From: Mel Gorman Date: Mon, 7 Oct 2013 10:28:59 +0000 (+0100) Subject: sched/numa: Update NUMA hinting faults once per scan X-Git-Tag: omap-for-v3.13/fixes-for-merge-window-take2~40^2~69 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=745d61476ddb737aad3495fa6d9a8f8c2ee59f86;p=pandora-kernel.git sched/numa: Update NUMA hinting faults once per scan 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 Reviewed-by: Rik van Riel Cc: Andrea Arcangeli Cc: Johannes Weiner Cc: Srikar Dronamraju Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1381141781-10992-22-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar --- Reading git-diff-tree failed