61  * Number of free order-0 pages that should be available above given watermark
65 static inline unsigned long compact_gap(unsigned int order)  in compact_gap()  argument
69 	 * free scanner may have up to 1 << order pages on its list and then  in compact_gap()
70 	 * try to split an (order - 1) free page. At that point, a gap of  in compact_gap()
71 	 * 1 << order might not be enough, so it's safer to require twice that  in compact_gap()
80 	return 2UL << order;  in compact_gap()
85 extern unsigned int extfrag_for_order(struct zone *zone, unsigned int order);
86 extern int fragmentation_index(struct zone *zone, unsigned int order);
88 		unsigned int order, unsigned int alloc_flags,
92 extern bool compaction_suitable(struct zone *zone, int order,
95 extern void compaction_defer_reset(struct zone *zone, int order,
98 bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
103 extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int highest_zoneidx);
110 static inline bool compaction_suitable(struct zone *zone, int order,  in compaction_suitable()  argument
124 				int order, int highest_zoneidx)  in wakeup_kcompactd()  argument