• M
    sched/numa: Update NUMA hinting faults once per scan · 745d6147
    Mel Gorman 提交于
    NUMA hinting fault counts and placement decisions are both recorded in the
    same array which distorts the samples in an unpredictable fashion. The values
    linearly accumulate during the scan and then decay creating a sawtooth-like
    pattern in the per-node counts. It also means that placement decisions are
    time sensitive. At best it means that it is very difficult to state that
    the buffer holds a decaying average of past faulting behaviour. At worst,
    it can confuse the load balancer if it sees one node with an artifically high
    count due to very recent faulting activity and may create a bouncing effect.
    
    This patch adds a second array. numa_faults stores the historical data
    which is used for placement decisions. numa_faults_buffer holds the
    fault activity during the current scan window. When the scan completes,
    numa_faults decays and the values from numa_faults_buffer are copied
    across.
    Signed-off-by: NMel Gorman <mgorman@suse.de>
    Reviewed-by: NRik 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>
    Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
    Link: http://lkml.kernel.org/r/1381141781-10992-22-git-send-email-mgorman@suse.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
    745d6147
sched.h 77.5 KB