user/sven/linux.git/include/linux/migrate.h, branch v3.2.78

mm: compaction: introduce sync-light migration for use by compaction

2012-08-02T13:37:32Z

commit a6bc32b899223a877f595ef9ddc1e89ead5072b8 upstream. Stable note: Not tracked in Buzilla. This was part of a series that reduced interactivity stalls experienced when THP was enabled. These stalls were particularly noticable when copying data to a USB stick but the experiences for users varied a lot. This patch adds a lightweight sync migrate operation MIGRATE_SYNC_LIGHT mode that avoids writing back pages to backing storage. Async compaction maps to MIGRATE_ASYNC while sync compaction maps to MIGRATE_SYNC_LIGHT. For other migrate_pages users such as memory hotplug, MIGRATE_SYNC is used. This avoids sync compaction stalling for an excessive length of time, particularly when copying files to a USB stick where there might be a large number of dirty pages backed by a filesystem that does not support ->writepages. [aarcange@redhat.com: This patch is heavily based on Andrea's work] [akpm@linux-foundation.org: fix fs/nfs/write.c build] [akpm@linux-foundation.org: fix fs/btrfs/disk-io.c build] Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel Cc: Andrea Arcangeli Cc: Minchan Kim Cc: Dave Jones Cc: Jan Kara Cc: Andy Isaacson Cc: Nai Xia Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings

mm: compaction: determine if dirty pages can be migrated without blocking within ->migratepage

2012-08-02T13:37:30Z

commit b969c4ab9f182a6e1b2a0848be349f99714947b0 upstream. Stable note: Not tracked in Bugzilla. A fix aimed at preserving page aging information by reducing LRU list churning had the side-effect of reducing THP allocation success rates. This was part of a series to restore the success rates while preserving the reclaim fix. Asynchronous compaction is used when allocating transparent hugepages to avoid blocking for long periods of time. Due to reports of stalling, there was a debate on disabling synchronous compaction but this severely impacted allocation success rates. Part of the reason was that many dirty pages are skipped in asynchronous compaction by the following check; if (PageDirty(page) && !sync && mapping->a_ops->migratepage != migrate_page) rc = -EBUSY; This skips over all mapping aops using buffer_migrate_page() even though it is possible to migrate some of these pages without blocking. This patch updates the ->migratepage callback with a "sync" parameter. It is the responsibility of the callback to fail gracefully if migration would block. Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel Cc: Andrea Arcangeli Cc: Minchan Kim Cc: Dave Jones Cc: Jan Kara Cc: Andy Isaacson Cc: Nai Xia Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings

mm: migration: cleanup migrate_pages API by matching types for offlining and sync

2011-01-14T01:32:34Z

With the introduction of the boolean sync parameter, the API looks a little inconsistent as offlining is still an int. Convert offlining to a bool for the sake of being tidy. Signed-off-by: Mel Gorman Cc: Andrea Arcangeli Cc: KOSAKI Motohiro Cc: Rik van Riel Acked-by: Johannes Weiner Cc: Andy Whitcroft Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: migration: allow migration to operate asynchronously and avoid synchronous compaction in the faster path

2011-01-14T01:32:34Z

Migration synchronously waits for writeback if the initial passes fails. Callers of memory compaction do not necessarily want this behaviour if the caller is latency sensitive or expects that synchronous migration is not going to have a significantly better success rate. This patch adds a sync parameter to migrate_pages() allowing the caller to indicate if wait_on_page_writeback() is allowed within migration or not. For reclaim/compaction, try_to_compact_pages() is first called asynchronously, direct reclaim runs and then try_to_compact_pages() is called synchronously as there is a greater expectation that it'll succeed. [akpm@linux-foundation.org: build/merge fix] Signed-off-by: Mel Gorman Cc: Andrea Arcangeli Cc: KOSAKI Motohiro Cc: Rik van Riel Acked-by: Johannes Weiner Cc: Andy Whitcroft Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Fix build error with !CONFIG_MIGRATION

2010-10-08T07:32:46Z

migrate_huge_page_move_mapping() is declared as "extern int ..." in include/linux/migrate.h for !CONFIG_MIGRATION, which causes the build error like below: mm/mprotect.o: In function `migrate_huge_page_move_mapping': mprotect.c:(.text+0x0): multiple definition of `migrate_huge_page_move_mapping' mm/shmem.o:shmem.c:(.text+0x0): first defined here mm/rmap.o: In function `migrate_huge_page_move_mapping': rmap.c:(.text+0x0): multiple definition of `migrate_huge_page_move_mapping' mm/shmem.o:shmem.c:(.text+0x0): first defined here Reported-by: Stephen Rothwell Signed-off-by: Naoya Horiguchi Signed-off-by: Andi Kleen

hugetlb: hugepage migration core

2010-10-08T07:32:45Z

This patch extends page migration code to support hugepage migration. One of the potential users of this feature is soft offlining which is triggered by memory corrected errors (added by the next patch.) Todo: - there are other users of page migration such as memory policy, memory hotplug and memocy compaction. They are not ready for hugepage support for now. ChangeLog since v4: - define migrate_huge_pages() - remove changes on isolation/putback_lru_page() ChangeLog since v2: - refactor isolate/putback_lru_page() to handle hugepage - add comment about race on unmap_and_move_huge_page() ChangeLog since v1: - divide migration code path for hugepage - define routine checking migration swap entry for hugetlb - replace "goto" with "if/else" in remove_migration_pte() Signed-off-by: Naoya Horiguchi Signed-off-by: Jun'ichi Nomura Acked-by: Mel Gorman Signed-off-by: Andi Kleen

mm: compaction: memory compaction core

2010-05-25T15:06:59Z

This patch is the core of a mechanism which compacts memory in a zone by relocating movable pages towards the end of the zone. A single compaction run involves a migration scanner and a free scanner. Both scanners operate on pageblock-sized areas in the zone. The migration scanner starts at the bottom of the zone and searches for all movable pages within each area, isolating them onto a private list called migratelist. The free scanner starts at the top of the zone and searches for suitable areas and consumes the free pages within making them available for the migration scanner. The pages isolated for migration are then migrated to the newly isolated free pages. [aarcange@redhat.com: Fix unsafe optimisation] [mel@csn.ul.ie: do not schedule work on other CPUs for compaction] Signed-off-by: Mel Gorman Acked-by: Rik van Riel Reviewed-by: Minchan Kim Cc: KOSAKI Motohiro Cc: Christoph Lameter Cc: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: remove return value of putback_lru_pages()

2010-05-25T15:06:57Z

putback_lru_page() never can fail. So it doesn't matter count of "the number of pages put back". In addition, users of this functions don't use return value. Let's remove unnecessary code. Signed-off-by: Minchan Kim Reviewed-by: Rik van Riel Reviewed-by: KOSAKI Motohiro Reviewed-by: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

ksm: memory hotremove migration only

2009-12-15T16:53:20Z

The previous patch enables page migration of ksm pages, but that soon gets into trouble: not surprising, since we're using the ksm page lock to lock operations on its stable_node, but page migration switches the page whose lock is to be used for that. Another layer of locking would fix it, but do we need that yet? Do we actually need page migration of ksm pages? Yes, memory hotremove needs to offline sections of memory: and since we stopped allocating ksm pages with GFP_HIGHUSER, they will tend to be GFP_HIGHUSER_MOVABLE candidates for migration. But KSM is currently unconscious of NUMA issues, happily merging pages from different NUMA nodes: at present the rule must be, not to use MADV_MERGEABLE where you care about NUMA. So no, NUMA page migration of ksm pages does not make sense yet. So, to complete support for ksm swapping we need to make hotremove safe. ksm_memory_callback() take ksm_thread_mutex when MEM_GOING_OFFLINE and release it when MEM_OFFLINE or MEM_CANCEL_OFFLINE. But if mapped pages are freed before migration reaches them, stable_nodes may be left still pointing to struct pages which have been removed from the system: the stable_node needs to identify a page by pfn rather than page pointer, then it can safely prune them when MEM_OFFLINE. And make NUMA migration skip PageKsm pages where it skips PageReserved. But it's only when we reach unmap_and_move() that the page lock is taken and we can be sure that raised pagecount has prevented a PageAnon from being upgraded: so add offlining arg to migrate_pages(), to migrate ksm page when offlining (has sufficient locking) but reject it otherwise. Signed-off-by: Hugh Dickins Cc: Izik Eidus Cc: Andrea Arcangeli Cc: Chris Wright Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: cleanup: remove #ifdef CONFIG_MIGRATION

2009-01-06T23:59:00Z

#ifdef in *.c file decrease source readability a bit. removing is better. This patch doesn't have any functional change. Signed-off-by: KOSAKI Motohiro Cc: Christoph Lameter Cc: Mel Gorman Cc: Lee Schermerhorn Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds