When MIGRATE_UNMOVABLE pages are freed from MIGRATE_UNMOVABLE type pageblock (and some MIGRATE_MOVABLE pages are left in it) waiting until an allocation takes ownership of the block may take too long. The type of the pageblock remains unchanged so the pageblock cannot be used as a migration target during compaction. Fix it by: * Adding enum compact_mode (COMPACT_ASYNC_[MOVABLE,UNMOVABLE], and COMPACT_SYNC) and then converting sync field in struct compact_control to use it. * Adding nr_pageblocks_skipped field to struct compact_control and tracking how many destination pageblocks were of MIGRATE_UNMOVABLE type. If COMPACT_ASYNC_MOVABLE mode compaction ran fully in try_to_compact_pages() (COMPACT_COMPLETE) it implies that there is not a suitable page for allocation. In this case then check how if there were enough MIGRATE_UNMOVABLE pageblocks to try a second pass in COMPACT_ASYNC_UNMOVABLE mode. * Scanning the MIGRATE_UNMOVABLE pageblocks (during COMPACT_SYNC and COMPACT_ASYNC_UNMOVABLE compaction modes) and building a count based on finding PageBuddy pages, page_count(page) == 0 or PageLRU pages. If all pages within the MIGRATE_UNMOVABLE pageblock are in one of those three sets change the whole pageblock type to MIGRATE_MOVABLE. My particular test case (on a ARM EXYNOS4 device with 512 MiB, which means 131072 standard 4KiB pages in 'Normal' zone) is to: - allocate 120000 pages for kernel's usage - free every second page (60000 pages) of memory just allocated - allocate and use 60000 pages from user space - free remaining 60000 pages of kernel memory (now we have fragmented memory occupied mostly by user space pages) - try to allocate 100 order-9 (2048 KiB) pages for kernel's usage The results: - with compaction disabled I get 11 successful allocations - with compaction enabled - 14 successful allocations - with this patch I'm able to get all 100 successful allocations NOTE: If we can make kswapd aware of order-0 request during compaction, we can enhance kswapd with changing mode to COMPACT_ASYNC_FULL (COMPACT_ASYNC_MOVABLE + COMPACT_ASYNC_UNMOVABLE). Please see the following thread: http://marc.info/?l=linux-mm&m=133552069417068&w=2 [minchan@kernel.org: minor cleanups] Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1000 lines
26 KiB
C
1000 lines
26 KiB
C
/*
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* linux/mm/compaction.c
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*
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* Memory compaction for the reduction of external fragmentation. Note that
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* this heavily depends upon page migration to do all the real heavy
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* lifting
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*
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* Copyright IBM Corp. 2007-2010 Mel Gorman <mel@csn.ul.ie>
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*/
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#include <linux/swap.h>
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#include <linux/migrate.h>
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#include <linux/compaction.h>
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#include <linux/mm_inline.h>
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#include <linux/backing-dev.h>
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#include <linux/sysctl.h>
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#include <linux/sysfs.h>
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#include "internal.h"
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#if defined CONFIG_COMPACTION || defined CONFIG_CMA
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#define CREATE_TRACE_POINTS
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#include <trace/events/compaction.h>
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static unsigned long release_freepages(struct list_head *freelist)
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{
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struct page *page, *next;
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unsigned long count = 0;
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list_for_each_entry_safe(page, next, freelist, lru) {
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list_del(&page->lru);
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__free_page(page);
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count++;
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}
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return count;
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}
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static void map_pages(struct list_head *list)
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{
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struct page *page;
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list_for_each_entry(page, list, lru) {
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arch_alloc_page(page, 0);
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kernel_map_pages(page, 1, 1);
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}
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}
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static inline bool migrate_async_suitable(int migratetype)
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{
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return is_migrate_cma(migratetype) || migratetype == MIGRATE_MOVABLE;
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}
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/*
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* Isolate free pages onto a private freelist. Caller must hold zone->lock.
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* If @strict is true, will abort returning 0 on any invalid PFNs or non-free
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* pages inside of the pageblock (even though it may still end up isolating
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* some pages).
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*/
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static unsigned long isolate_freepages_block(unsigned long blockpfn,
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unsigned long end_pfn,
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struct list_head *freelist,
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bool strict)
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{
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int nr_scanned = 0, total_isolated = 0;
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struct page *cursor;
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cursor = pfn_to_page(blockpfn);
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/* Isolate free pages. This assumes the block is valid */
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for (; blockpfn < end_pfn; blockpfn++, cursor++) {
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int isolated, i;
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struct page *page = cursor;
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if (!pfn_valid_within(blockpfn)) {
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if (strict)
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return 0;
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continue;
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}
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nr_scanned++;
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if (!PageBuddy(page)) {
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if (strict)
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return 0;
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continue;
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}
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/* Found a free page, break it into order-0 pages */
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isolated = split_free_page(page);
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if (!isolated && strict)
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return 0;
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total_isolated += isolated;
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for (i = 0; i < isolated; i++) {
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list_add(&page->lru, freelist);
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page++;
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}
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/* If a page was split, advance to the end of it */
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if (isolated) {
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blockpfn += isolated - 1;
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cursor += isolated - 1;
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}
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}
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trace_mm_compaction_isolate_freepages(nr_scanned, total_isolated);
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return total_isolated;
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}
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/**
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* isolate_freepages_range() - isolate free pages.
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* @start_pfn: The first PFN to start isolating.
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* @end_pfn: The one-past-last PFN.
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*
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* Non-free pages, invalid PFNs, or zone boundaries within the
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* [start_pfn, end_pfn) range are considered errors, cause function to
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* undo its actions and return zero.
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*
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* Otherwise, function returns one-past-the-last PFN of isolated page
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* (which may be greater then end_pfn if end fell in a middle of
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* a free page).
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*/
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unsigned long
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isolate_freepages_range(unsigned long start_pfn, unsigned long end_pfn)
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{
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unsigned long isolated, pfn, block_end_pfn, flags;
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struct zone *zone = NULL;
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LIST_HEAD(freelist);
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if (pfn_valid(start_pfn))
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zone = page_zone(pfn_to_page(start_pfn));
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for (pfn = start_pfn; pfn < end_pfn; pfn += isolated) {
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if (!pfn_valid(pfn) || zone != page_zone(pfn_to_page(pfn)))
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break;
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/*
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* On subsequent iterations ALIGN() is actually not needed,
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* but we keep it that we not to complicate the code.
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*/
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block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
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block_end_pfn = min(block_end_pfn, end_pfn);
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spin_lock_irqsave(&zone->lock, flags);
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isolated = isolate_freepages_block(pfn, block_end_pfn,
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&freelist, true);
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spin_unlock_irqrestore(&zone->lock, flags);
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/*
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* In strict mode, isolate_freepages_block() returns 0 if
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* there are any holes in the block (ie. invalid PFNs or
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* non-free pages).
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*/
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if (!isolated)
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break;
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/*
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* If we managed to isolate pages, it is always (1 << n) *
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* pageblock_nr_pages for some non-negative n. (Max order
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* page may span two pageblocks).
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*/
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}
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/* split_free_page does not map the pages */
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map_pages(&freelist);
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if (pfn < end_pfn) {
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/* Loop terminated early, cleanup. */
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release_freepages(&freelist);
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return 0;
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}
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/* We don't use freelists for anything. */
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return pfn;
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}
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/* Update the number of anon and file isolated pages in the zone */
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static void acct_isolated(struct zone *zone, struct compact_control *cc)
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{
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struct page *page;
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unsigned int count[2] = { 0, };
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list_for_each_entry(page, &cc->migratepages, lru)
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count[!!page_is_file_cache(page)]++;
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__mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]);
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__mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]);
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}
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/* Similar to reclaim, but different enough that they don't share logic */
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static bool too_many_isolated(struct zone *zone)
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{
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unsigned long active, inactive, isolated;
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inactive = zone_page_state(zone, NR_INACTIVE_FILE) +
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zone_page_state(zone, NR_INACTIVE_ANON);
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active = zone_page_state(zone, NR_ACTIVE_FILE) +
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zone_page_state(zone, NR_ACTIVE_ANON);
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isolated = zone_page_state(zone, NR_ISOLATED_FILE) +
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zone_page_state(zone, NR_ISOLATED_ANON);
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return isolated > (inactive + active) / 2;
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}
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/**
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* isolate_migratepages_range() - isolate all migrate-able pages in range.
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* @zone: Zone pages are in.
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* @cc: Compaction control structure.
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* @low_pfn: The first PFN of the range.
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* @end_pfn: The one-past-the-last PFN of the range.
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*
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* Isolate all pages that can be migrated from the range specified by
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* [low_pfn, end_pfn). Returns zero if there is a fatal signal
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* pending), otherwise PFN of the first page that was not scanned
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* (which may be both less, equal to or more then end_pfn).
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*
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* Assumes that cc->migratepages is empty and cc->nr_migratepages is
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* zero.
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*
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* Apart from cc->migratepages and cc->nr_migratetypes this function
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* does not modify any cc's fields, in particular it does not modify
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* (or read for that matter) cc->migrate_pfn.
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*/
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unsigned long
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isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
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unsigned long low_pfn, unsigned long end_pfn)
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{
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unsigned long last_pageblock_nr = 0, pageblock_nr;
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unsigned long nr_scanned = 0, nr_isolated = 0;
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struct list_head *migratelist = &cc->migratepages;
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isolate_mode_t mode = ISOLATE_ACTIVE|ISOLATE_INACTIVE;
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/*
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* Ensure that there are not too many pages isolated from the LRU
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* list by either parallel reclaimers or compaction. If there are,
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* delay for some time until fewer pages are isolated
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*/
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while (unlikely(too_many_isolated(zone))) {
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/* async migration should just abort */
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if (cc->mode != COMPACT_SYNC)
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return 0;
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congestion_wait(BLK_RW_ASYNC, HZ/10);
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if (fatal_signal_pending(current))
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return 0;
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}
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/* Time to isolate some pages for migration */
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cond_resched();
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spin_lock_irq(&zone->lru_lock);
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for (; low_pfn < end_pfn; low_pfn++) {
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struct page *page;
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bool locked = true;
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/* give a chance to irqs before checking need_resched() */
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if (!((low_pfn+1) % SWAP_CLUSTER_MAX)) {
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spin_unlock_irq(&zone->lru_lock);
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locked = false;
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}
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if (need_resched() || spin_is_contended(&zone->lru_lock)) {
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if (locked)
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spin_unlock_irq(&zone->lru_lock);
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cond_resched();
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spin_lock_irq(&zone->lru_lock);
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if (fatal_signal_pending(current))
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break;
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} else if (!locked)
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spin_lock_irq(&zone->lru_lock);
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/*
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* migrate_pfn does not necessarily start aligned to a
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* pageblock. Ensure that pfn_valid is called when moving
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* into a new MAX_ORDER_NR_PAGES range in case of large
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* memory holes within the zone
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*/
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if ((low_pfn & (MAX_ORDER_NR_PAGES - 1)) == 0) {
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if (!pfn_valid(low_pfn)) {
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low_pfn += MAX_ORDER_NR_PAGES - 1;
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continue;
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}
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}
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if (!pfn_valid_within(low_pfn))
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continue;
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nr_scanned++;
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/*
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* Get the page and ensure the page is within the same zone.
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* See the comment in isolate_freepages about overlapping
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* nodes. It is deliberate that the new zone lock is not taken
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* as memory compaction should not move pages between nodes.
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*/
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page = pfn_to_page(low_pfn);
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if (page_zone(page) != zone)
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continue;
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/* Skip if free */
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if (PageBuddy(page))
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continue;
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/*
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* For async migration, also only scan in MOVABLE blocks. Async
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* migration is optimistic to see if the minimum amount of work
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* satisfies the allocation
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*/
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pageblock_nr = low_pfn >> pageblock_order;
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if (cc->mode != COMPACT_SYNC &&
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last_pageblock_nr != pageblock_nr &&
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!migrate_async_suitable(get_pageblock_migratetype(page))) {
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low_pfn += pageblock_nr_pages;
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low_pfn = ALIGN(low_pfn, pageblock_nr_pages) - 1;
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last_pageblock_nr = pageblock_nr;
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continue;
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}
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if (!PageLRU(page))
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continue;
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/*
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* PageLRU is set, and lru_lock excludes isolation,
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* splitting and collapsing (collapsing has already
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* happened if PageLRU is set).
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*/
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if (PageTransHuge(page)) {
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low_pfn += (1 << compound_order(page)) - 1;
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continue;
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}
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if (cc->mode != COMPACT_SYNC)
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mode |= ISOLATE_ASYNC_MIGRATE;
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/* Try isolate the page */
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if (__isolate_lru_page(page, mode, 0) != 0)
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continue;
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VM_BUG_ON(PageTransCompound(page));
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/* Successfully isolated */
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del_page_from_lru_list(zone, page, page_lru(page));
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list_add(&page->lru, migratelist);
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cc->nr_migratepages++;
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nr_isolated++;
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/* Avoid isolating too much */
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if (cc->nr_migratepages == COMPACT_CLUSTER_MAX) {
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++low_pfn;
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break;
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}
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}
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acct_isolated(zone, cc);
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spin_unlock_irq(&zone->lru_lock);
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trace_mm_compaction_isolate_migratepages(nr_scanned, nr_isolated);
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return low_pfn;
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}
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#endif /* CONFIG_COMPACTION || CONFIG_CMA */
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#ifdef CONFIG_COMPACTION
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/*
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* Returns true if MIGRATE_UNMOVABLE pageblock was successfully
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* converted to MIGRATE_MOVABLE type, false otherwise.
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*/
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static bool rescue_unmovable_pageblock(struct page *page)
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{
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unsigned long pfn, start_pfn, end_pfn;
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struct page *start_page, *end_page;
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pfn = page_to_pfn(page);
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start_pfn = pfn & ~(pageblock_nr_pages - 1);
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end_pfn = start_pfn + pageblock_nr_pages;
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start_page = pfn_to_page(start_pfn);
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end_page = pfn_to_page(end_pfn);
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/* Do not deal with pageblocks that overlap zones */
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if (page_zone(start_page) != page_zone(end_page))
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return false;
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for (page = start_page, pfn = start_pfn; page < end_page; pfn++,
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page++) {
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if (!pfn_valid_within(pfn))
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continue;
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if (PageBuddy(page)) {
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int order = page_order(page);
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pfn += (1 << order) - 1;
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page += (1 << order) - 1;
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continue;
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} else if (page_count(page) == 0 || PageLRU(page))
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continue;
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return false;
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}
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set_pageblock_migratetype(page, MIGRATE_MOVABLE);
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move_freepages_block(page_zone(page), page, MIGRATE_MOVABLE);
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return true;
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}
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enum smt_result {
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GOOD_AS_MIGRATION_TARGET,
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FAIL_UNMOVABLE_TARGET,
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FAIL_BAD_TARGET,
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};
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/*
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* Returns GOOD_AS_MIGRATION_TARGET if the page is within a block
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* suitable for migration to, FAIL_UNMOVABLE_TARGET if the page
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* is within a MIGRATE_UNMOVABLE block, FAIL_BAD_TARGET otherwise.
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*/
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static enum smt_result suitable_migration_target(struct page *page,
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struct compact_control *cc)
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{
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int migratetype = get_pageblock_migratetype(page);
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/* Don't interfere with memory hot-remove or the min_free_kbytes blocks */
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if (migratetype == MIGRATE_ISOLATE || migratetype == MIGRATE_RESERVE)
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return FAIL_BAD_TARGET;
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/* If the page is a large free page, then allow migration */
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if (PageBuddy(page) && page_order(page) >= pageblock_order)
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return GOOD_AS_MIGRATION_TARGET;
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/* If the block is MIGRATE_MOVABLE or MIGRATE_CMA, allow migration */
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if (cc->mode != COMPACT_ASYNC_UNMOVABLE &&
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migrate_async_suitable(migratetype))
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return GOOD_AS_MIGRATION_TARGET;
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if (cc->mode == COMPACT_ASYNC_MOVABLE &&
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migratetype == MIGRATE_UNMOVABLE)
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return FAIL_UNMOVABLE_TARGET;
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if (cc->mode != COMPACT_ASYNC_MOVABLE &&
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migratetype == MIGRATE_UNMOVABLE &&
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rescue_unmovable_pageblock(page))
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return GOOD_AS_MIGRATION_TARGET;
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/* Otherwise skip the block */
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return FAIL_BAD_TARGET;
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}
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/*
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* Based on information in the current compact_control, find blocks
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* suitable for isolating free pages from and then isolate them.
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*/
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static void isolate_freepages(struct zone *zone,
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struct compact_control *cc)
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{
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struct page *page;
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unsigned long high_pfn, low_pfn, pfn, zone_end_pfn, end_pfn;
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unsigned long flags;
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int nr_freepages = cc->nr_freepages;
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struct list_head *freelist = &cc->freepages;
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/*
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* Initialise the free scanner. The starting point is where we last
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* scanned from (or the end of the zone if starting). The low point
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* is the end of the pageblock the migration scanner is using.
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*/
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pfn = cc->free_pfn;
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|
low_pfn = cc->migrate_pfn + pageblock_nr_pages;
|
|
|
|
/*
|
|
* Take care that if the migration scanner is at the end of the zone
|
|
* that the free scanner does not accidentally move to the next zone
|
|
* in the next isolation cycle.
|
|
*/
|
|
high_pfn = min(low_pfn, pfn);
|
|
|
|
zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages;
|
|
|
|
/*
|
|
* isolate_freepages() may be called more than once during
|
|
* compact_zone_order() run and we want only the most recent
|
|
* count.
|
|
*/
|
|
cc->nr_pageblocks_skipped = 0;
|
|
|
|
/*
|
|
* Isolate free pages until enough are available to migrate the
|
|
* pages on cc->migratepages. We stop searching if the migrate
|
|
* and free page scanners meet or enough free pages are isolated.
|
|
*/
|
|
for (; pfn > low_pfn && cc->nr_migratepages > nr_freepages;
|
|
pfn -= pageblock_nr_pages) {
|
|
unsigned long isolated;
|
|
enum smt_result ret;
|
|
|
|
if (!pfn_valid(pfn))
|
|
continue;
|
|
|
|
/*
|
|
* Check for overlapping nodes/zones. It's possible on some
|
|
* configurations to have a setup like
|
|
* node0 node1 node0
|
|
* i.e. it's possible that all pages within a zones range of
|
|
* pages do not belong to a single zone.
|
|
*/
|
|
page = pfn_to_page(pfn);
|
|
if (page_zone(page) != zone)
|
|
continue;
|
|
|
|
/* Check the block is suitable for migration */
|
|
ret = suitable_migration_target(page, cc);
|
|
if (ret != GOOD_AS_MIGRATION_TARGET) {
|
|
if (ret == FAIL_UNMOVABLE_TARGET)
|
|
cc->nr_pageblocks_skipped++;
|
|
continue;
|
|
}
|
|
/*
|
|
* Found a block suitable for isolating free pages from. Now
|
|
* we disabled interrupts, double check things are ok and
|
|
* isolate the pages. This is to minimise the time IRQs
|
|
* are disabled
|
|
*/
|
|
isolated = 0;
|
|
spin_lock_irqsave(&zone->lock, flags);
|
|
ret = suitable_migration_target(page, cc);
|
|
if (ret == GOOD_AS_MIGRATION_TARGET) {
|
|
end_pfn = min(pfn + pageblock_nr_pages, zone_end_pfn);
|
|
isolated = isolate_freepages_block(pfn, end_pfn,
|
|
freelist, false);
|
|
nr_freepages += isolated;
|
|
} else if (ret == FAIL_UNMOVABLE_TARGET)
|
|
cc->nr_pageblocks_skipped++;
|
|
spin_unlock_irqrestore(&zone->lock, flags);
|
|
|
|
/*
|
|
* Record the highest PFN we isolated pages from. When next
|
|
* looking for free pages, the search will restart here as
|
|
* page migration may have returned some pages to the allocator
|
|
*/
|
|
if (isolated)
|
|
high_pfn = max(high_pfn, pfn);
|
|
}
|
|
|
|
/* split_free_page does not map the pages */
|
|
map_pages(freelist);
|
|
|
|
cc->free_pfn = high_pfn;
|
|
cc->nr_freepages = nr_freepages;
|
|
}
|
|
|
|
/*
|
|
* This is a migrate-callback that "allocates" freepages by taking pages
|
|
* from the isolated freelists in the block we are migrating to.
|
|
*/
|
|
static struct page *compaction_alloc(struct page *migratepage,
|
|
unsigned long data,
|
|
int **result)
|
|
{
|
|
struct compact_control *cc = (struct compact_control *)data;
|
|
struct page *freepage;
|
|
|
|
/* Isolate free pages if necessary */
|
|
if (list_empty(&cc->freepages)) {
|
|
isolate_freepages(cc->zone, cc);
|
|
|
|
if (list_empty(&cc->freepages))
|
|
return NULL;
|
|
}
|
|
|
|
freepage = list_entry(cc->freepages.next, struct page, lru);
|
|
list_del(&freepage->lru);
|
|
cc->nr_freepages--;
|
|
|
|
return freepage;
|
|
}
|
|
|
|
/*
|
|
* We cannot control nr_migratepages and nr_freepages fully when migration is
|
|
* running as migrate_pages() has no knowledge of compact_control. When
|
|
* migration is complete, we count the number of pages on the lists by hand.
|
|
*/
|
|
static void update_nr_listpages(struct compact_control *cc)
|
|
{
|
|
int nr_migratepages = 0;
|
|
int nr_freepages = 0;
|
|
struct page *page;
|
|
|
|
list_for_each_entry(page, &cc->migratepages, lru)
|
|
nr_migratepages++;
|
|
list_for_each_entry(page, &cc->freepages, lru)
|
|
nr_freepages++;
|
|
|
|
cc->nr_migratepages = nr_migratepages;
|
|
cc->nr_freepages = nr_freepages;
|
|
}
|
|
|
|
/* possible outcome of isolate_migratepages */
|
|
typedef enum {
|
|
ISOLATE_ABORT, /* Abort compaction now */
|
|
ISOLATE_NONE, /* No pages isolated, continue scanning */
|
|
ISOLATE_SUCCESS, /* Pages isolated, migrate */
|
|
} isolate_migrate_t;
|
|
|
|
/*
|
|
* Isolate all pages that can be migrated from the block pointed to by
|
|
* the migrate scanner within compact_control.
|
|
*/
|
|
static isolate_migrate_t isolate_migratepages(struct zone *zone,
|
|
struct compact_control *cc)
|
|
{
|
|
unsigned long low_pfn, end_pfn;
|
|
|
|
/* Do not scan outside zone boundaries */
|
|
low_pfn = max(cc->migrate_pfn, zone->zone_start_pfn);
|
|
|
|
/* Only scan within a pageblock boundary */
|
|
end_pfn = ALIGN(low_pfn + pageblock_nr_pages, pageblock_nr_pages);
|
|
|
|
/* Do not cross the free scanner or scan within a memory hole */
|
|
if (end_pfn > cc->free_pfn || !pfn_valid(low_pfn)) {
|
|
cc->migrate_pfn = end_pfn;
|
|
return ISOLATE_NONE;
|
|
}
|
|
|
|
/* Perform the isolation */
|
|
low_pfn = isolate_migratepages_range(zone, cc, low_pfn, end_pfn);
|
|
if (!low_pfn)
|
|
return ISOLATE_ABORT;
|
|
|
|
cc->migrate_pfn = low_pfn;
|
|
|
|
return ISOLATE_SUCCESS;
|
|
}
|
|
|
|
static int compact_finished(struct zone *zone,
|
|
struct compact_control *cc)
|
|
{
|
|
unsigned int order;
|
|
unsigned long watermark;
|
|
|
|
if (fatal_signal_pending(current))
|
|
return COMPACT_PARTIAL;
|
|
|
|
/* Compaction run completes if the migrate and free scanner meet */
|
|
if (cc->free_pfn <= cc->migrate_pfn)
|
|
return COMPACT_COMPLETE;
|
|
|
|
/*
|
|
* order == -1 is expected when compacting via
|
|
* /proc/sys/vm/compact_memory
|
|
*/
|
|
if (cc->order == -1)
|
|
return COMPACT_CONTINUE;
|
|
|
|
/* Compaction run is not finished if the watermark is not met */
|
|
watermark = low_wmark_pages(zone);
|
|
watermark += (1 << cc->order);
|
|
|
|
if (!zone_watermark_ok(zone, cc->order, watermark, 0, 0))
|
|
return COMPACT_CONTINUE;
|
|
|
|
/* Direct compactor: Is a suitable page free? */
|
|
for (order = cc->order; order < MAX_ORDER; order++) {
|
|
/* Job done if page is free of the right migratetype */
|
|
if (!list_empty(&zone->free_area[order].free_list[cc->migratetype]))
|
|
return COMPACT_PARTIAL;
|
|
|
|
/* Job done if allocation would set block type */
|
|
if (order >= pageblock_order && zone->free_area[order].nr_free)
|
|
return COMPACT_PARTIAL;
|
|
}
|
|
|
|
return COMPACT_CONTINUE;
|
|
}
|
|
|
|
/*
|
|
* compaction_suitable: Is this suitable to run compaction on this zone now?
|
|
* Returns
|
|
* COMPACT_SKIPPED - If there are too few free pages for compaction
|
|
* COMPACT_PARTIAL - If the allocation would succeed without compaction
|
|
* COMPACT_CONTINUE - If compaction should run now
|
|
*/
|
|
unsigned long compaction_suitable(struct zone *zone, int order)
|
|
{
|
|
int fragindex;
|
|
unsigned long watermark;
|
|
|
|
/*
|
|
* order == -1 is expected when compacting via
|
|
* /proc/sys/vm/compact_memory
|
|
*/
|
|
if (order == -1)
|
|
return COMPACT_CONTINUE;
|
|
|
|
/*
|
|
* Watermarks for order-0 must be met for compaction. Note the 2UL.
|
|
* This is because during migration, copies of pages need to be
|
|
* allocated and for a short time, the footprint is higher
|
|
*/
|
|
watermark = low_wmark_pages(zone) + (2UL << order);
|
|
if (!zone_watermark_ok(zone, 0, watermark, 0, 0))
|
|
return COMPACT_SKIPPED;
|
|
|
|
/*
|
|
* fragmentation index determines if allocation failures are due to
|
|
* low memory or external fragmentation
|
|
*
|
|
* index of -1000 implies allocations might succeed depending on
|
|
* watermarks
|
|
* index towards 0 implies failure is due to lack of memory
|
|
* index towards 1000 implies failure is due to fragmentation
|
|
*
|
|
* Only compact if a failure would be due to fragmentation.
|
|
*/
|
|
fragindex = fragmentation_index(zone, order);
|
|
if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold)
|
|
return COMPACT_SKIPPED;
|
|
|
|
if (fragindex == -1000 && zone_watermark_ok(zone, order, watermark,
|
|
0, 0))
|
|
return COMPACT_PARTIAL;
|
|
|
|
return COMPACT_CONTINUE;
|
|
}
|
|
|
|
static int compact_zone(struct zone *zone, struct compact_control *cc)
|
|
{
|
|
int ret;
|
|
|
|
ret = compaction_suitable(zone, cc->order);
|
|
switch (ret) {
|
|
case COMPACT_PARTIAL:
|
|
case COMPACT_SKIPPED:
|
|
/* Compaction is likely to fail */
|
|
return ret;
|
|
case COMPACT_CONTINUE:
|
|
/* Fall through to compaction */
|
|
;
|
|
}
|
|
|
|
/* Setup to move all movable pages to the end of the zone */
|
|
cc->migrate_pfn = zone->zone_start_pfn;
|
|
cc->free_pfn = cc->migrate_pfn + zone->spanned_pages;
|
|
cc->free_pfn &= ~(pageblock_nr_pages-1);
|
|
|
|
migrate_prep_local();
|
|
|
|
while ((ret = compact_finished(zone, cc)) == COMPACT_CONTINUE) {
|
|
unsigned long nr_migrate, nr_remaining;
|
|
int err;
|
|
|
|
switch (isolate_migratepages(zone, cc)) {
|
|
case ISOLATE_ABORT:
|
|
ret = COMPACT_PARTIAL;
|
|
goto out;
|
|
case ISOLATE_NONE:
|
|
continue;
|
|
case ISOLATE_SUCCESS:
|
|
;
|
|
}
|
|
|
|
nr_migrate = cc->nr_migratepages;
|
|
err = migrate_pages(&cc->migratepages, compaction_alloc,
|
|
(unsigned long)&cc->freepages, false,
|
|
(cc->mode == COMPACT_SYNC) ? MIGRATE_SYNC_LIGHT
|
|
: MIGRATE_ASYNC);
|
|
update_nr_listpages(cc);
|
|
nr_remaining = cc->nr_migratepages;
|
|
|
|
count_vm_event(COMPACTBLOCKS);
|
|
count_vm_events(COMPACTPAGES, nr_migrate - nr_remaining);
|
|
if (nr_remaining)
|
|
count_vm_events(COMPACTPAGEFAILED, nr_remaining);
|
|
trace_mm_compaction_migratepages(nr_migrate - nr_remaining,
|
|
nr_remaining);
|
|
|
|
/* Release LRU pages not migrated */
|
|
if (err) {
|
|
putback_lru_pages(&cc->migratepages);
|
|
cc->nr_migratepages = 0;
|
|
}
|
|
|
|
}
|
|
|
|
out:
|
|
/* Release free pages and check accounting */
|
|
cc->nr_freepages -= release_freepages(&cc->freepages);
|
|
VM_BUG_ON(cc->nr_freepages != 0);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static unsigned long compact_zone_order(struct zone *zone,
|
|
int order, gfp_t gfp_mask,
|
|
enum compact_mode mode,
|
|
unsigned long *nr_pageblocks_skipped)
|
|
{
|
|
struct compact_control cc = {
|
|
.nr_freepages = 0,
|
|
.nr_migratepages = 0,
|
|
.order = order,
|
|
.migratetype = allocflags_to_migratetype(gfp_mask),
|
|
.zone = zone,
|
|
.mode = mode,
|
|
};
|
|
unsigned long rc;
|
|
|
|
INIT_LIST_HEAD(&cc.freepages);
|
|
INIT_LIST_HEAD(&cc.migratepages);
|
|
|
|
rc = compact_zone(zone, &cc);
|
|
*nr_pageblocks_skipped = cc.nr_pageblocks_skipped;
|
|
|
|
return rc;
|
|
}
|
|
|
|
int sysctl_extfrag_threshold = 500;
|
|
|
|
/**
|
|
* try_to_compact_pages - Direct compact to satisfy a high-order allocation
|
|
* @zonelist: The zonelist used for the current allocation
|
|
* @order: The order of the current allocation
|
|
* @gfp_mask: The GFP mask of the current allocation
|
|
* @nodemask: The allowed nodes to allocate from
|
|
* @sync: Whether migration is synchronous or not
|
|
*
|
|
* This is the main entry point for direct page compaction.
|
|
*/
|
|
unsigned long try_to_compact_pages(struct zonelist *zonelist,
|
|
int order, gfp_t gfp_mask, nodemask_t *nodemask,
|
|
bool sync)
|
|
{
|
|
enum zone_type high_zoneidx = gfp_zone(gfp_mask);
|
|
int may_enter_fs = gfp_mask & __GFP_FS;
|
|
int may_perform_io = gfp_mask & __GFP_IO;
|
|
struct zoneref *z;
|
|
struct zone *zone;
|
|
int rc = COMPACT_SKIPPED;
|
|
unsigned long nr_pageblocks_skipped;
|
|
enum compact_mode mode;
|
|
|
|
/*
|
|
* Check whether it is worth even starting compaction. The order check is
|
|
* made because an assumption is made that the page allocator can satisfy
|
|
* the "cheaper" orders without taking special steps
|
|
*/
|
|
if (!order || !may_enter_fs || !may_perform_io)
|
|
return rc;
|
|
|
|
count_vm_event(COMPACTSTALL);
|
|
|
|
/* Compact each zone in the list */
|
|
for_each_zone_zonelist_nodemask(zone, z, zonelist, high_zoneidx,
|
|
nodemask) {
|
|
int status;
|
|
|
|
mode = sync ? COMPACT_SYNC : COMPACT_ASYNC_MOVABLE;
|
|
retry:
|
|
status = compact_zone_order(zone, order, gfp_mask, mode,
|
|
&nr_pageblocks_skipped);
|
|
rc = max(status, rc);
|
|
|
|
/* If a normal allocation would succeed, stop compacting */
|
|
if (zone_watermark_ok(zone, order, low_wmark_pages(zone), 0, 0))
|
|
break;
|
|
|
|
if (rc == COMPACT_COMPLETE && mode == COMPACT_ASYNC_MOVABLE) {
|
|
if (nr_pageblocks_skipped) {
|
|
mode = COMPACT_ASYNC_UNMOVABLE;
|
|
goto retry;
|
|
}
|
|
}
|
|
}
|
|
|
|
return rc;
|
|
}
|
|
|
|
|
|
/* Compact all zones within a node */
|
|
static int __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc)
|
|
{
|
|
int zoneid;
|
|
struct zone *zone;
|
|
|
|
for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
|
|
|
|
zone = &pgdat->node_zones[zoneid];
|
|
if (!populated_zone(zone))
|
|
continue;
|
|
|
|
cc->nr_freepages = 0;
|
|
cc->nr_migratepages = 0;
|
|
cc->zone = zone;
|
|
INIT_LIST_HEAD(&cc->freepages);
|
|
INIT_LIST_HEAD(&cc->migratepages);
|
|
|
|
if (cc->order == -1 || !compaction_deferred(zone, cc->order))
|
|
compact_zone(zone, cc);
|
|
|
|
if (cc->order > 0) {
|
|
int ok = zone_watermark_ok(zone, cc->order,
|
|
low_wmark_pages(zone), 0, 0);
|
|
if (ok && cc->order > zone->compact_order_failed)
|
|
zone->compact_order_failed = cc->order + 1;
|
|
/* Currently async compaction is never deferred. */
|
|
else if (!ok && cc->mode == COMPACT_SYNC)
|
|
defer_compaction(zone, cc->order);
|
|
}
|
|
|
|
VM_BUG_ON(!list_empty(&cc->freepages));
|
|
VM_BUG_ON(!list_empty(&cc->migratepages));
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
int compact_pgdat(pg_data_t *pgdat, int order)
|
|
{
|
|
struct compact_control cc = {
|
|
.order = order,
|
|
.mode = COMPACT_ASYNC_MOVABLE,
|
|
};
|
|
|
|
return __compact_pgdat(pgdat, &cc);
|
|
}
|
|
|
|
static int compact_node(int nid)
|
|
{
|
|
struct compact_control cc = {
|
|
.order = -1,
|
|
.mode = COMPACT_SYNC,
|
|
};
|
|
|
|
return __compact_pgdat(NODE_DATA(nid), &cc);
|
|
}
|
|
|
|
/* Compact all nodes in the system */
|
|
static int compact_nodes(void)
|
|
{
|
|
int nid;
|
|
|
|
/* Flush pending updates to the LRU lists */
|
|
lru_add_drain_all();
|
|
|
|
for_each_online_node(nid)
|
|
compact_node(nid);
|
|
|
|
return COMPACT_COMPLETE;
|
|
}
|
|
|
|
/* The written value is actually unused, all memory is compacted */
|
|
int sysctl_compact_memory;
|
|
|
|
/* This is the entry point for compacting all nodes via /proc/sys/vm */
|
|
int sysctl_compaction_handler(struct ctl_table *table, int write,
|
|
void __user *buffer, size_t *length, loff_t *ppos)
|
|
{
|
|
if (write)
|
|
return compact_nodes();
|
|
|
|
return 0;
|
|
}
|
|
|
|
int sysctl_extfrag_handler(struct ctl_table *table, int write,
|
|
void __user *buffer, size_t *length, loff_t *ppos)
|
|
{
|
|
proc_dointvec_minmax(table, write, buffer, length, ppos);
|
|
|
|
return 0;
|
|
}
|
|
|
|
#if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
|
|
ssize_t sysfs_compact_node(struct device *dev,
|
|
struct device_attribute *attr,
|
|
const char *buf, size_t count)
|
|
{
|
|
int nid = dev->id;
|
|
|
|
if (nid >= 0 && nid < nr_node_ids && node_online(nid)) {
|
|
/* Flush pending updates to the LRU lists */
|
|
lru_add_drain_all();
|
|
|
|
compact_node(nid);
|
|
}
|
|
|
|
return count;
|
|
}
|
|
static DEVICE_ATTR(compact, S_IWUSR, NULL, sysfs_compact_node);
|
|
|
|
int compaction_register_node(struct node *node)
|
|
{
|
|
return device_create_file(&node->dev, &dev_attr_compact);
|
|
}
|
|
|
|
void compaction_unregister_node(struct node *node)
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{
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return device_remove_file(&node->dev, &dev_attr_compact);
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}
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#endif /* CONFIG_SYSFS && CONFIG_NUMA */
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#endif /* CONFIG_COMPACTION */
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