[Devel] Re: memrlimit controller merge to mainline

[KAMEZAWA Hiroyuki]

On Wed, 30 Jul 2008 11:52:26 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu at jp.fujitsu.com> wrote:
> mem+swap controller means a shrink to memory resource controller 
> (try_to_free_mem_cgroup_pages()) should drop only file caches.
> (Because kick-out-to-swap will never changes the usage.)
> 
> right ? only global-lru can make a swap.
> maybe I can add optimization to do this. Hmm. I should see how OOM works
> under some situation.
> 
(I'm sorry that I'm not a good writer of e-mail.)

A brief summary about changes to mem controller.

 - mem+swap controller which limits the # sum of pages and swap_entries.
 - mem+swap controller just drops file caches when it reaches limit.
 - under mem+swap controller, recaliming Anon pages make no sense.
   Then,
      - LRU for Anon is not necessary.
      - LRU for tmpfs/shmem is not necessary.
      just showing account is better.
 - we should see try_to_free_mem_cgroup() again to avoid too much OOM.
   Maybe Retries=5 is too small because we never do swap under us.
   a problem like struck-into-ext3-journal can easily make file-cache reclaim
   difficult.
 - need some changes to documentation.
 - Should we have on/off switch of taking swap into account ?
   or should we implement mem+swap contoller in different name than
   "memory" controller ?
   If swap is not accounted, we need to do swap-out in memory reclaiming path,
   again.
   

Thanks,
-Kame

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