Re: [External] Re: [PATCH] mm/memcontrol: Add the drop_cache interface for cgroup v2

[Chris Down]

Chunxin Zang writes:
> My usecase is that there are two types of services in one server. They
> have difference
> priorities. Type_A has the highest priority, we need to ensure it's
> schedule latency、I/O
> latency、memory enough. Type_B has the lowest priority, we expect it
> will not affect
> Type_A when executed.
> So Type_A could use memory without any limit. Type_B could use memory
> only when the
> memory is absolutely sufficient. But we cannot estimate how much
> memory Type_B should
> use. Because everything is dynamic. So we can't set Type_B's memory.high.
>
> So we want to release the memory of Type_B when global memory is
> insufficient in order
> to ensure the quality of service of Type_A . In the past, we used the
> 'force_empty' interface
> of cgroup v1.

This sounds like a perfect use case for memory.low on Type_A, and it's pretty 
much exactly what we invented it for. What's the problem with that?