Messages in this thread | | | From | KOSAKI Motohiro <> | Subject | Re: [PATCH mmotm] vmscan: handle may_swap more strictly (Re: [PATCH mmotm] vmscan: fix may_swap handling for memcg) | Date | Tue, 9 Jun 2009 17:24:10 +0900 (JST) |
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> On Tue, Jun 9, 2009 at 4:58 PM, KOSAKI > Motohiro<kosaki.motohiro@jp.fujitsu.com> wrote: > >> Hi, KOSAKI. > >> > >> As you know, this problem caused by if condition(priority) in shrink_zone. > >> Let me have a question. > >> > >> Why do we have to prevent scan value calculation when the priority is zero ? > >> As I know, before split-lru, we didn't do it. > >> > >> Is there any specific issue in case of the priority is zero ? > > > > Yes. > > > > example: > > > > get_scan_ratio() return anon:80%, file=20%. and the system have > > 10000 anon pages and 10000 file pages. > > > > shrink_zone() picked up 8000 anon pages and 2000 file pages. > > it mean 8000 file pages aren't scanned at all. > > > > Oops, it can makes OOM-killer although system have droppable file cache. > > > Hmm..Can that problem be happen in real system ? > The file ratio is big means that file lru list scanning is so big but > rotate is small. > It means file lru have few reclaimable page. > > Isn't it ? I am confusing. > Could you elaborate, please if you don't mind ?
hm, ok, my example was wrong. I intention is, if there are droppable file-back pages (althout only 1 page), OOM-killer shouldn't occuer.
many or few is unrelated.
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