lkml.org 
[lkml]   [2010]   [Nov]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH 1/3] mm: kswapd: Stop high-order balancing when any suitable zone is balanced
    From
    Date
    On Wed, 2010-12-01 at 01:15 +0800, Mel Gorman wrote:
    > When the allocator enters its slow path, kswapd is woken up to balance the
    > node. It continues working until all zones within the node are balanced. For
    > order-0 allocations, this makes perfect sense but for higher orders it can
    > have unintended side-effects. If the zone sizes are imbalanced, kswapd
    > may reclaim heavily on a smaller zone discarding an excessive number of
    > pages. The user-visible behaviour is that kswapd is awake and reclaiming
    > even though plenty of pages are free from a suitable zone.
    >
    > This patch alters the "balance" logic to stop kswapd if any suitable zone
    > becomes balanced to reduce the number of pages it reclaims from other zones.
    from my understanding, the patch will break reclaim high zone if a low
    zone meets the high order allocation, even the high zone doesn't meet
    the high order allocation. This, for example, will make a high order
    allocation from a high zone fallback to low zone and quickly exhaust low
    zone, for example DMA. This will break some drivers.



    \
     
     \ /
      Last update: 2010-12-01 03:17    [W:0.022 / U:0.912 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site