| Date | Tue, 23 Mar 2010 13:31:43 -0500 (CDT) | From | Christoph Lameter <> | Subject | Re: [PATCH 11/11] Do not compact within a preferred zone after a compaction failure |
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On Tue, 23 Mar 2010, Mel Gorman wrote:
> The fragmentation index may indicate that a failure it due to external
s/it/is/
> fragmentation, a compaction run complete and an allocation failure still
???
> fail. There are two obvious reasons as to why > > o Page migration cannot move all pages so fragmentation remains > o A suitable page may exist but watermarks are not met > > In the event of compaction and allocation failure, this patch prevents > compaction happening for a short interval. It's only recorded on the
compaction is "recorded"? deferred?
> preferred zone but that should be enough coverage. This could have been > implemented similar to the zonelist_cache but the increased size of the > zonelist did not appear to be justified.
> @@ -1787,6 +1787,9 @@ __alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order, > */ > count_vm_event(COMPACTFAIL); > > + /* On failure, avoid compaction for a short time. */ > + defer_compaction(preferred_zone, jiffies + HZ/50); > +
20ms? How was that interval determined?
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