Re: [RFC 0/6] zsmalloc support compaction

["ëìí/ìììêì/SW Platform(ì)AOTí(seungho1.park@lge.com)"]

Hi, Minchan.

Sorry, I got it. You made zsmalloc pages movable.
forget it.

Seungho.

2014-12-04 ìí 3:49ì "ëìí/ìììêì/SW Platform(ì)AOTí 
(seungho1.park@xxxxxxx)" ì(ê) ì ê:
> Hi, Minchan.
>
> I have a question.
> The problem mentioned can't be resolved with compaction?
> Is there any reason that zsmalloc pages can't be moved by compaction
> operation in direct reclaim?
>
> 2014-12-02 ìì 11:49ì Minchan Kim ì(ê) ì ê:
> > Recently, there was issue about zsmalloc fragmentation and
> > I got a report from Juno that new fork failed although there
> > are plenty of free pages in the system.
> > His investigation revealed zram is one of the culprit to make
> > heavy fragmentation so there was no more contiguous 16K page
> > for pgd to fork in the ARM.
> >
> > This patchset implement *basic* zsmalloc compaction support
> > and zram utilizes it so admin can do
> >     "echo 1 > /sys/block/zram0/compact"
> >
> > Actually, ideal is that mm migrate code is aware of zram pages and
> > migrate them out automatically without admin's manual opeartion
> > when system is out of contiguous page. Howver, we need more thinking
> > before adding more hooks to migrate.c. Even though we implement it,
> > we need manual trigger mode, too so I hope we could enhance
> > zram migration stuff based on this primitive functions in future.
> >
> > I just tested it on only x86 so need more testing on other arches.
> > Additionally, I should have a number for zsmalloc regression
> > caused by indirect layering. Unfortunately, I don't have any
> > ARM test machine on my desk. I will get it soon and test it.
> > Anyway, before further work, I'd like to hear opinion.
> >
> > Pathset is based on v3.18-rc6-mmotm-2014-11-26-15-45.
> >
> > Thanks.
> >
> > Minchan Kim (6):
> >    zsmalloc: expand size class to support sizeof(unsigned long)
> >    zsmalloc: add indrection layer to decouple handle from object
> >    zsmalloc: implement reverse mapping
> >    zsmalloc: encode alloced mark in handle object
> >    zsmalloc: support compaction
> >    zram: support compaction
> >
> >   drivers/block/zram/zram_drv.c |  24 ++
> >   drivers/block/zram/zram_drv.h |   1 +
> >   include/linux/zsmalloc.h      |   1 +
> >   mm/zsmalloc.c                 | 596 
> > +++++++++++++++++++++++++++++++++++++-----
> >   4 files changed, 552 insertions(+), 70 deletions(-)

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