Re: [PATCH v4 00/13] Support non-lru page migration

[Minchan Kim]

Hello Andrew,

On Wed, Apr 27, 2016 at 01:20:35PM -0700, Andrew Morton wrote:
> On Wed, 27 Apr 2016 16:48:13 +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.
> > 
> > To solve these problem, this patch tries to add facility to migrate
> > non-lru pages via introducing new functions and page flags to help
> > migration.
> 
> I'm seeing some rejects here against Mel's changes and our patch
> bandwidth is getting waaay way ahead of our review bandwidth.  So I
> think I'll loadshed this patchset at this time, sorry.

I expected the conflict with Mel's change in recent mmotm but doesn't want
to send patches against recent mmotm because it has several problems in
compaction so my test was really trobule.
I just picked patches from Hugh and Vlastimil and finally can test on it.
Anyway, I will rebase my patches on recent mmotm, hoping you picked every
patches on compaction part and respin after a few days.

Thanks for let me knowing your plan.