Re: [PATCH] kernel/cgroup/pids: add "pids.forks" counter

[Michal Koutný]

On Fri, May 02, 2025 at 03:23:26PM +0200, Max Kellermann <max.kellermann@xxxxxxxxx> wrote:
> Sure you can do everything with BPF, but that's several magnitudes
> more overhead (if you worry about the atomic operation in my patch).

I worried about users that don't need the counter ;-)


> we want to monitor all servers permanently and log every counter of
> every cgroup.

OK, I assumed the process "clock" is only useful transiently for
debugging...

> Later, if we see (performance) problems, we can reconstruct from those
> logs what/who may have caused them. The fork counter is an interesting
> detail for this.

...since it's more of a proxy measure over other cummulative stats that
are bound to actual resources like cpu time or vmstat:pgalloc* [1].

> It's very useful for us and that justifies the (small) memory+atomic
> overhead, but others may have a different opinion. If you don't find
> it useful, we'll just keep the patch in our private kernel fork (like
> dozens of others).

OK, let's see if someone else finds it so useful too. Definitely thanks
for putting it forward as first.

Michal

[1] This is actually something that I find missing for memcgs.

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