Re: kswapd skips compaction if reclaim order drops to zero?

From: Mel Gorman
Date: Thu Aug 15 2013 - 06:47:36 EST

On Thu, Aug 15, 2013 at 06:02:53PM +0800, Hillf Danton wrote:
> If the allocation order is not high, direct compaction does nothing.
> Can we skip compaction here if order drops to zero?

If the allocation order is not high then

pgdat_needs_compaction == (order > 0) == false == no calling compact_pdatt

In the case where order is reset to 0 due to fragmentation then it does
call compact_pgdat but it does no work due to the cc->order check in

Mel Gorman
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