On Sat, Dec 10, 2016 at 12:26:58PM -0500, Johannes Weiner wrote: > When FADV_DONTNEED cannot drop all pages in the range, it observes > that some pages might still be on per-cpu LRU caches after recent > instantiation and so initiates remote calls to all CPUs to flush their > local caches. However, in most cases, the fadvise happens from the > same context that instantiated the pages, and any pre-LRU pages in the > specified range are most likely sitting on the local CPU's LRU cache, > and so in many cases this results in unnecessary remote calls, which, > in a loaded system, can hold up the fadvise() call significantly. > > Try to avoid the remote call by flushing the local LRU cache before > even attempting to invalidate anything. It's a cheap operation, and > the local LRU cache is the most likely to hold any pre-LRU pages in > the specified fadvise range. > > Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx> Acked-by: Mel Gorman <mgorman@xxxxxxx> -- Mel Gorman SUSE Labs -- 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>