Re: [PATCH v6 10/19] mm: memcg/slab: deprecate memory.kmem.slabinfo

Shakeel Butt
2020-06-22T17:13:02Z

On Mon, Jun 8, 2020 at 4:07 PM Roman Gushchin <guro@fb.com> wrote:
>
> Deprecate memory.kmem.slabinfo.
>
> An empty file will be presented if corresponding config options are
> enabled.
>
> The interface is implementation dependent, isn't present in cgroup v2,
> and is generally useful only for core mm debugging purposes. In other
> words, it doesn't provide any value for the absolute majority of users.
>
> A drgn-based replacement can be found in tools/cgroup/slabinfo.py .
> It does support cgroup v1 and v2, mimics memory.kmem.slabinfo output
> and also allows to get any additional information without a need
> to recompile the kernel.
>
> If a drgn-based solution is too slow for a task, a bpf-based tracing
> tool can be used, which can easily keep track of all slab allocations
> belonging to a memory cgroup.
>
> Signed-off-by: Roman Gushchin <guro@fb.com>
> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
> Reviewed-by: Vlastimil Babka <vbabka@suse.cz>

Hi Roman,

I am not against removing the memory.kmem.slabinfo interface but I
would like to have an alternative solution more accessible than
tools/cgroup/slabinfo.py.

In our case, we don't have ssh access and if we need something for
debugging, it is much more preferable to provide a file to read to
SREs. After the review, that file will be added to a whitelist and
then we can directly read that file through automated tools without
approval for each request.

I am just wondering if a file interface can be provided for whatever
tools/cgroup/slabinfo.py is providing.

Shakeel