Hi Michal,

On Tue, Aug 11, 2020 at 10:36 AM Michal Koutn√Ω [off-list ref] wrote:

Hi Shakeel.

On Tue, Jul 07, 2020 at 10:02:50AM -0700, Shakeel Butt [off-list ref] wrote:

quoted

quoted

Well, I was talkingg about memory.low. It is not meant only to protect
from the global reclaim. It can be used for balancing memory reclaim
from _any_ external memory pressure source. So it is somehow related to
the usecase you have mentioned.

For the uswapd use-case, I am not concerned about the external memory
pressure source but the application hitting its own memory.high limit
and getting throttled.

FTR, you can transform own memory.high into "external" pressure with a
hierarchy such as

  limit-group                   memory.high=N+margin memory.low=0
  `- latency-sensitive-group    memory.low=N
  `- regular-group              memory.low=0

Would that ensure the latency targets?

My concern was not "whom to reclaim from" but it was "If I use
memory.high for reclaim, processes running in that memcg can hit
memory.high and get throttled". However Roman has reduced the window
where that can happen. Anyways I will send the next version after this
merge window closes.

Shakeel