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| author | Tiffany Yang <ynaffit@google.com> | 2025-08-21 18:37:52 -0700 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2025-08-22 07:50:43 -1000 |
| commit | afa3701c0e45ecb9e4d160048ca4e353c7489948 (patch) | |
| tree | 167bba9eec98ce9467b2e1d3aab6a5f67814c9af /Documentation/admin-guide | |
| parent | 4c70fb2624ab1588faa58dcd407d4c61d64b288d (diff) | |
cgroup: cgroup.stat.local time accounting
There isn't yet a clear way to identify a set of "lost" time that
everyone (or at least a wider group of users) cares about. However,
users can perform some delay accounting by iterating over components of
interest. This patch allows cgroup v2 freezing time to be one of those
components.
Track the cumulative time that each v2 cgroup spends freezing and expose
it to userland via a new local stat file in cgroupfs. Thank you to
Michal, who provided the ASCII art in the updated documentation.
To access this value:
$ mkdir /sys/fs/cgroup/test
$ cat /sys/fs/cgroup/test/cgroup.stat.local
freeze_time_total 0
Ensure consistent freeze time reads with freeze_seq, a per-cgroup
sequence counter. Writes are serialized using the css_set_lock.
Signed-off-by: Tiffany Yang <ynaffit@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'Documentation/admin-guide')
| -rw-r--r-- | Documentation/admin-guide/cgroup-v2.rst | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index d9d3cc7df348..9a3a909ee40b 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -1001,6 +1001,24 @@ All cgroup core files are prefixed with "cgroup." Total number of dying cgroup subsystems (e.g. memory cgroup) at and beneath the current cgroup. + cgroup.stat.local + A read-only flat-keyed file which exists in non-root cgroups. + The following entry is defined: + + frozen_usec + Cumulative time that this cgroup has spent between freezing and + thawing, regardless of whether by self or ancestor groups. + NB: (not) reaching "frozen" state is not accounted here. + + Using the following ASCII representation of a cgroup's freezer + state, :: + + 1 _____ + frozen 0 __/ \__ + ab cd + + the duration being measured is the span between a and c. + cgroup.freeze A read-write single value file which exists on non-root cgroups. Allowed values are "0" and "1". The default is "0". |