Re: [PATCH] mm, memcg: cg2 memory{.swap,}.peak write handlers

[Michal Hocko <mhocko@suse.com>]

On Tue 05-12-23 11:00:47, David Finkel wrote:
> On Tue, Dec 5, 2023 at 4:07 AM Michal Hocko <mhocko@suse.com> wrote:
> 
> > > This behavior is particularly useful for work scheduling systems that
> > > need to track memory usage of worker processes/cgroups per-work-item.
> > > Since memory can't be squeezed like CPU can (the OOM-killer has
> > > opinions), these systems need to track the peak memory usage to compute
> > > system/container fullness when binpacking workitems.
> >
> > I do not understand the OOM-killer reference here but I do understand
> > that your worker reuses a cgroup and you want a peak memory consumption
> > of a single run to better profile/configure the memcg configuration for
> > the specific worker type. Correct?
> 
> To a certain extent, yes.
> At the moment, we're only using the inner memcg cgroups for
> accounting/profiling, and using a
> larger (k8s container) cgroup for enforcement.
> 
> The OOM-killer is involved because we're not configuring any memory limits on
> these individual "worker" cgroups, so we need to provision for
> multiple workloads using
> their peak memory at the same time to minimize OOM-killing.

OK, that makes more sense now. Just be aware that you might under
utilize your limit that way because peak memory can still be reclaimed.
If you set the hard limit (memory.max) to the peak memory consumption
you would get a very conservative configuration wihtout any memory
reclaim.
 
> In case you're curious, this is the job/queue-work scheduling system
> we wrote in-house
> called Quickset that's mentioned in this blog post about our new
> transcoder system:
> https://medium.com/vimeo-engineering-blog/riding-the-dragon-e328a3dfd39d

Thanks!

-- 
Michal Hocko
SUSE Labs