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

[Waiman Long <longman@redhat.com>]

On 8/17/20 12:56 PM, Chris Down wrote:
> Shakeel Butt writes:
>>> 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?
>
> Oh, thanks Shakeel for bringing this up. I missed this in the original 
> changelog and I'm surprised that it's mentioned, since we do have 
> protections against that.
>
> Waiman, we already added artificial throttling if memory reclaim is 
> not sufficiently achieved in 0e4b01df8659 ("mm, memcg: throttle 
> allocators when failing reclaim over memory.high"), which has been 
> present since v5.4. This should significantly inhibit physical memory 
> consumption from increasing. What problems are you having with that? :-)
>
Oh, I think I overlooked your patch. You are right. There are already 
throttling in place. So I need to re-examine my patch to see if it is 
still necessary or reduce the scope of the patch.

Thanks,
Longman