Re: [PATCH 0/2] cgroup/dmem: introduce a peak file

[Michal Koutný]

On Wed, May 06, 2026 at 11:18:26AM -0300, Thadeu Lima de Souza Cascardo <cascardo@xxxxxxxxxx> wrote:
> I used void *, at first, but as the only current use is for the pool and as
> mixing different uses may lead to misuse, I thought it would be safer to
> use the type directly. This has been pointed out before for other members
> of cgroup_file_ctx. See [1].

That mail reacts to union overlaps and pointer vs embedded struct
allocations. Correct me if I missed your part.

I agree that having properly typed pointer is safer.
cgroup_file_ctx sub-structs are for generic cgroup files. But here
somehow a specific controller needs propagated to the generic member.

What about storing also the `list_head *watchers` inside `struct
cgroup_of_peak` and each subsys would manage it as needed?
(ofp->watchers == NULL could also substitute ofp->value ==
OFP_PEAK_UNSET)


> I started with a non-resettable peak file, but as memory.peak can be reset,
> I added that feature too. 

At the same time pids.peak has survived without reset option till today.

> If we want to merge a non-resettable support ealier and need to take
> longer to discuss how to work on the resettable support given the
> above, I can resubmit. But I guess we can see if we can reach an
> agreement sonner rather than later.

What kind of users do you envision (i.e. would they need resets at all)?
Anyway, the behavior should be explained in cgroup-v2.rst since that's
where they'll look for it.

HTH,
Michal

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