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    SubjectRe: [RFC PATCH -mm] provide estimated available memory in /proc/meminfo
    On Tue, Nov 05, 2013 at 05:38:52PM -0500, Rik van Riel wrote:
    > Many load balancing and workload placing programs check /proc/meminfo
    > to estimate how much free memory is available. They generally do this
    > by adding up "free" and "cached", which was fine ten years ago, but
    > is pretty much guaranteed to be wrong today.
    > It is wrong because Cached includes memory that is not freeable as
    > page cache, for example shared memory segments, tmpfs, and ramfs,
    > and it does not include reclaimable slab memory, which can take up
    > a large fraction of system memory on mostly idle systems with lots
    > of files.
    > Currently, the amount of memory that is available for a new workload,
    > without pushing the system into swap, can be estimated from MemFree,
    > Active(file), Inactive(file), and SReclaimable, as well as the "low"
    > watermarks from /proc/zoneinfo.

    ramfs pages first go to (in)active lists, moves to unevictable later, so
    it's not really true already. ;)

    Kirill A. Shutemov

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