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Nick Piggin wrote: > Eric St-Laurent wrote: >> On Wed, 2007-25-07 at 15:19 +1000, Nick Piggin wrote: >> >> >>> What *I* think is supposed to happen is that newly read in pages get >>> put on the inactive list, and unless they get accessed againbefore >>> being reclaimed, they are allowed to fall off the end of the list >>> without disturbing active data too much. >>> >>> I think there is a missing piece here, that we used to ease the reclaim >>> pressure off the active list when the inactive list grows relatively >>> much larger than it (which could indicate a lot of use-once pages in >>> the system). >> >> >> Maybe a new list should be added to put newly read pages in it. If they >> are not used or used once after a certain period, they can be moved to >> the inactive list (or whatever). >> >> Newly read pages... >> >> - ... not used after this period are excessive readahead, we discard >> immediately. >> - ... used only once after this period, we discard soon. >> - ... used many/frequently are moved to active list. >> >> Surely the scan rate (do I make sense?) should be different for this >> newly-read list and the inactive list. > > A new list could be a possibility. One problem with adding lists is just > trying to work out how to balance scanning rates between them, another > problem is CPU overhead of moving pages from one to another... but don't > let me stop you if you want to jump in and try something :) > > >> I also remember your split mapped/unmapped active list patches from a >> while ago. >> >> Can someone point me to a up-to-date documentation about the Linux VM? >> The books and documents I've seen are outdated. > > If you just want to play with page reclaim algorithms, try reading over > mm/vmscan.c. If you don't know much about the Linux VM internals before, > don't worry too much about the fine details and start by getting an idea > of how pages move between the active and inactive lists. I've got a nice list of problems with the VM at http://linux-mm.org/PageoutFailureModes :) I should post my latest version of the split LRU lists code. I'm still working on SEQ replacement for the anonymous pages... > OK here is one which just changes the rate that the active and inactive > lists get scanned. Data corruption bugs should be minimal ;) I had something like that in mind for the file pages. I am a bit nervous about introducing such a change while file and anonymous pages share the same LRU, though... -- Politics is the struggle between those who want to make their country the best in the world, and those who believe it already is. Each group calls the other unpatriotic. - 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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