Messages in this thread | | | Date | Fri, 13 Mar 2009 18:19:47 +0900 | Subject | Re: [PATCH] NOMMU: Pages allocated to a ramfs inode's pagecache may get wrongly discarded | From | Minchan Kim <> |
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On Fri, Mar 13, 2009 at 5:15 PM, KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote: >> > > > The ramfs stuff is rather icky in that it adds the pages to the aging >> > > > list, marks them dirty, but does not provide a writeout method. >> > > > >> > > > This will make the paging code scan over them (continuously) trying to >> > > > clean them, failing that (lack of writeout method) and putting them back >> > > > on the list. >> > > > >> > > > Not requiring the pages to be added to the LRU would be a really good idea. >> > > > They are not discardable, be it in MMU or NOMMU mode, except when the inode >> > > > itself is discarded. >> > > >> > > Yep, these pages shouldn't be on the LRU at all. I guess that will >> > > require some tweaks to core filemap.c code. >> > >> > IMHO, UNEVICTABLE_LRU already does lru isolation. >> > only rest prblem is, getting rid of "depends on MMU" line in mm/Kconfig. >> > >> > Am I missing anything? >> >> Yes, the need to take something off that shouldn't be there to begin >> with. > > In past unevictable lru discussion, we discuss the same thing. > at that time, we found two reason of unevictable lru is better than > completely taking off. > > (1) page migration code depend on the page stay on lru. > (2) "taking off at reclaim time" can avoid adding lock to fastpath. > anyway, complely removing from lru need something lock. > we disliked it at that time
Can you explain this issue more detail when you are in convenience, please ?
> So, I think it is still true. > Of cource, better cool solution is always welcome :) > > > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >
-- Kinds regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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