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? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>