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SubjectRe: [PATCH] mm: vmscan: memcg: Add global shrink priority
Hi Hui,

teawater writes:
>Memory.min, low, high can affect the global shrink behavior. They can help
>task keep some pages to help protect performance.
>But what I want is the low priority tasks (the tasks that performance is not
>very important) do more shrink first. And when low priority tasks doesn’t
>have enough pages to be dropped and system need more free page, shrink the
>high priority task’s pages. Because at this time, system’s stable is more
>important than the performance of priority task.
>With memory.min and memory.low, I have no idea to config them to support this.
>That is why I add global shrink priority.

For sure, that's what I'm suggesting you use memory.{min,low} for -- you define
some subset of the cgroup hierarchy as "protected", and then you bias reclaim
away from protected cgroups (and thus *towards* unprotected cgroups) by biasing
the size of LRU scanning. See my patch that went into 5.4 and the examples in
the commit message:

commit 9783aa9917f8ae24759e67bf882f1aba32fe4ea1
Author: Chris Down <>
Date: Sun Oct 6 17:58:32 2019 -0700

mm, memcg: proportional memory.{low,min} reclaim

You can see how we're using memory.{low,min} to achieve this in this case
study[0]. It's not exactly equivalent technically to your solution, but the end
goals are similar.




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