• Mel Gorman's avatar
    tracing, page-allocator: add trace events for anti-fragmentation falling back to other migratetypes · e0fff1bd
    Mel Gorman authored
    Fragmentation avoidance depends on being able to use free pages from lists
    of the appropriate migrate type.  In the event this is not possible,
    __rmqueue_fallback() selects a different list and in some circumstances
    change the migratetype of the pageblock.  Simplistically, the more times
    this event occurs, the more likely that fragmentation will be a problem
    later for hugepage allocation at least but there are other considerations
    such as the order of page being split to satisfy the allocation.
    This patch adds a trace event for __rmqueue_fallback() that reports what
    page is being used for the fallback, the orders of relevant pages, the
    desired migratetype and the migratetype of the lists being used, whether
    the pageblock changed type and whether this event is important with
    respect to fragmentation avoidance or not.  This information can be used
    to help analyse fragmentation avoidance and help decide whether
    min_free_kbytes should be increased or not.
    Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
    Acked-by: default avatarRik van Riel <riel@redhat.com>
    Reviewed-by: default avatarIngo Molnar <mingo@elte.hu>
    Cc: Larry Woodman <lwoodman@redhat.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Li Ming Chun <macli@brc.ubc.ca>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
kmem.h 8.24 KB