Re: [PATCH bpf-next 0/5] bpf: BPF specific memory allocator.

[Tejun Heo <tj@kernel.org>]

Hello,

On Tue, Jul 12, 2022 at 10:26:22AM -0700, Shakeel Butt wrote:
> One use-case we have is a build & test service which runs independent
> builds and tests but all the build utilities (compiler, linker,
> libraries) are shared between those builds and tests.
> 
> In terms of topology, the service has a top level cgroup (P) and all
> independent builds and tests run in their own cgroup under P. These
> builds/tests continuously come and go.
> 
> This service continuously monitors all the builds/tests running and
> may kill some based on some criteria which includes memory usage.
> However the memory usage is nondeterministic and killing a specific
> build/test may not really free memory if most of the memory charged to
> it is from shared build utilities.

That doesn't sound too unusual. So, one saving grace here is that the memory
pressure in the stressed cgroup should trigger reclaim of the shared memory
which will be likely picked up by someone else, hopefully, under less memory
pressure. Can you give more concerete details? ie. describe a failing
scenario with actual ballpark memory numbers?

FWIW, at least from generic resource constrol standpoint, I think it may
make sense to have a way to escape certain resources to an ancestor for
shared resources provided that we can come up with a sane interface.

Thanks.

-- 
tejun