Messages in this thread | | | Subject | Re: mm/compact: why use low watermark to determine whether compact is finished instead of use high watermark? | From | Vlastimil Babka <> | Date | Fri, 22 Jul 2016 11:04:20 +0200 |
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On 07/22/2016 10:56 AM, Xishi Qiu wrote: > Hi, > > I find all the watermarks in mm/compaction.c are low_wmark_pages(), > so why not use high watermark to determine whether compact is finished?
Why would you use high watermark? Quite the opposite, I want to move towards min watermark (precisely, the one in alloc_flags which is usually min) in this series:
https://lkml.org/lkml/2016/6/24/222
especially:
https://lkml.org/lkml/2016/6/24/214
> e.g. > __alloc_pages_nodemask() > get_page_from_freelist() > this is fast path, use use low_wmark_pages() in __zone_watermark_ok() > > __alloc_pages_slowpath() > this is slow path, usually use min_wmark_pages()
Yes, and compaction should be finished when allocation can succeed, so match __alloc_pages_slowpath().
> > kswapd > balance_pgdat() > use high_wmark_pages() to determine whether zone is balanced > > Thanks, > Xishi Qiu >
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