On Wed, Sep 04, 2013 at 04:25:59PM -0700, David Rientjes wrote: > We've been getting warnings about an excessive amount of time spent > allocating pages for migration during memory compaction without > scheduling. isolate_freepages_block() already periodically checks for > contended locks or the need to schedule, but isolate_freepages() never > does. > > When a zone is massively long and no suitable targets can be found, this > iteration can be quite expensive without ever doing cond_resched(). > > Check periodically for the need to reschedule while the compaction free > scanner iterates. > > Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx> Ok, fair enough. Acked-by: Mel Gorman <mgorman@xxxxxxx> However I'm curious. Do you know why the combined use of compact_cached_free_pfn and pageblock skip bits is not enough for the scanner to quickly find a pageblock that is suitable for isolate_freepages_block()? Is the pageblock skip information getting cleared frequently by kswapd or something? -- 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>