Messages in this thread | | | Date | Tue, 10 Sep 2013 14:20:32 +0100 | From | Mel Gorman <> | Subject | Re: [patch] mm, compaction: periodically schedule when freeing pages |
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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@google.com>
Ok, fair enough.
Acked-by: Mel Gorman <mgorman@suse.de>
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
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