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 오전 11:49에 Minchan Kim 이(가) 쓴 글:
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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