+
+| IOPRIO_CLASS_RT (real-time)   | 1 |
++-------------------------------+---+
+| IOPRIO_CLASS_BE (best effort) | 2 |
++-------------------------------+---+
+| IOPRIO_CLASS_IDLE             | 3 |
++-------------------------------+---+
+
+The algorithm to set the I/O priority class for a request is as follows:
+
+- Translate the I/O priority class policy into a number.
+- Change the request I/O priority class into the maximum of the I/O priority
+  class policy number and the numerical I/O priority class.
+

 PID
 ---
 
 PID
 ---