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ecd8b2928f
Patch series "mm: compaction: cleanups & simplifications". These compaction cleanups are split out from the huge page allocator series[1], as requested by reviewer feedback. [1] https://lore.kernel.org/linux-mm/20230418191313.268131-1-hannes@cmpxchg.org/ This patch (of 5): The compaction result helpers encode quirks that are specific to the allocator's retry logic. E.g. COMPACT_SUCCESS and COMPACT_COMPLETE actually represent failures that should be retried upon, and so on. I frequently found myself pulling up the helper implementation in order to understand and work on the retry logic. They're not quite clean abstractions; rather they split the retry logic into two locations. Remove the helpers and inline the checks. Then comment on the result interpretations directly where the decision making happens. Link: https://lkml.kernel.org/r/20230519123959.77335-1-hannes@cmpxchg.org Link: https://lkml.kernel.org/r/20230519123959.77335-2-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
147 lines
4.5 KiB
C
147 lines
4.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_COMPACTION_H
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#define _LINUX_COMPACTION_H
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/*
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* Determines how hard direct compaction should try to succeed.
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* Lower value means higher priority, analogically to reclaim priority.
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*/
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enum compact_priority {
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COMPACT_PRIO_SYNC_FULL,
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MIN_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_FULL,
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COMPACT_PRIO_SYNC_LIGHT,
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MIN_COMPACT_COSTLY_PRIORITY = COMPACT_PRIO_SYNC_LIGHT,
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DEF_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_LIGHT,
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COMPACT_PRIO_ASYNC,
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INIT_COMPACT_PRIORITY = COMPACT_PRIO_ASYNC
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};
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/* Return values for compact_zone() and try_to_compact_pages() */
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/* When adding new states, please adjust include/trace/events/compaction.h */
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enum compact_result {
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/* For more detailed tracepoint output - internal to compaction */
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COMPACT_NOT_SUITABLE_ZONE,
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/*
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* compaction didn't start as it was not possible or direct reclaim
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* was more suitable
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*/
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COMPACT_SKIPPED,
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/* compaction didn't start as it was deferred due to past failures */
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COMPACT_DEFERRED,
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/* For more detailed tracepoint output - internal to compaction */
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COMPACT_NO_SUITABLE_PAGE,
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/* compaction should continue to another pageblock */
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COMPACT_CONTINUE,
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/*
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* The full zone was compacted scanned but wasn't successful to compact
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* suitable pages.
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*/
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COMPACT_COMPLETE,
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/*
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* direct compaction has scanned part of the zone but wasn't successful
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* to compact suitable pages.
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*/
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COMPACT_PARTIAL_SKIPPED,
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/* compaction terminated prematurely due to lock contentions */
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COMPACT_CONTENDED,
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/*
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* direct compaction terminated after concluding that the allocation
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* should now succeed
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*/
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COMPACT_SUCCESS,
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};
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struct alloc_context; /* in mm/internal.h */
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/*
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* Number of free order-0 pages that should be available above given watermark
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* to make sure compaction has reasonable chance of not running out of free
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* pages that it needs to isolate as migration target during its work.
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*/
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static inline unsigned long compact_gap(unsigned int order)
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{
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/*
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* Although all the isolations for migration are temporary, compaction
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* free scanner may have up to 1 << order pages on its list and then
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* try to split an (order - 1) free page. At that point, a gap of
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* 1 << order might not be enough, so it's safer to require twice that
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* amount. Note that the number of pages on the list is also
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* effectively limited by COMPACT_CLUSTER_MAX, as that's the maximum
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* that the migrate scanner can have isolated on migrate list, and free
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* scanner is only invoked when the number of isolated free pages is
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* lower than that. But it's not worth to complicate the formula here
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* as a bigger gap for higher orders than strictly necessary can also
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* improve chances of compaction success.
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*/
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return 2UL << order;
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}
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#ifdef CONFIG_COMPACTION
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extern unsigned int extfrag_for_order(struct zone *zone, unsigned int order);
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extern int fragmentation_index(struct zone *zone, unsigned int order);
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extern enum compact_result try_to_compact_pages(gfp_t gfp_mask,
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unsigned int order, unsigned int alloc_flags,
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const struct alloc_context *ac, enum compact_priority prio,
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struct page **page);
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extern void reset_isolation_suitable(pg_data_t *pgdat);
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extern enum compact_result compaction_suitable(struct zone *zone, int order,
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unsigned int alloc_flags, int highest_zoneidx);
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extern void compaction_defer_reset(struct zone *zone, int order,
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bool alloc_success);
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bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
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int alloc_flags);
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extern void kcompactd_run(int nid);
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extern void kcompactd_stop(int nid);
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extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int highest_zoneidx);
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#else
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static inline void reset_isolation_suitable(pg_data_t *pgdat)
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{
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}
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static inline enum compact_result compaction_suitable(struct zone *zone, int order,
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int alloc_flags, int highest_zoneidx)
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{
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return COMPACT_SKIPPED;
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}
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static inline void kcompactd_run(int nid)
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{
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}
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static inline void kcompactd_stop(int nid)
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{
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}
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static inline void wakeup_kcompactd(pg_data_t *pgdat,
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int order, int highest_zoneidx)
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{
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}
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#endif /* CONFIG_COMPACTION */
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struct node;
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#if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
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extern int compaction_register_node(struct node *node);
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extern void compaction_unregister_node(struct node *node);
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#else
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static inline int compaction_register_node(struct node *node)
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{
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return 0;
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}
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static inline void compaction_unregister_node(struct node *node)
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{
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}
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#endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
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#endif /* _LINUX_COMPACTION_H */
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