1. Instead of enabling all available controllers, figure out which
ones are required, and only enable those.
2. Amend all setFoo() functions to call isFooSet(). While this might
seem unnecessary, it might actually help to uncover a bug.
Imagine someone:
- adds a cgroup.Resources.CpuFoo setting;
- modifies setCpu() to apply the new setting;
- but forgets to amend isCpuSet() accordingly <-- BUG
In this case, a test case modifying CpuFoo will help
to uncover the BUG. This is the reason why it's added.
This patch *could be* amended by enabling controllers on a best-effort
basis, i.e. :
- do not return an error early if we can't enable some controllers;
- if we fail to enable all controllers at once (usually because one
of them can't be enabled), try enabling them one by one.
Currently this is not implemented, and it's not clear whether this
would be a good way to go or not.
[v2: add/use is${Controller}Set() functions]
[v3: document neededControllers()]
[v4: drop "best-effort" part]
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
This check was removed in commit 5406833a65. Now, when this
function is called from a few places, it is no longer obvious
that the path always starts with /sys/fs/cgroup/, so reinstate
the check just to be on the safe side.
This check also ensures that elements[3:] can be used safely.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
fs2 cgroup driver was not working because it did not enable controllers
while creating cgroup directory; instead it was merely doing MkdirAll()
and gathered the list of available controllers in NewManager().
Also, cgroup should be created in Apply(), not while creating a new
manager instance.
To fix:
1. Move the createCgroupsv2Path function from systemd driver to fs2 driver,
renaming it to CreateCgroupPath. Use in Apply() from both fs2 and
systemd drivers.
2. Delay available controllers map initialization to until it is needed.
With this patch:
- NewManager() only performs minimal initialization (initializin
m.dirPath, if not provided);
- Apply() properly creates cgroup path, enabling the controllers;
- m.controllers is initialized lazily on demand.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Kir Kolyshkin