Re: [RFC PATCH 1/8] memcg: Enable fine-grained control of over memory.high action

[Waiman Long <longman@redhat.com>]

On 8/17/20 12:44 PM, Shakeel Butt wrote:
> On Mon, Aug 17, 2020 at 7:11 AM Waiman Long <longman@redhat.com> wrote:
>> Memory controller can be used to control and limit the amount of
>> physical memory used by a task. When a limit is set in "memory.high"
>> in a non-root memory cgroup, the memory controller will try to reclaim
>> memory if the limit has been exceeded. Normally, that will be enough
>> to keep the physical memory consumption of tasks in the memory cgroup
>> to be around or below the "memory.high" limit.
>>
>> Sometimes, memory reclaim may not be able to recover memory in a rate
>> that can catch up to the physical memory allocation rate especially
>> when rotating disks are used for swapping or writing dirty pages. In
>> this case, the physical memory consumption will keep on increasing.
> Isn't this the real underlying issue? Why not make the guarantees of
> memory.high more strict instead of adding more interfaces and
> complexity?
>
> By the way, have you observed this issue on real workloads or some
> test cases? It would be good to get a repro with simple test cases.
>
As said before, this is from a customer request. I will need to 
re-examine the existing features to see if they can satisfy the customer 
need.

Cheers,
Longman