Re: [PATCH v7 00/12] Support non-lru page migration

From: Andrew Morton
Date: Wed Jun 01 2016 - 17:41:58 EST

On Wed, 1 Jun 2016 08:21:09 +0900 Minchan Kim <minchan@xxxxxxxxxx> wrote:

> Recently, I got many reports about perfermance degradation in embedded
> system(Android mobile phone, webOS TV and so on) and easy fork fail.
> The problem was fragmentation caused by zram and GPU driver mainly.
> With memory pressure, their pages were spread out all of pageblock and
> it cannot be migrated with current compaction algorithm which supports
> only LRU pages. In the end, compaction cannot work well so reclaimer
> shrinks all of working set pages. It made system very slow and even to
> fail to fork easily which requires order-[2 or 3] allocations.
> Other pain point is that they cannot use CMA memory space so when OOM
> kill happens, I can see many free pages in CMA area, which is not
> memory efficient. In our product which has big CMA memory, it reclaims
> zones too exccessively to allocate GPU and zram page although there are
> lots of free space in CMA so system becomes very slow easily.

But this isn't presently implemented for GPU drivers or for CMA, yes?

What's the story there?