Messages in this thread | | | Date | Mon, 17 Nov 2008 09:06:07 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: [PATCH] mm: evict streaming IO cache first |
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On Mon, 17 Nov 2008, Rik van Riel wrote:
> Linus Torvalds wrote: > > > Another thing strikes me: it looks like the logic in "get_scan_ratio()" has > > a tendency to get unbalanced - if we end up deciding that we should scan a > > lot of anonymous pages, the scan numbers for anonymous pages will go up, and > > we get even _more_ eager to scan those. Of course, "rotate" events will then > > make us less likely again, but for streaming loads, you wouldn't expect to > > see those at all. > > True for streaming loads - if we scan the file list and find > mostly pages from streaming loads, we will become more eager > to scan the file list.
The "count adding as activity" might hide that, but it does seem a big iffy.
> > There seems to be another bug there wrt the "aging" - we age anon page > > events and file page events independently, which sounds like it would make > > the math totally nonsensical. We do that whole > > > > anon / (anon + file) > > That's an outdated comment. Andrew had a patch to update that > comment, but it must have gotten lost somewhere. I'll send you > a patch to update it. > > If you look at the actual calculation, you'l see that the > scan percentages are keyed off just swappiness and the > rotated/scanned ratios for each page category.
Ok, that makes sense. Yes, as ratios the math looks valid.
Linus
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