• Hugh Dickins's avatar
    ksm: treat unstable nid like in stable tree · b599cbdf
    Hugh Dickins authored
    An inconsistency emerged in reviewing the NUMA node changes to KSM: when
    meeting a page from the wrong NUMA node in a stable tree, we say that
    it's okay for comparisons, but not as a leaf for merging; whereas when
    meeting a page from the wrong NUMA node in an unstable tree, we bail out
    immediately.
    
    Now, it might be that a wrong NUMA node in an unstable tree is more
    likely to correlate with instablility (different content, with rbnode
    now misplaced) than page migration; but even so, we are accustomed to
    instablility in the unstable tree.
    
    Without strong evidence for which strategy is generally better, I'd
    rather be consistent with what's done in the stable tree: accept a page
    from the wrong NUMA node for comparison, but not as a leaf for merging.
    Signed-off-by: default avatarHugh Dickins <hughd@google.com>
    Cc: Mel Gorman <mgorman@suse.de>
    Cc: Petr Holasek <pholasek@redhat.com>
    Cc: Andrea Arcangeli <aarcange@redhat.com>
    Cc: Izik Eidus <izik.eidus@ravellosystems.com>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    b599cbdf
ksm.c 65.1 KB