Messages in this thread | | | Date | Wed, 25 Jul 2007 11:28:09 -0400 | From | Rik van Riel <> | Subject | Re: [PATCH 0/3] readahead drop behind and size adjustment |
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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). > > Andrew got rid of that logic for some reason which I don't know, but I > can't see that use-once would be terribly effective today (so your > results don't surprise me too much).
I suspect that reason is that use-once works great for page cache pages, but anonymous pages share the same LRUs and need a more balanced aging approach.
The result: an LRU list that works ok for both types of pages most of the time, but falls over in some workloads.
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