Messages in this thread | | | Date | Wed, 21 Mar 2007 08:03:02 -0400 | From | Rik van Riel <> | Subject | Re: [RFC][PATCH] split file and anonymous page queues #3 |
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Rik van Riel wrote: > Nikita Danilov wrote: > >> Probably I am missing something, but I don't see how that can help. For >> example, suppose (for simplicity) that we have swappiness of 100%, and >> that fraction of referenced anon pages gets slightly less than of file >> pages. get_scan_ratio() increases anon_percent, and shrink_zone() starts >> scanning anon queue more aggressively. As a result, pages spend less >> time there, and have less chance of ever being accessed, reducing >> fraction of referenced anon pages further, and triggering further >> increase in the amount of scanning, etc. Doesn't this introduce positive >> feed-back loop? > > It's a possibility, but I don't think it will be much of an > issue in practice. > > If it is, we can always use refaults as a correcting > mechanism - which would have the added benefit of being > able to do streaming IO without putting any pressure on > the active list, essentially clock-pro replacement with > just some tweaks to shrink_list()...
As an aside, due to the use-once algorithm file pages are at a natural disadvantage already. I believe it would be really hard to construct a workload where anon pages suffer the positive feedback loop you describe...
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