On Tue 03-11-20 13:27:24, Roman Gushchin wrote: > Update cgroup v1 docs after the deprecation of the non-hierarchical > mode of the memory controller. > > Signed-off-by: Roman Gushchin <guro@xxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> > --- > .../admin-guide/cgroup-v1/memcg_test.rst | 8 ++-- > .../admin-guide/cgroup-v1/memory.rst | 40 ++++++------------- > 2 files changed, 16 insertions(+), 32 deletions(-) > > diff --git a/Documentation/admin-guide/cgroup-v1/memcg_test.rst b/Documentation/admin-guide/cgroup-v1/memcg_test.rst > index 3f7115e07b5d..4f83de2dab6e 100644 > --- a/Documentation/admin-guide/cgroup-v1/memcg_test.rst > +++ b/Documentation/admin-guide/cgroup-v1/memcg_test.rst > @@ -219,13 +219,11 @@ Under below explanation, we assume CONFIG_MEM_RES_CTRL_SWAP=y. > > This is an easy way to test page migration, too. > > -9.5 mkdir/rmdir > ---------------- > +9.5 nested cgroups > +------------------ > > - When using hierarchy, mkdir/rmdir test should be done. > - Use tests like the following:: > + Use tests like the following for testing nested cgroups:: > > - echo 1 >/opt/cgroup/01/memory/use_hierarchy > mkdir /opt/cgroup/01/child_a > mkdir /opt/cgroup/01/child_b > > diff --git a/Documentation/admin-guide/cgroup-v1/memory.rst b/Documentation/admin-guide/cgroup-v1/memory.rst > index 12757e63b26c..a44cd467d218 100644 > --- a/Documentation/admin-guide/cgroup-v1/memory.rst > +++ b/Documentation/admin-guide/cgroup-v1/memory.rst > @@ -77,6 +77,8 @@ Brief summary of control files. > memory.soft_limit_in_bytes set/show soft limit of memory usage > memory.stat show various statistics > memory.use_hierarchy set/show hierarchical account enabled > + This knob is deprecated and shouldn't be > + used. > memory.force_empty trigger forced page reclaim > memory.pressure_level set memory pressure notifications > memory.swappiness set/show swappiness parameter of vmscan > @@ -495,16 +497,13 @@ cgroup might have some charge associated with it, even though all > tasks have migrated away from it. (because we charge against pages, not > against tasks.) > > -We move the stats to root (if use_hierarchy==0) or parent (if > -use_hierarchy==1), and no change on the charge except uncharging > +We move the stats to parent, and no change on the charge except uncharging > from the child. > > Charges recorded in swap information is not updated at removal of cgroup. > Recorded information is discarded and a cgroup which uses swap (swapcache) > will be charged as a new owner of it. > > -About use_hierarchy, see Section 6. > - > 5. Misc. interfaces > =================== > > @@ -527,8 +526,6 @@ About use_hierarchy, see Section 6. > write will still return success. In this case, it is expected that > memory.kmem.usage_in_bytes == memory.usage_in_bytes. > > - About use_hierarchy, see Section 6. > - > 5.2 stat file > ------------- > > @@ -675,31 +672,20 @@ hierarchy:: > d e > > In the diagram above, with hierarchical accounting enabled, all memory > -usage of e, is accounted to its ancestors up until the root (i.e, c and root), > -that has memory.use_hierarchy enabled. If one of the ancestors goes over its > -limit, the reclaim algorithm reclaims from the tasks in the ancestor and the > -children of the ancestor. > - > -6.1 Enabling hierarchical accounting and reclaim > ------------------------------------------------- > - > -A memory cgroup by default disables the hierarchy feature. Support > -can be enabled by writing 1 to memory.use_hierarchy file of the root cgroup:: > +usage of e, is accounted to its ancestors up until the root (i.e, c and root). > +If one of the ancestors goes over its limit, the reclaim algorithm reclaims > +from the tasks in the ancestor and the children of the ancestor. > > - # echo 1 > memory.use_hierarchy > - > -The feature can be disabled by:: > +6.1 Hierarchical accounting and reclaim > +--------------------------------------- > > - # echo 0 > memory.use_hierarchy > +Hierarchical accounting is enabled by default. Disabling the hierarchical > +accounting is deprecated. An attempt to do it will result in a failure > +and a warning printed to dmesg. > > -NOTE1: > - Enabling/disabling will fail if either the cgroup already has other > - cgroups created below it, or if the parent cgroup has use_hierarchy > - enabled. > +For compatibility reasons writing 1 to memory.use_hierarchy will always pass:: > > -NOTE2: > - When panic_on_oom is set to "2", the whole system will panic in > - case of an OOM event in any cgroup. > + # echo 1 > memory.use_hierarchy > > 7. Soft limits > ============== > -- > 2.26.2 -- Michal Hocko SUSE Labs
