Re: High kmalloc-32 slab cache consumption with 10k containers

[Christian Brauner]

On Wed, Apr 07, 2021 at 01:54:48PM +0200, Michal Hocko wrote:
> On Mon 05-04-21 11:18:48, Bharata B Rao wrote:
> > Hi,
> > 
> > When running 10000 (more-or-less-empty-)containers on a bare-metal Power9
> > server(160 CPUs, 2 NUMA nodes, 256G memory), it is seen that memory
> > consumption increases quite a lot (around 172G) when the containers are
> > running. Most of it comes from slab (149G) and within slab, the majority of
> > it comes from kmalloc-32 cache (102G)
> 
> Is this 10k cgroups a testing enviroment or does anybody really use that
> in production? I would be really curious to hear how that behaves when
> those containers are not idle. E.g. global memory reclaim iterating over
> 10k memcgs will likely be very visible. I do remember playing with
> similar setups few years back and the overhead was very high.

Ccing Stéphane Graber who has experience/insight about stuff like this.

Christian