Messages in this thread | | | Date | Fri, 7 Dec 2001 06:37:07 +0100 (CET) | From | Mike Galbraith <> | Subject | Re: Kernel 2.4.16 & Heavy I/O |
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On Thu, 6 Dec 2001, Alan Cox wrote:
> > Once a page is used twice, it's not a candidate for eviction > > until (most of) the use-once pages are gone. > > > > This means that if you have these 40 MB of used-twice-but-never-again > > buffer cache memory, this memory will never be evicted until other > > pages get promoted from use-once to active. > > Its worth noting btw that you can intentionally exploit this in an app > to get unfair use of memory. That makes me very dubious about the heuristic
In Rik's VM I had a problem with use-once when Bonnie was doing rewrite. It's used-twice data became too hard to get rid of at the aging volume we were doing, leading to an inactive shortage and unwanted swapping. The active list grew until ~all of ram was on the active list. I 'fixed' it here by keeping the dirty list very strictly ordered (lengthened it too) and requiring more than two accesses before promoting to active.
I have not seen this behavior in the new VM yet.
-Mike
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