cgroup: call subsys->*attach() only for subsystems which are actually affected by migration

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Currently, subsys->*attach() callbacks are called for all subsystems
which are attached to the hierarchy on which the migration is taking
place.

With cgroup_migrate_prepare_dst() filtering out identity migrations,
v1 hierarchies can avoid spurious ->*attach() callback invocations
where the source and destination csses are identical; however, this
isn't enough on v2 as only a subset of the attached controllers can be
affected on controller enable/disable.

While spurious ->*attach() invocations aren't critically broken,
they're unnecessary overhead and can lead to temporary overcharges on
certain controllers.  Fix it by tracking which subsystems are affected
by a migration and invoking ->*attach() callbacks only on those
subsystems.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>

...

This commit is contained in:

Tejun Heo 2017-01-15 19:03:41 -05:00

parent e595cd7069

commit bfc2cf6f61

3 changed files with 19 additions and 13 deletions

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5

kernel/cgroup/cgroup-internal.h

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2

kernel/cgroup/cgroup-v1.c

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25

kernel/cgroup/cgroup.c

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