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편집 파일: 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, /* 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 successful to compact * suitable pages. */ COMPACT_COMPLETE, /* * direct compaction has scanned part of the zone but wasn't successful * 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 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 compaction_proactiveness_sysctl_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 compaction_defer_reset(struct zone *zone, int order, bool alloc_success); /* 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 void 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 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 void kcompactd_run(int nid) { } 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 */