• Mel Gorman's avatar
    sched/numa: Favour moving tasks towards the preferred node · 3a7053b3
    Mel Gorman authored
    This patch favours moving tasks towards NUMA node that recorded a higher
    number of NUMA faults during active load balancing.  Ideally this is
    self-reinforcing as the longer the task runs on that node, the more faults
    it should incur causing task_numa_placement to keep the task running on that
    node. In reality a big weakness is that the nodes CPUs can be overloaded
    and it would be more efficient to queue tasks on an idle node and migrate
    to the new node. This would require additional smarts in the balancer so
    for now the balancer will simply prefer to place the task on the preferred
    node for a PTE scans which is controlled by the numa_balancing_settle_count
    sysctl. Once the settle_count number of scans has complete the schedule
    is free to place the task on an alternative node if the load is imbalanced.
    [srikar@linux.vnet.ibm.com: Fixed statistics]
    Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
    Reviewed-by: default avatarRik van Riel <riel@redhat.com>
    Cc: Andrea Arcangeli <aarcange@redhat.com>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
    [ Tunable and use higher faults instead of preferred. ]
    Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
    Link: http://lkml.kernel.org/r/1381141781-10992-23-git-send-email-mgorman@suse.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
kernel.txt 26.5 KB