Re: [PATCH v2 00/18] Support non-lru page migration

Minchan Kim
2016-03-28T05:07:14Z

Hello Andrew,

On Mon, Mar 21, 2016 at 03:30:49PM +0900, Minchan Kim wrote:
> Recently, I got many reports about perfermance degradation
> in embedded system(Android mobile phone, webOS TV and so on)
> and failed to fork easily.
>
> The problem was fragmentation caused by zram and GPU driver
> pages. Their pages cannot be migrated so compaction cannot
> work well, either so reclaimer ends up shrinking all of working
> set pages. It made system very slow and even to fail to fork
> easily.
>
> Other pain point is that they cannot work with CMA.
> Most of CMA memory space could be idle(ie, it could be used
> for movable pages unless driver is using) but if driver(i.e.,
> zram) cannot migrate his page, that memory space could be
> wasted. In our product which has big CMA memory, it reclaims
> zones too exccessively although there are lots of free space
> in CMA so system was very slow easily.
>
> To solve these problem, this patch try to add facility to
> migrate non-lru pages via introducing new friend functions
> of migratepage in address_space_operation and new page flags.
>
> (isolate_page, putback_page)
> (PG_movable, PG_isolated)
>
> For details, please read description in
> "mm/compaction: support non-lru movable page migration".
>
> Originally, Gioh Kim tried to support this feature but he moved
> so I took over the work. But I took many code from his work and
> changed a little bit.
> Thanks, Gioh!
>
> And I should mention Konstantin Khlebnikov. He really heped Gioh
> at that time so he should deserve to have many credit, too.
> Thanks, Konstantin!
>
> This patchset consists of five parts
>
> 1. clean up migration
> mm: use put_page to free page instead of putback_lru_page
>
> 2. zsmalloc clean-up for preparing page migration
> zsmalloc: use first_page rather than page
> zsmalloc: clean up many BUG_ON
> zsmalloc: reordering function parameter
> zsmalloc: remove unused pool param in obj_free
> zsmalloc: keep max_object in size_class
> zsmalloc: squeeze inuse into page->mapping
> zsmalloc: squeeze freelist into page->mapping
> zsmalloc: move struct zs_meta from mapping to freelist
> zsmalloc: factor page chain functionality out
> zsmalloc: separate free_zspage from putback_zspage
> zsmalloc: zs_compact refactoring

In this series, [2-5] are clean up regardless of goal of the patchset
so it could be merged independently.
I want to reduce patchset size in next post.
If anyone are not against, could you merge cleanup patchset?

zsmalloc: use first_page rather than page
zsmalloc: clean up many BUG_ON
zsmalloc: reordering function parameter
zsmalloc: remove unused pool param in obj_free

Thanks.