include/linux/compaction.h - linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef _LINUX_COMPACTION_H
 #define _LINUX_COMPACTION_H

 /*
  * Determines how hard direct compaction should try to succeed.
  * Lower value means higher priority, analogically to reclaim priority.
  */
 enum compact_priority {
 	COMPACT_PRIO_SYNC_FULL,
 	MIN_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_FULL,
 	COMPACT_PRIO_SYNC_LIGHT,
 	MIN_COMPACT_COSTLY_PRIORITY = COMPACT_PRIO_SYNC_LIGHT,
 	DEF_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_LIGHT,
 	COMPACT_PRIO_ASYNC,
 	INIT_COMPACT_PRIORITY = COMPACT_PRIO_ASYNC
 };

 /* Return values for compact_zone() and try_to_compact_pages() */
 /* When adding new states, please adjust include/trace/events/compaction.h */
 enum compact_result {
 	/* For more detailed tracepoint output - internal to compaction */
 	COMPACT_NOT_SUITABLE_ZONE,
 	/*
 	 * compaction didn't start as it was not possible or direct reclaim
 	 * was more suitable
 	 */
 	COMPACT_SKIPPED,
 	/* compaction didn't start as it was deferred due to past failures */
 	COMPACT_DEFERRED,

 	/* compaction not active last round */
 	COMPACT_INACTIVE = COMPACT_DEFERRED,

 	/* For more detailed tracepoint output - internal to compaction */
 	COMPACT_NO_SUITABLE_PAGE,
 	/* compaction should continue to another pageblock */
 	COMPACT_CONTINUE,

 	/*
 	 * The full zone was compacted scanned but wasn't successfull to compact
 	 * suitable pages.
 	 */
 	COMPACT_COMPLETE,
 	/*
 	 * direct compaction has scanned part of the zone but wasn't successfull
 	 * to compact suitable pages.
 	 */
 	COMPACT_PARTIAL_SKIPPED,

 	/* compaction terminated prematurely due to lock contentions */
 	COMPACT_CONTENDED,

 	/*
 	 * direct compaction terminated after concluding that the allocation
 	 * should now succeed
 	 */
 	COMPACT_SUCCESS,
 };

 struct alloc_context; /* in mm/internal.h */

 /*
  * Number of free order-0 pages that should be available above given watermark
  * to make sure compaction has reasonable chance of not running out of free
  * pages that it needs to isolate as migration target during its work.
  */
 static inline unsigned long compact_gap(unsigned int order)
 {
 	/*
 	 * Although all the isolations for migration are temporary, compaction
 	 * free scanner may have up to 1 << order pages on its list and then
 	 * try to split an (order - 1) free page. At that point, a gap of
 	 * 1 << order might not be enough, so it's safer to require twice that
 	 * amount. Note that the number of pages on the list is also
 	 * effectively limited by COMPACT_CLUSTER_MAX, as that's the maximum
 	 * that the migrate scanner can have isolated on migrate list, and free
 	 * scanner is only invoked when the number of isolated free pages is
 	 * lower than that. But it's not worth to complicate the formula here
 	 * as a bigger gap for higher orders than strictly necessary can also
 	 * improve chances of compaction success.
 	 */
 	return 2UL << order;
 }

 #ifdef CONFIG_COMPACTION
 extern int sysctl_compact_memory;
 extern unsigned int sysctl_compaction_proactiveness;
 extern int sysctl_compaction_handler(struct ctl_table *table, int write,
 			void *buffer, size_t *length, loff_t *ppos);
 extern int sysctl_extfrag_threshold;
 extern int sysctl_compact_unevictable_allowed;

 extern unsigned int extfrag_for_order(struct zone *zone, unsigned int order);
 extern int fragmentation_index(struct zone *zone, unsigned int order);
 extern enum compact_result try_to_compact_pages(gfp_t gfp_mask,
 		unsigned int order, unsigned int alloc_flags,
 		const struct alloc_context *ac, enum compact_priority prio,
 		struct page **page);
 extern void reset_isolation_suitable(pg_data_t *pgdat);
 extern enum compact_result compaction_suitable(struct zone *zone, int order,
 		unsigned int alloc_flags, int highest_zoneidx);

 extern void defer_compaction(struct zone *zone, int order);
 extern bool compaction_deferred(struct zone *zone, int order);
 extern void compaction_defer_reset(struct zone *zone, int order,
 				bool alloc_success);
 extern bool compaction_restarting(struct zone *zone, int order);

 /* Compaction has made some progress and retrying makes sense */
 static inline bool compaction_made_progress(enum compact_result result)
 {
 	/*
 	 * Even though this might sound confusing this in fact tells us
 	 * that the compaction successfully isolated and migrated some
 	 * pageblocks.
 	 */
 	if (result == COMPACT_SUCCESS)
 		return true;

 	return false;
 }

 /* Compaction has failed and it doesn't make much sense to keep retrying. */
 static inline bool compaction_failed(enum compact_result result)
 {
 	/* All zones were scanned completely and still not result. */
 	if (result == COMPACT_COMPLETE)
 		return true;

 	return false;
 }

 /* Compaction needs reclaim to be performed first, so it can continue. */
 static inline bool compaction_needs_reclaim(enum compact_result result)
 {
 	/*
 	 * Compaction backed off due to watermark checks for order-0
 	 * so the regular reclaim has to try harder and reclaim something.
 	 */
 	if (result == COMPACT_SKIPPED)
 		return true;

 	return false;
 }

 /*
  * Compaction has backed off for some reason after doing some work or none
  * at all. It might be throttling or lock contention. Retrying might be still
  * worthwhile, but with a higher priority if allowed.
  */
 static inline bool compaction_withdrawn(enum compact_result result)
 {
 	/*
 	 * If compaction is deferred for high-order allocations, it is
 	 * because sync compaction recently failed. If this is the case
 	 * and the caller requested a THP allocation, we do not want
 	 * to heavily disrupt the system, so we fail the allocation
 	 * instead of entering direct reclaim.
 	 */
 	if (result == COMPACT_DEFERRED)
 		return true;

 	/*
 	 * If compaction in async mode encounters contention or blocks higher
 	 * priority task we back off early rather than cause stalls.
 	 */
 	if (result == COMPACT_CONTENDED)
 		return true;

 	/*
 	 * Page scanners have met but we haven't scanned full zones so this
 	 * is a back off in fact.
 	 */
 	if (result == COMPACT_PARTIAL_SKIPPED)
 		return true;

 	return false;
 }


 bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
 					int alloc_flags);

 extern int kcompactd_run(int nid);
 extern void kcompactd_stop(int nid);
 extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int highest_zoneidx);

 #else
 static inline void reset_isolation_suitable(pg_data_t *pgdat)
 {
 }

 static inline enum compact_result compaction_suitable(struct zone *zone, int order,
 					int alloc_flags, int highest_zoneidx)
 {
 	return COMPACT_SKIPPED;
 }

 static inline void defer_compaction(struct zone *zone, int order)
 {
 }

 static inline bool compaction_deferred(struct zone *zone, int order)
 {
 	return true;
 }

 static inline bool compaction_made_progress(enum compact_result result)
 {
 	return false;
 }

 static inline bool compaction_failed(enum compact_result result)
 {
 	return false;
 }

 static inline bool compaction_needs_reclaim(enum compact_result result)
 {
 	return false;
 }

 static inline bool compaction_withdrawn(enum compact_result result)
 {
 	return true;
 }

 static inline int kcompactd_run(int nid)
 {
 	return 0;
 }
 static inline void kcompactd_stop(int nid)
 {
 }

 static inline void wakeup_kcompactd(pg_data_t *pgdat,
 				int order, int highest_zoneidx)
 {
 }

 #endif /* CONFIG_COMPACTION */

 struct node;
 #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
 extern int compaction_register_node(struct node *node);
 extern void compaction_unregister_node(struct node *node);

 #else

 static inline int compaction_register_node(struct node *node)
 {
 	return 0;
 }

 static inline void compaction_unregister_node(struct node *node)
 {
 }
 #endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */

 #endif /* _LINUX_COMPACTION_H */
	/* SPDX-License-Identifier: GPL-2.0 */
	#ifndef _LINUX_COMPACTION_H
	#define _LINUX_COMPACTION_H

	/*
	* Determines how hard direct compaction should try to succeed.
	* Lower value means higher priority, analogically to reclaim priority.
	*/
	enum compact_priority {
	COMPACT_PRIO_SYNC_FULL,
	MIN_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_FULL,
	COMPACT_PRIO_SYNC_LIGHT,
	MIN_COMPACT_COSTLY_PRIORITY = COMPACT_PRIO_SYNC_LIGHT,
	DEF_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_LIGHT,
	COMPACT_PRIO_ASYNC,
	INIT_COMPACT_PRIORITY = COMPACT_PRIO_ASYNC
	};

	/* Return values for compact_zone() and try_to_compact_pages() */
	/* When adding new states, please adjust include/trace/events/compaction.h */
	enum compact_result {
	/* For more detailed tracepoint output - internal to compaction */
	COMPACT_NOT_SUITABLE_ZONE,
	/*
	* compaction didn't start as it was not possible or direct reclaim
	* was more suitable
	*/
	COMPACT_SKIPPED,
	/* compaction didn't start as it was deferred due to past failures */
	COMPACT_DEFERRED,

	/* compaction not active last round */
	COMPACT_INACTIVE = COMPACT_DEFERRED,

	/* For more detailed tracepoint output - internal to compaction */
	COMPACT_NO_SUITABLE_PAGE,
	/* compaction should continue to another pageblock */
	COMPACT_CONTINUE,

	/*
	* The full zone was compacted scanned but wasn't successfull to compact
	* suitable pages.
	*/
	COMPACT_COMPLETE,
	/*
	* direct compaction has scanned part of the zone but wasn't successfull
	* to compact suitable pages.
	*/
	COMPACT_PARTIAL_SKIPPED,

	/* compaction terminated prematurely due to lock contentions */
	COMPACT_CONTENDED,

	/*
	* direct compaction terminated after concluding that the allocation
	* should now succeed
	*/
	COMPACT_SUCCESS,
	};

	struct alloc_context; /* in mm/internal.h */

	/*
	* Number of free order-0 pages that should be available above given watermark
	* to make sure compaction has reasonable chance of not running out of free
	* pages that it needs to isolate as migration target during its work.
	*/
	static inline unsigned long compact_gap(unsigned int order)
	{
	/*
	* Although all the isolations for migration are temporary, compaction
	* free scanner may have up to 1 << order pages on its list and then
	* try to split an (order - 1) free page. At that point, a gap of
	* 1 << order might not be enough, so it's safer to require twice that
	* amount. Note that the number of pages on the list is also
	* effectively limited by COMPACT_CLUSTER_MAX, as that's the maximum
	* that the migrate scanner can have isolated on migrate list, and free
	* scanner is only invoked when the number of isolated free pages is
	* lower than that. But it's not worth to complicate the formula here
	* as a bigger gap for higher orders than strictly necessary can also
	* improve chances of compaction success.
	*/
	return 2UL << order;
	}

	#ifdef CONFIG_COMPACTION
	extern int sysctl_compact_memory;
	extern unsigned int sysctl_compaction_proactiveness;
	extern int sysctl_compaction_handler(struct ctl_table *table, int write,
	void buffer, size_t length, loff_t *ppos);
	extern int sysctl_extfrag_threshold;
	extern int sysctl_compact_unevictable_allowed;

	extern unsigned int extfrag_for_order(struct zone *zone, unsigned int order);
	extern int fragmentation_index(struct zone *zone, unsigned int order);
	extern enum compact_result try_to_compact_pages(gfp_t gfp_mask,
	unsigned int order, unsigned int alloc_flags,
	const struct alloc_context *ac, enum compact_priority prio,
	struct page **page);
	extern void reset_isolation_suitable(pg_data_t *pgdat);
	extern enum compact_result compaction_suitable(struct zone *zone, int order,
	unsigned int alloc_flags, int highest_zoneidx);

	extern void defer_compaction(struct zone *zone, int order);
	extern bool compaction_deferred(struct zone *zone, int order);
	extern void compaction_defer_reset(struct zone *zone, int order,
	bool alloc_success);
	extern bool compaction_restarting(struct zone *zone, int order);

	/* Compaction has made some progress and retrying makes sense */
	static inline bool compaction_made_progress(enum compact_result result)
	{
	/*
	* Even though this might sound confusing this in fact tells us
	* that the compaction successfully isolated and migrated some
	* pageblocks.
	*/
	if (result == COMPACT_SUCCESS)
	return true;

	return false;
	}

	/* Compaction has failed and it doesn't make much sense to keep retrying. */
	static inline bool compaction_failed(enum compact_result result)
	{
	/* All zones were scanned completely and still not result. */
	if (result == COMPACT_COMPLETE)
	return true;

	return false;
	}

	/* Compaction needs reclaim to be performed first, so it can continue. */
	static inline bool compaction_needs_reclaim(enum compact_result result)
	{
	/*
	* Compaction backed off due to watermark checks for order-0
	* so the regular reclaim has to try harder and reclaim something.
	*/
	if (result == COMPACT_SKIPPED)
	return true;

	return false;
	}

	/*
	* Compaction has backed off for some reason after doing some work or none
	* at all. It might be throttling or lock contention. Retrying might be still
	* worthwhile, but with a higher priority if allowed.
	*/
	static inline bool compaction_withdrawn(enum compact_result result)
	{
	/*
	* If compaction is deferred for high-order allocations, it is
	* because sync compaction recently failed. If this is the case
	* and the caller requested a THP allocation, we do not want
	* to heavily disrupt the system, so we fail the allocation
	* instead of entering direct reclaim.
	*/
	if (result == COMPACT_DEFERRED)
	return true;

	/*
	* If compaction in async mode encounters contention or blocks higher
	* priority task we back off early rather than cause stalls.
	*/
	if (result == COMPACT_CONTENDED)
	return true;

	/*
	* Page scanners have met but we haven't scanned full zones so this
	* is a back off in fact.
	*/
	if (result == COMPACT_PARTIAL_SKIPPED)
	return true;

	return false;
	}


	bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
	int alloc_flags);

	extern int kcompactd_run(int nid);
	extern void kcompactd_stop(int nid);
	extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int highest_zoneidx);

	#else
	static inline void reset_isolation_suitable(pg_data_t *pgdat)
	{
	}

	static inline enum compact_result compaction_suitable(struct zone *zone, int order,
	int alloc_flags, int highest_zoneidx)
	{
	return COMPACT_SKIPPED;
	}

	static inline void defer_compaction(struct zone *zone, int order)
	{
	}

	static inline bool compaction_deferred(struct zone *zone, int order)
	{
	return true;
	}

	static inline bool compaction_made_progress(enum compact_result result)
	{
	return false;
	}

	static inline bool compaction_failed(enum compact_result result)
	{
	return false;
	}

	static inline bool compaction_needs_reclaim(enum compact_result result)
	{
	return false;
	}

	static inline bool compaction_withdrawn(enum compact_result result)
	{
	return true;
	}

	static inline int kcompactd_run(int nid)
	{
	return 0;
	}
	static inline void kcompactd_stop(int nid)
	{
	}

	static inline void wakeup_kcompactd(pg_data_t *pgdat,
	int order, int highest_zoneidx)
	{
	}

	#endif /* CONFIG_COMPACTION */

	struct node;
	#if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
	extern int compaction_register_node(struct node *node);
	extern void compaction_unregister_node(struct node *node);

	#else

	static inline int compaction_register_node(struct node *node)
	{
	return 0;
	}

	static inline void compaction_unregister_node(struct node *node)
	{
	}
	#endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */

	#endif /* _LINUX_COMPACTION_H */