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linux/mm
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Andrea Arcangeli ba76149f47 thp: khugepaged 
Add khugepaged to relocate fragmented pages into hugepages if new
hugepages become available.  (this is indipendent of the defrag logic that
will have to make new hugepages available)

The fundamental reason why khugepaged is unavoidable, is that some memory
can be fragmented and not everything can be relocated.  So when a virtual
machine quits and releases gigabytes of hugepages, we want to use those
freely available hugepages to create huge-pmd in the other virtual
machines that may be running on fragmented memory, to maximize the CPU
efficiency at all times.  The scan is slow, it takes nearly zero cpu time,
except when it copies data (in which case it means we definitely want to
pay for that cpu time) so it seems a good tradeoff.

In addition to the hugepages being released by other process releasing
memory, we have the strong suspicion that the performance impact of
potentially defragmenting hugepages during or before each page fault could
lead to more performance inconsistency than allocating small pages at
first and having them collapsed into large pages later...  if they prove
themselfs to be long lived mappings (khugepaged scan is slow so short
lived mappings have low probability to run into khugepaged if compared to
long lived mappings).

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-01-13 17:32:43 -08:00
..
backing-dev.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2010-10-26 17:58:44 -07:00
bootmem.c x86, memblock: Replace e820_/_early string with memblock_ 2010-08-27 11:13:47 -07:00
bounce.c bounce: call flush_dcache_page() after bounce_copy_vec() 2010-09-09 18:57:25 -07:00
compaction.c mm: compaction: perform a faster migration scan when migrating asynchronously 2011-01-13 17:32:34 -08:00
debug-pagealloc.c generic debug pagealloc 2009-04-01 08:59:13 -07:00
dmapool.c mm: add a might_sleep_if() to dma_pool_alloc() 2010-10-26 16:52:08 -07:00
fadvise.c readahead: introduce FMODE_RANDOM for POSIX_FADV_RANDOM 2010-03-06 11:26:25 -08:00
failslab.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
filemap_xip.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
filemap.c mm: remove likely() from grab_cache_page_write_begin() 2011-01-13 17:32:36 -08:00
fremap.c Avoid pgoff overflow in remap_file_pages 2010-09-25 09:34:58 -07:00
highmem.c mm,x86: fix kmap_atomic_push vs ioremap_32.c 2010-10-27 18:03:05 -07:00
huge_memory.c thp: khugepaged 2011-01-13 17:32:43 -08:00
hugetlb.c thp: clear_copy_huge_page 2011-01-13 17:32:41 -08:00
hwpoison-inject.c HWPOISON, hugetlb: support hwpoison injection for hugepage 2010-08-11 09:23:11 +02:00
init-mm.c mm: provide init_mm mm_context initializer 2010-08-09 20:44:54 -07:00
internal.h thp: transparent hugepage core 2011-01-13 17:32:42 -08:00
Kconfig thp: CONFIG_TRANSPARENT_HUGEPAGE 2011-01-13 17:32:40 -08:00
Kconfig.debug trivial: improve help text for mm debug config options 2009-09-21 15:14:57 +02:00
kmemcheck.c kmemcheck: Fix build errors due to missing slab.h 2010-03-30 22:02:32 +09:00
kmemleak-test.c percpu: clean up percpu variable definitions 2009-06-24 15:13:48 +09:00
kmemleak.c kmemleak: Fix typo in the comment 2010-08-08 21:57:23 +01:00
ksm.c thp: ksm: free swap when swapcache page is replaced 2011-01-13 17:32:38 -08:00
maccess.c MN10300: Save frame pointer in thread_info struct rather than global var 2010-10-27 17:29:01 +01:00
madvise.c thp: madvise(MADV_HUGEPAGE) 2011-01-13 17:32:42 -08:00
Makefile thp: transparent hugepage core 2011-01-13 17:32:42 -08:00
memblock.c memblock: Annotate memblock functions with __init_memblock 2010-10-11 16:00:52 -07:00
memcontrol.c thp: transhuge-memcg: commit tail pages at charge 2011-01-13 17:32:43 -08:00
memory_hotplug.c mm: migration: cleanup migrate_pages API by matching types for offlining and sync 2011-01-13 17:32:34 -08:00
memory-failure.c thp: split_huge_page paging 2011-01-13 17:32:41 -08:00
memory.c thp: pmd_trans_huge migrate bugcheck 2011-01-13 17:32:42 -08:00
mempolicy.c thp: split_huge_page_mm/vma 2011-01-13 17:32:41 -08:00
mempool.c mm: remove broken 'kzalloc' mempool 2009-09-22 07:17:35 -07:00
migrate.c thp: pmd_trans_huge migrate bugcheck 2011-01-13 17:32:42 -08:00
mincore.c thp: split_huge_page_mm/vma 2011-01-13 17:32:41 -08:00
mlock.c mlock: do not hold mmap_sem for extended periods of time 2011-01-13 17:32:36 -08:00
mm_init.c mm: mminit_loglevel cannot be __meminitdata anymore 2008-08-20 15:40:30 -07:00
mmap.c install_special_mapping skips security_file_mmap check. 2010-12-15 12:30:36 -08:00
mmu_context.c exit: fix oops in sync_mm_rss 2010-03-24 16:31:21 -07:00
mmu_notifier.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mmzone.c mm: page allocator: adjust the per-cpu counter threshold when memory is low 2011-01-13 17:32:31 -08:00
mprotect.c thp: split_huge_page_mm/vma 2011-01-13 17:32:41 -08:00
mremap.c thp: split_huge_page_mm/vma 2011-01-13 17:32:41 -08:00
msync.c sanitize vfs_fsync calling conventions 2010-05-21 18:31:21 -04:00
nommu.c mlock: do not hold mmap_sem for extended periods of time 2011-01-13 17:32:36 -08:00
oom_kill.c oom: kill all threads sharing oom killed task's mm 2010-10-26 16:52:05 -07:00
page_alloc.c thp: don't alloc harder for gfp nomemalloc even if nowait 2011-01-13 17:32:42 -08:00
page_cgroup.c kmemleak: Annotate false positive in init_section_page_cgroup() 2010-07-19 11:54:14 +01:00
page_io.c block: unify flags for struct bio and struct request 2010-08-07 18:20:39 +02:00
page_isolation.c mm: page_isolation: codeclean fix comment and rm unneeded val init 2010-10-26 16:52:11 -07:00
page-writeback.c writeback: avoid unnecessary determine_dirtyable_memory call 2011-01-13 17:32:38 -08:00
pagewalk.c thp: split_huge_page_mm/vma 2011-01-13 17:32:41 -08:00
percpu-km.c percpu: clear memory allocated with the km allocator 2010-10-02 10:28:42 +03:00
percpu-vm.c mm: remove gfp mask from pcpu_get_vm_areas 2011-01-13 17:32:34 -08:00
percpu.c Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-01-13 10:05:56 -08:00
pgtable-generic.c thp: add pmd mangling generic functions 2011-01-13 17:32:40 -08:00
prio_tree.c
quicklist.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
readahead.c readahead.c: fix comment 2010-05-25 08:07:00 -07:00
rmap.c thp: transparent hugepage vmstat 2011-01-13 17:32:43 -08:00
shmem.c fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
slab.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6 2011-01-10 08:38:01 -08:00
slob.c kernel: kmem_ptr_validate considered harmful 2011-01-07 17:50:16 +11:00
slub.c mm: convert sprintf_symbol to %pS 2011-01-13 17:32:33 -08:00
sparse-vmemmap.c tree-wide: fix comment/printk typos 2010-11-01 15:38:34 -04:00
sparse.c sparsemem: on no vmemmap path put mem_map on node high too 2010-05-25 08:06:56 -07:00
swap_state.c thp: split_huge_page paging 2011-01-13 17:32:41 -08:00
swap.c thp: transparent hugepage core 2011-01-13 17:32:42 -08:00
swapfile.c thp: split_huge_page paging 2011-01-13 17:32:41 -08:00
thrash.c mm: pass mm to grab_swap_token 2009-06-23 12:50:05 -07:00
truncate.c Call the filesystem back whenever a page is removed from the page cache 2010-12-02 09:55:21 -05:00
util.c kernel: kmem_ptr_validate considered harmful 2011-01-07 17:50:16 +11:00
vmalloc.c vmalloc: remove redundant unlikely() 2011-01-13 17:32:36 -08:00
vmscan.c mm: kswapd: use the classzone idx that kswapd was using for sleeping_prematurely() 2011-01-13 17:32:37 -08:00
vmstat.c thp: transparent hugepage vmstat 2011-01-13 17:32:43 -08:00