Messages in this thread | | | Date | Thu, 11 Jun 2009 20:19:45 +0900 (JST) | Subject | Re: [PATCH 2/3] check unevictable flag in lumy reclaim v2 | From | "KAMEZAWA Hiroyuki" <> |
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Minchan Kim さん wrote: > On Thu, Jun 11, 2009 at 5:38 PM, KAMEZAWA > Hiroyuki<kamezawa.hiroyu@jp.fujitsu.com> wrote: >> How about this ? >> >> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> >> >> Lumpy reclaim check pages from their pfn. Then, it can find unevictable >> pages >> in its loop. >> Abort lumpy reclaim when we find Unevictable page, we never get a lump >> of pages for requested order. >> >> Changelog: v1->v2 >> ?- rewrote commet. >> >> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> >> --- >> ?mm/vmscan.c | ? ?9 +++++++++ >> ?1 file changed, 9 insertions(+) >> >> Index: lumpy-reclaim-trial/mm/vmscan.c >> =================================================================== >> --- lumpy-reclaim-trial.orig/mm/vmscan.c >> +++ lumpy-reclaim-trial/mm/vmscan.c >> @@ -936,6 +936,15 @@ static unsigned long isolate_lru_pages(u >> ? ? ? ? ? ? ? ? ? ? ? ?/* Check that we have not crossed a zone >> boundary. */ >> ? ? ? ? ? ? ? ? ? ? ? ?if (unlikely(page_zone_id(cursor_page) != >> zone_id)) >> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?continue; >> + ? ? ? ? ? ? ? ? ? ? ? /* >> + ? ? ? ? ? ? ? ? ? ? ? ?* We tries to free all pages in this range to >> create >> + ? ? ? ? ? ? ? ? ? ? ? ?* a free large page. Then, if the range >> includes a page >> + ? ? ? ? ? ? ? ? ? ? ? ?* never be reclaimed, we have no reason to do >> more. >> + ? ? ? ? ? ? ? ? ? ? ? ?* PageUnevictable page is not a page which can >> be >> + ? ? ? ? ? ? ? ? ? ? ? ?* easily freed. Abort this scan now. >> + ? ? ? ? ? ? ? ? ? ? ? ?*/ >> + ? ? ? ? ? ? ? ? ? ? ? if (unlikely(PageUnevictable(cursor_page))) >> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? break; > > __isolate_lru_pages already checked PageUnevictable to return error. > I want to remove repeated check although it is trivial. > > By your patch, It seems to remove PageUnevictable check in > __isolate_lru_pages. > yes.
> But I know that. If we remove PageUnevictable check in > __isolate_lru_pages, it can't go into BUG in non-lumpy case. ( I > mentioned following as code) > In non-lumpy case, we'll never see Unevictable, maybe.
> case -EBUSY: > /* else it is being freed elsewhere */ > list_move(&page->lru, src); > continue; > > default: > BUG(); > } > > > It means we can remove BUG in non-lumpy case and then add BUG into > __isolate_lru_pages directly. > > If we can do it, we can remove unnecessary PageUnevictable check in > __isolate_lru_page. > Hmm, but Unevicable check had tons of troubles at its implementation and I don't want to do it at once.
> I am not sure this is right in case of memcg. > I think we don't see Unevictable in memcg's path if my memcg-lru code works as designed.
I'll postpone this patch for a while until my brain works well.
Thanks, -Kame
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