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    SubjectRe: [RFC 0/3] Recursive reclaim (on __PF_MEMALLOC)
    On Tue, 14 Aug 2007, Peter Zijlstra wrote:

    > > Ok but that could be addressed by making sure that a certain portion of
    > > memory is reserved for clean file backed pages.
    > Which gets us back to the initial problem of sizing this portion and
    > ensuring it is big enough to service the need.

    Clean file backed pages dominate memory on most boxes. They can be
    calculated by NR_FILE_PAGES - NR_FILE_DIRTY

    On my 2G system that is

    Cached: 1731480 kB
    Dirty: 424 kB

    So for most load the patch as is will fix your issues. The problem arises
    if you have extreme loads that are making the majority of pages anonymous.

    We could change min_free_kbytes to specify the number of free + clean
    pages required (if we can do atomic reclaim then we do not need it
    anymore). Then we can specify a large portion of memory for
    min_free_kbytes. 20%? That would give you 400M on my box which would
    certainly suffice.

    If the amount of clean file backed pages falls below that limit then do
    the usual reclaim. If we write anonymous pages out to swap then they
    can also become clean and reclaimable.

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      Last update: 2007-08-14 21:43    [W:0.019 / U:9.288 seconds]
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