mm, page_alloc: remove MIGRATE_RESERVE
MIGRATE_RESERVE preserves an old property of the buddy allocator that existed prior to fragmentation avoidance -- min_free_kbytes worth of pages tended to remain contiguous until the only alternative was to fail the allocation. At the time it was discovered that high-order atomic allocations relied on this property so MIGRATE_RESERVE was introduced. A later patch will introduce an alternative MIGRATE_HIGHATOMIC so this patch deletes MIGRATE_RESERVE and supporting code so it'll be easier to review. Note that this patch in isolation may look like a false regression if someone was bisecting high-order atomic allocation failures. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mel Gorman
Linus Torvalds
Родитель
f77cf4e4cc
Коммит
974a786e63
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@ -39,8 +39,6 @@ enum {
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MIGRATE_UNMOVABLE,
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MIGRATE_MOVABLE,
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MIGRATE_RECLAIMABLE,
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MIGRATE_PCPTYPES, /* the number of types on the pcp lists */
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MIGRATE_RESERVE = MIGRATE_PCPTYPES,
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#ifdef CONFIG_CMA
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/*
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* MIGRATE_CMA migration type is designed to mimic the way
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@ -63,6 +61,8 @@ enum {
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MIGRATE_TYPES
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};
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#define MIGRATE_PCPTYPES (MIGRATE_RECLAIMABLE+1)
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#ifdef CONFIG_CMA
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# define is_migrate_cma(migratetype) unlikely((migratetype) == MIGRATE_CMA)
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#else
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@ -429,12 +429,6 @@ struct zone {
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const char *name;
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/*
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* Number of MIGRATE_RESERVE page block. To maintain for just
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* optimization. Protected by zone->lock.
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*/
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int nr_migrate_reserve_block;
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#ifdef CONFIG_MEMORY_ISOLATION
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/*
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* Number of isolated pageblock. It is used to solve incorrect
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@ -116,7 +116,7 @@ static void set_recommended_min_free_kbytes(void)
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for_each_populated_zone(zone)
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nr_zones++;
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/* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */
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/* Ensure 2 pageblocks are free to assist fragmentation avoidance */
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recommended_min = pageblock_nr_pages * nr_zones * 2;
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/*
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148
mm/page_alloc.c
148
mm/page_alloc.c
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@ -817,7 +817,6 @@ static void free_pcppages_bulk(struct zone *zone, int count,
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if (unlikely(has_isolate_pageblock(zone)))
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mt = get_pageblock_migratetype(page);
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/* MIGRATE_MOVABLE list may include MIGRATE_RESERVEs */
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__free_one_page(page, page_to_pfn(page), zone, 0, mt);
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trace_mm_page_pcpu_drain(page, 0, mt);
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} while (--to_free && --batch_free && !list_empty(list));
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@ -1417,15 +1416,14 @@ struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
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* the free lists for the desirable migrate type are depleted
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*/
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static int fallbacks[MIGRATE_TYPES][4] = {
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[MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE, MIGRATE_RESERVE },
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[MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE, MIGRATE_RESERVE },
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[MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_RESERVE },
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[MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE, MIGRATE_TYPES },
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[MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE, MIGRATE_TYPES },
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[MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_TYPES },
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#ifdef CONFIG_CMA
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[MIGRATE_CMA] = { MIGRATE_RESERVE }, /* Never used */
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[MIGRATE_CMA] = { MIGRATE_TYPES }, /* Never used */
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#endif
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[MIGRATE_RESERVE] = { MIGRATE_RESERVE }, /* Never used */
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#ifdef CONFIG_MEMORY_ISOLATION
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[MIGRATE_ISOLATE] = { MIGRATE_RESERVE }, /* Never used */
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[MIGRATE_ISOLATE] = { MIGRATE_TYPES }, /* Never used */
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#endif
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};
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@ -1598,7 +1596,7 @@ int find_suitable_fallback(struct free_area *area, unsigned int order,
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*can_steal = false;
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for (i = 0;; i++) {
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fallback_mt = fallbacks[migratetype][i];
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if (fallback_mt == MIGRATE_RESERVE)
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if (fallback_mt == MIGRATE_TYPES)
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break;
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if (list_empty(&area->free_list[fallback_mt]))
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@ -1676,25 +1674,13 @@ static struct page *__rmqueue(struct zone *zone, unsigned int order,
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{
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struct page *page;
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retry_reserve:
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page = __rmqueue_smallest(zone, order, migratetype);
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if (unlikely(!page) && migratetype != MIGRATE_RESERVE) {
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if (unlikely(!page)) {
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if (migratetype == MIGRATE_MOVABLE)
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page = __rmqueue_cma_fallback(zone, order);
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if (!page)
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page = __rmqueue_fallback(zone, order, migratetype);
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/*
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* Use MIGRATE_RESERVE rather than fail an allocation. goto
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* is used because __rmqueue_smallest is an inline function
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* and we want just one call site
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*/
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if (!page) {
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migratetype = MIGRATE_RESERVE;
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goto retry_reserve;
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}
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}
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trace_mm_page_alloc_zone_locked(page, order, migratetype);
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@ -3492,7 +3478,6 @@ static void show_migration_types(unsigned char type)
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[MIGRATE_UNMOVABLE] = 'U',
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[MIGRATE_RECLAIMABLE] = 'E',
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[MIGRATE_MOVABLE] = 'M',
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[MIGRATE_RESERVE] = 'R',
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#ifdef CONFIG_CMA
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[MIGRATE_CMA] = 'C',
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#endif
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@ -4302,120 +4287,6 @@ static inline unsigned long wait_table_bits(unsigned long size)
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return ffz(~size);
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}
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/*
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* Check if a pageblock contains reserved pages
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*/
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static int pageblock_is_reserved(unsigned long start_pfn, unsigned long end_pfn)
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{
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unsigned long pfn;
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for (pfn = start_pfn; pfn < end_pfn; pfn++) {
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if (!pfn_valid_within(pfn) || PageReserved(pfn_to_page(pfn)))
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return 1;
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}
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return 0;
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}
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/*
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* Mark a number of pageblocks as MIGRATE_RESERVE. The number
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* of blocks reserved is based on min_wmark_pages(zone). The memory within
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* the reserve will tend to store contiguous free pages. Setting min_free_kbytes
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* higher will lead to a bigger reserve which will get freed as contiguous
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* blocks as reclaim kicks in
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*/
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static void setup_zone_migrate_reserve(struct zone *zone)
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{
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unsigned long start_pfn, pfn, end_pfn, block_end_pfn;
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struct page *page;
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unsigned long block_migratetype;
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int reserve;
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int old_reserve;
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/*
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* Get the start pfn, end pfn and the number of blocks to reserve
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* We have to be careful to be aligned to pageblock_nr_pages to
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* make sure that we always check pfn_valid for the first page in
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* the block.
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*/
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start_pfn = zone->zone_start_pfn;
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end_pfn = zone_end_pfn(zone);
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start_pfn = roundup(start_pfn, pageblock_nr_pages);
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reserve = roundup(min_wmark_pages(zone), pageblock_nr_pages) >>
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pageblock_order;
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/*
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* Reserve blocks are generally in place to help high-order atomic
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* allocations that are short-lived. A min_free_kbytes value that
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* would result in more than 2 reserve blocks for atomic allocations
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* is assumed to be in place to help anti-fragmentation for the
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* future allocation of hugepages at runtime.
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*/
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reserve = min(2, reserve);
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old_reserve = zone->nr_migrate_reserve_block;
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/* When memory hot-add, we almost always need to do nothing */
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if (reserve == old_reserve)
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return;
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zone->nr_migrate_reserve_block = reserve;
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for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
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if (!early_page_nid_uninitialised(pfn, zone_to_nid(zone)))
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return;
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if (!pfn_valid(pfn))
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continue;
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page = pfn_to_page(pfn);
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/* Watch out for overlapping nodes */
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if (page_to_nid(page) != zone_to_nid(zone))
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continue;
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block_migratetype = get_pageblock_migratetype(page);
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/* Only test what is necessary when the reserves are not met */
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if (reserve > 0) {
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/*
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* Blocks with reserved pages will never free, skip
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* them.
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*/
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block_end_pfn = min(pfn + pageblock_nr_pages, end_pfn);
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if (pageblock_is_reserved(pfn, block_end_pfn))
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continue;
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/* If this block is reserved, account for it */
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if (block_migratetype == MIGRATE_RESERVE) {
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reserve--;
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continue;
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}
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/* Suitable for reserving if this block is movable */
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if (block_migratetype == MIGRATE_MOVABLE) {
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set_pageblock_migratetype(page,
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MIGRATE_RESERVE);
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move_freepages_block(zone, page,
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MIGRATE_RESERVE);
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reserve--;
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continue;
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}
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} else if (!old_reserve) {
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/*
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* At boot time we don't need to scan the whole zone
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* for turning off MIGRATE_RESERVE.
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*/
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break;
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}
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/*
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* If the reserve is met and this is a previous reserved block,
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* take it back
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*/
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if (block_migratetype == MIGRATE_RESERVE) {
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set_pageblock_migratetype(page, MIGRATE_MOVABLE);
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move_freepages_block(zone, page, MIGRATE_MOVABLE);
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}
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}
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}
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/*
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* Initially all pages are reserved - free ones are freed
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* up by free_all_bootmem() once the early boot process is
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@ -4455,9 +4326,7 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
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* movable at startup. This will force kernel allocations
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* to reserve their blocks rather than leaking throughout
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* the address space during boot when many long-lived
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* kernel allocations are made. Later some blocks near
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* the start are marked MIGRATE_RESERVE by
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* setup_zone_migrate_reserve()
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* kernel allocations are made.
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*
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* bitmap is created for zone's valid pfn range. but memmap
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* can be created for invalid pages (for alignment)
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@ -6018,7 +5887,6 @@ static void __setup_per_zone_wmarks(void)
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high_wmark_pages(zone) - low_wmark_pages(zone) -
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atomic_long_read(&zone->vm_stat[NR_ALLOC_BATCH]));
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setup_zone_migrate_reserve(zone);
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spin_unlock_irqrestore(&zone->lock, flags);
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}
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@ -923,7 +923,6 @@ static char * const migratetype_names[MIGRATE_TYPES] = {
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"Unmovable",
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"Reclaimable",
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"Movable",
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"Reserve",
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#ifdef CONFIG_CMA
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"CMA",
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#endif
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