• Tim Chen's avatar
    tmpfs: add accurate compare function to percpu_counter library · 27f5e0f6
    Tim Chen authored
    Add percpu_counter_compare that allows for a quick but accurate comparison
    of percpu_counter with a given value.
    
    A rough count is provided by the count field in percpu_counter structure,
    without accounting for the other values stored in individual cpu counters.
    
    The actual count is a sum of count and the cpu counters.  However, count
    field is never different from the actual value by a factor of
    batch*num_online_cpu.  We do not need to get actual count for comparison
    if count is different from the given value by this factor and allows for
    quick comparison without summing up all the per cpu counters.
    Signed-off-by: default avatarTim Chen <tim.c.chen@linux.intel.com>
    Cc: Hugh Dickins <hughd@google.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    27f5e0f6
percpu_counter.c 3.74 KB