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

[Michal Koutný]

Hello Thadeu.

On Wed, May 06, 2026 at 08:58:23AM -0300, Thadeu Lima de Souza Cascardo <cascardo@xxxxxxxxxx> wrote:
> Just like we have memory.peak, introduce a dmem.peak, which uses the
> page_counter support for that.
> 
> It can be written to in order to reset the peak, but different from
> memory.peak, which expects any write, dmem.peak expects the region name to
> be written to it. That region peak is the one that is reset.
> 
> That requires ofp_peak to carry a pointer to the pool that was reset.

(It'd be nicer to have generic data in that generic structure, at least
some void *priv. But see below.)

> Writing a different region name will reset the different region and make
> the original region peak get back to its non-reset value.

I'm slightly confused by this fds x pool matricity when there's only
a single slot in cgroup_file_ctx::cgroup_of_peak.

The intended use case is that users should maintain one fd per pool and
not mix it up?
This stanza would better fit to cgroup-v2.rst proper than the commit
message. Or make it simpler and start with non-resettable peak file
(like memory.peak had started too) and see how it fares. WDYT?


Thanks,
Michal

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