[LTP] [PATCH] memcg_use_hierarchy_test.sh: skip setting use_hierarchy if not available

[Li Wang]

Chen, Hanxiao <chenhx.fnst@cn.fujitsu.com> wrote:

 *...*
>
> >@Li, I think this patch is ok, Do you have some comment about it?
>
> >
>
> >I'm ok to go with memory.use_hierarchy checking in the preconditioning
> phase.
>
> >
>
> >But how can you assert the default memory cgroup is mount at path:
> "/sys/fs/cgroup/memory", is there any possibility the default path mount at
> other places(for different distribution)?
>
>
>
>
> https://github.com/torvalds/linux/blob/b5fc7a89e58bcc059a3d5e4db79c481fb437de59/kernel/cgroup/cgroup.c#L5768
>
>
>
> WARN_ON(sysfs_create_mount_point(fs_kobj, "cgroup"));
>
>
>
> So the default mount place should be /sys/fs/cgroup if distributions
>
> did not modify these lines.
>
>
>
> As the discussion above,
>
> mount -t cgroup -omemory memcg /dev/memcg
>
> kernel will find a suitable cgroup root for us.
>
>
>
> How about reading /dev/memcg/memory.use_hierarchy as Yang recommended
> instead?
>

Sure.

But also, shouldn't we check if the '/dev/memcg' has sub-directory
before changing the memory.use_hiearchy in memcg_lib.sh?

As you noted in the description, enabling/disabling will fail if either
the cgroup already has other cgroups created below it.

-- 
Regards,
Li Wang
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