On Thu, 2016-02-25 at 17:12 +0000, Mel Gorman wrote: > THP gives impressive gains in some cases but only if they are quickly > available. We're not going to reach the point where they are > completely > free so lets take the costs out of the fast paths finally and defer > the > cost to kswapd, kcompactd and khugepaged where it belongs. > > Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> I agree with your conclusions, but with the caveat that if we do not try to defragment memory for THP at fault time, mlocked programs might not have any opportunity at all to get transparent huge pages. I wonder if we should consider mlock one of the slow paths where we should try to actually take the time to create THPs. Also, we might consider doing THP collapse from the NUMA page migration opportunistically, if there is a free 2MB page available on the destination host. Having said all that ... Acked-by: Rik van Riel <riel@xxxxxxxxxx> -- All rights reversed
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