On 10/07/2013 06:28 AM, Mel Gorman wrote: > 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: Mel Gorman <mgorman@xxxxxxx> Reviewed-by: Rik van Riel <riel@xxxxxxxxxx> -- All rights reversed -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>