forked from luck/tmp_suning_uos_patched
5bbe3547aa
Currently, pages which are marked as unevictable are protected from compaction, but not from other types of migration. The POSIX real time extension explicitly states that mlock() will prevent a major page fault, but the spirit of this is that mlock() should give a process the ability to control sources of latency, including minor page faults. However, the mlock manpage only explicitly says that a locked page will not be written to swap and this can cause some confusion. The compaction code today does not give a developer who wants to avoid swap but wants to have large contiguous areas available any method to achieve this state. This patch introduces a sysctl for controlling compaction behavior with respect to the unevictable lru. Users who demand no page faults after a page is present can set compact_unevictable_allowed to 0 and users who need the large contiguous areas can enable compaction on locked memory by leaving the default value of 1. To illustrate this problem I wrote a quick test program that mmaps a large number of 1MB files filled with random data. These maps are created locked and read only. Then every other mmap is unmapped and I attempt to allocate huge pages to the static huge page pool. When the compact_unevictable_allowed sysctl is 0, I cannot allocate hugepages after fragmenting memory. When the value is set to 1, allocations succeed. Signed-off-by: Eric B Munson <emunson@akamai.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Christoph Lameter <cl@linux.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Mel Gorman <mgorman@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
105 lines
3.4 KiB
C
105 lines
3.4 KiB
C
#ifndef _LINUX_COMPACTION_H
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#define _LINUX_COMPACTION_H
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/* Return values for compact_zone() and try_to_compact_pages() */
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/* compaction didn't start as it was deferred due to past failures */
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#define COMPACT_DEFERRED 0
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/* compaction didn't start as it was not possible or direct reclaim was more suitable */
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#define COMPACT_SKIPPED 1
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/* compaction should continue to another pageblock */
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#define COMPACT_CONTINUE 2
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/* direct compaction partially compacted a zone and there are suitable pages */
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#define COMPACT_PARTIAL 3
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/* The full zone was compacted */
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#define COMPACT_COMPLETE 4
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/* For more detailed tracepoint output */
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#define COMPACT_NO_SUITABLE_PAGE 5
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#define COMPACT_NOT_SUITABLE_ZONE 6
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/* When adding new state, please change compaction_status_string, too */
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/* Used to signal whether compaction detected need_sched() or lock contention */
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/* No contention detected */
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#define COMPACT_CONTENDED_NONE 0
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/* Either need_sched() was true or fatal signal pending */
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#define COMPACT_CONTENDED_SCHED 1
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/* Zone lock or lru_lock was contended in async compaction */
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#define COMPACT_CONTENDED_LOCK 2
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struct alloc_context; /* in mm/internal.h */
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#ifdef CONFIG_COMPACTION
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extern int sysctl_compact_memory;
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extern int sysctl_compaction_handler(struct ctl_table *table, int write,
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void __user *buffer, size_t *length, loff_t *ppos);
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extern int sysctl_extfrag_threshold;
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extern int sysctl_extfrag_handler(struct ctl_table *table, int write,
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void __user *buffer, size_t *length, loff_t *ppos);
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extern int sysctl_compact_unevictable_allowed;
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extern int fragmentation_index(struct zone *zone, unsigned int order);
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extern unsigned long try_to_compact_pages(gfp_t gfp_mask, unsigned int order,
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int alloc_flags, const struct alloc_context *ac,
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enum migrate_mode mode, int *contended);
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extern void compact_pgdat(pg_data_t *pgdat, int order);
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extern void reset_isolation_suitable(pg_data_t *pgdat);
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extern unsigned long compaction_suitable(struct zone *zone, int order,
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int alloc_flags, int classzone_idx);
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extern void defer_compaction(struct zone *zone, int order);
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extern bool compaction_deferred(struct zone *zone, int order);
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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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extern bool compaction_restarting(struct zone *zone, int order);
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#else
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static inline unsigned long try_to_compact_pages(gfp_t gfp_mask,
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unsigned int order, int alloc_flags,
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const struct alloc_context *ac,
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enum migrate_mode mode, int *contended)
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{
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return COMPACT_CONTINUE;
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}
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static inline void compact_pgdat(pg_data_t *pgdat, int order)
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{
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}
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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 unsigned long compaction_suitable(struct zone *zone, int order,
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int alloc_flags, int classzone_idx)
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{
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return COMPACT_SKIPPED;
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}
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static inline void defer_compaction(struct zone *zone, int order)
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{
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}
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static inline bool compaction_deferred(struct zone *zone, int order)
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{
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return true;
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}
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#endif /* CONFIG_COMPACTION */
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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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