• Johannes Weiner's avatar
    mm: workingset: update shadow limit to reflect bigger active list · b5388998
    Johannes Weiner authored
    Since commit 59dc76b0 ("mm: vmscan: reduce size of inactive file
    list") the size of the active file list is no longer limited to half of
    memory.  Increase the shadow node limit accordingly to avoid throwing
    out shadow entries that might still result in eligible refaults.
    
    The exact size of the active list now depends on the overall size of the
    page cache, but converges toward taking up most of the space:
    
    In mm/vmscan.c::inactive_list_is_low(),
    
     * total     target    max
     * memory    ratio     inactive
     * -------------------------------------
     *   10MB       1         5MB
     *  100MB       1        50MB
     *    1GB       3       250MB
     *   10GB      10       0.9GB
     *  100GB      31         3GB
     *    1TB     101        10GB
     *   10TB     320        32GB
    
    It would be possible to apply the same precise ratios when determining
    the limit for radix tree nodes containing shadow entries, but since it
    is merely an approximation of the oldest refault distances in the wild
    and the code also makes assumptions about the node population density,
    keep it simple and always target the full cache size.
    
    While at it, clarify the comment and the formula for memory footprint.
    
    Link: http://lkml.kernel.org/r/20161117214701.29000-1-hannes@cmpxchg.orgSigned-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
    Cc: Rik van Riel <riel@redhat.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    b5388998
workingset.c 18.1 KB