Re: [RFC PATCH 0/8] memcg: Enable fine-grained per process memory control

[peterz]

On Tue, Aug 18, 2020 at 11:17:56AM +0100, Chris Down wrote:

> I'd ask that you understand a bit more about the tradeoffs and intentions of
> the patch before rushing in to declare its failure, considering it works
> just fine :-)
> 
> Clamping the maximal time allows the application to take some action to
> remediate the situation, while still being slowed down significantly. 2
> seconds per allocation batch is still absolutely plenty for any use case
> I've come across. If you have evidence it isn't, then present that instead
> of vague notions of "wrongness".

There is no feedback from the freeing rate, therefore it cannot be
correct in maintaining a maximum amount of pages.

0.5 pages / sec is still non-zero, and if the free rate is 0, you'll
crawl across whatever limit was set without any bounds. This is math
101.

It's true that I haven't been paying attention to mm in a while, but I
was one of the original authors of the I/O dirty balancing, I do think I
understand how these things work.