linux/mm
Mel Gorman 09a913a7a9 sched/numa: avoid trapping faults and attempting migration of file-backed dirty pages
change_pte_range is called from task work context to mark PTEs for
receiving NUMA faulting hints.  If the marked pages are dirty then
migration may fail.  Some filesystems cannot migrate dirty pages without
blocking so are skipped in MIGRATE_ASYNC mode which just wastes CPU.
Even when they can, it can be a waste of cycles when the pages are
shared forcing higher scan rates.  This patch avoids marking shared
dirty pages for hinting faults but also will skip a migration if the
page was dirtied after the scanner updated a clean page.

This is most noticeable running the NASA Parallel Benchmark when backed
by btrfs, the default root filesystem for some distributions, but also
noticeable when using XFS.

The following are results from a 4-socket machine running a 4.16-rc4
kernel with some scheduler patches that are pending for the next merge
window.

                        4.16.0-rc4             4.16.0-rc4
                 schedtip-20180309          nodirty-v1
  Time cg.D      459.07 (   0.00%)      444.21 (   3.24%)
  Time ep.D       76.96 (   0.00%)       77.69 (  -0.95%)
  Time is.D       25.55 (   0.00%)       27.85 (  -9.00%)
  Time lu.D      601.58 (   0.00%)      596.87 (   0.78%)
  Time mg.D      107.73 (   0.00%)      108.22 (  -0.45%)

is.D regresses slightly in terms of absolute time but note that that
particular load varies quite a bit from run to run.  The more relevant
observation is the total system CPU usage.

            4.16.0-rc4  4.16.0-rc4
          schedtip-20180309 nodirty-v1
  User        71471.91    70627.04
  System      11078.96     8256.13
  Elapsed       661.66      632.74

That is a substantial drop in system CPU usage and overall the workload
completes faster.  The NUMA balancing statistics are also interesting

  NUMA base PTE updates        111407972   139848884
  NUMA huge PMD updates           206506      264869
  NUMA page range updates      217139044   275461812
  NUMA hint faults               4300924     3719784
  NUMA hint local faults         3012539     3416618
  NUMA hint local percent             70          91
  NUMA pages migrated            1517487     1358420

While more PTEs are scanned due to changes in what faults are gathered,
it's clear that a far higher percentage of faults are local as the bulk
of the remote hits were dirty pages that, in this case with btrfs, had
no chance of migrating.

The following is a comparison when using XFS as that is a more realistic
filesystem choice for a data partition

                        4.16.0-rc4             4.16.0-rc4
                 schedtip-20180309          nodirty-v1r47
  Time cg.D      485.28 (   0.00%)      442.62 (   8.79%)
  Time ep.D       77.68 (   0.00%)       77.54 (   0.18%)
  Time is.D       26.44 (   0.00%)       24.79 (   6.24%)
  Time lu.D      597.46 (   0.00%)      597.11 (   0.06%)
  Time mg.D      142.65 (   0.00%)      105.83 (  25.81%)

That is a reasonable gain on two relatively long-lived workloads.  While
not presented, there is also a substantial drop in system CPu usage and
the NUMA balancing stats show similar improvements in locality as btrfs
did.

Link: http://lkml.kernel.org/r/20180326094334.zserdec62gwmmfqf@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11 10:28:31 -07:00
..
kasan slab, slub: skip unnecessary kasan_cache_shutdown() 2018-04-05 21:36:24 -07:00
backing-dev.c mm/vmscan: don't mess with pgdat->flags in memcg reclaim 2018-04-11 10:28:30 -07:00
balloon_compaction.c
bootmem.c mm: docs: fix parameter names mismatch 2018-02-06 18:32:48 -08:00
cleancache.c
cma_debug.c
cma.c headers: untangle kmemleak.h from mm.h 2018-04-05 21:36:27 -07:00
cma.h
compaction.c mm: kernel-doc: add missing parameter descriptions 2018-04-05 21:36:27 -07:00
debug_page_ref.c
debug.c mm/debug.c: provide useful debugging information for VM_BUG 2018-01-04 16:45:09 -08:00
dmapool.c
early_ioremap.c mm/early_ioremap: Fix boot hang with earlyprintk=efi,keep 2017-12-11 14:54:44 +01:00
fadvise.c mm: add ksys_fadvise64_64() helper; remove in-kernel call to sys_fadvise64_64() 2018-04-02 20:16:10 +02:00
failslab.c mm: make should_failslab always available for fault injection 2018-04-05 21:36:26 -07:00
filemap.c mm/filemap.c: remove include of hardirq.h 2018-01-31 17:18:36 -08:00
frame_vector.c mm/frame_vector.c: release a semaphore in 'get_vaddr_frames()' 2017-12-14 16:00:48 -08:00
frontswap.c
gup_benchmark.c mm: add infrastructure for get_user_pages_fast() benchmarking 2017-11-17 16:10:04 -08:00
gup.c mm/gup.c: fix coding style issues. 2018-04-05 21:36:26 -07:00
highmem.c
hmm.c mm/hmm.c: remove superfluous RCU protection around radix tree lookup 2018-04-11 10:28:31 -07:00
huge_memory.c mm/huge_memory.c: reorder operations in __split_huge_page_tail() 2018-04-05 21:36:25 -07:00
hugetlb_cgroup.c
hugetlb.c mm, hugetlbfs: introduce ->pagesize() to vm_operations_struct 2018-04-05 21:36:26 -07:00
hwpoison-inject.c mm/memory_failure: Remove unused trapno from memory_failure 2018-01-23 12:17:42 -06:00
init-mm.c
internal.h Revert "mm, thp: Do not make pmd/pud dirty without a reason" 2017-11-29 09:01:01 -08:00
interval_tree.c mm/interval_tree.c: use vma_pages() helper 2018-01-31 17:18:37 -08:00
Kconfig treewide: simplify Kconfig dependencies for removed archs 2018-03-26 15:55:57 +02:00
Kconfig.debug kmemcheck: rip it out 2017-11-15 18:21:05 -08:00
khugepaged.c mm, thp: do not cause memcg oom for thp 2018-03-22 17:07:02 -07:00
kmemleak-test.c
kmemleak.c mm: kernel-doc: add missing parameter descriptions 2018-04-05 21:36:27 -07:00
ksm.c mm/ksm: fix interaction with THP 2018-04-05 21:36:27 -07:00
list_lru.c mm: make counting of list_lru_one::nr_items lockless 2018-04-05 21:36:27 -07:00
maccess.c mm: docs: fix parameter names mismatch 2018-02-06 18:32:48 -08:00
madvise.c mm/memory_failure: Remove unused trapno from memory_failure 2018-01-23 12:17:42 -06:00
Makefile mm/swap_slots.c: use conditional compilation 2018-04-05 21:36:24 -07:00
memblock.c powerpc updates for 4.17 2018-04-07 12:08:19 -07:00
memcontrol.c mm/memcontrol.c: fix parameter description mismatch 2018-03-28 13:42:05 -10:00
memory_hotplug.c mm: kernel-doc: add missing parameter descriptions 2018-04-05 21:36:27 -07:00
memory-failure.c mm: hwpoison: disable memory error handling on 1GB hugepage 2018-04-05 21:36:25 -07:00
memory.c mm: swap: unify cluster-based and vma-based swap readahead 2018-04-05 21:36:25 -07:00
mempolicy.c Merge branch 'syscalls-next' of git://git.kernel.org/pub/scm/linux/kernel/git/brodo/linux 2018-04-02 21:22:12 -07:00
mempool.c kasan: detect invalid frees for large mempool objects 2018-02-06 18:32:43 -08:00
memtest.c
migrate.c sched/numa: avoid trapping faults and attempting migration of file-backed dirty pages 2018-04-11 10:28:31 -07:00
mincore.c
mlock.c mm, mlock, vmscan: no more skipping pagevecs 2018-02-21 15:35:42 -08:00
mm_init.c
mmap.c mm: always print RLIMIT_DATA warning 2018-04-05 21:36:24 -07:00
mmu_context.c
mmu_notifier.c mm, mmu_notifier: annotate mmu notifiers with blockable invalidate callbacks 2018-01-31 17:18:38 -08:00
mmzone.c
mprotect.c sched/numa: avoid trapping faults and attempting migration of file-backed dirty pages 2018-04-11 10:28:31 -07:00
mremap.c
msync.c
nobootmem.c
nommu.c mm/nommu: remove description of alloc_vm_area 2018-04-05 21:36:26 -07:00
oom_kill.c mm,oom_reaper: check for MMF_OOM_SKIP before complaining 2018-04-05 21:36:27 -07:00
page_alloc.c mm: treat indirectly reclaimable memory as available in MemAvailable 2018-04-11 10:28:29 -07:00
page_counter.c
page_ext.c mm/page_ext.c: make page_ext_init a noop when CONFIG_PAGE_EXTENSION but nothing uses it 2018-01-31 17:18:39 -08:00
page_idle.c mm: thp: fix potential clearing to referenced flag in page_idle_clear_pte_refs_one() 2018-04-05 21:36:25 -07:00
page_io.c block: convert to bio_first_bvec_all & bio_first_page_all 2018-01-06 09:18:00 -07:00
page_isolation.c mm/page_isolation.c: make start_isolate_page_range() fail if already isolated 2018-04-05 21:36:27 -07:00
page_owner.c mm/page_owner.c: make early_page_owner_param() __init 2018-04-05 21:36:26 -07:00
page_poison.c mm/page_poison.c: make early_page_poison_param() __init 2018-04-05 21:36:26 -07:00
page_vma_mapped.c mm, page_vma_mapped: Introduce pfn_in_hpage() 2018-01-22 12:15:57 -08:00
page-writeback.c Revert "mm/page-writeback.c: print a warning if the vm dirtiness settings are illogical" 2017-11-29 18:40:43 -08:00
pagewalk.c mm: kernel-doc: add missing parameter descriptions 2018-04-05 21:36:27 -07:00
percpu-internal.h
percpu-km.c percpu: allow select gfp to be passed to underlying allocators 2018-02-18 05:33:01 -08:00
percpu-stats.c mm: reuse DEFINE_SHOW_ATTRIBUTE() macro 2018-04-05 21:36:25 -07:00
percpu-vm.c percpu: allow select gfp to be passed to underlying allocators 2018-02-18 05:33:01 -08:00
percpu.c arch: remove obsolete architecture ports 2018-04-02 20:20:12 -07:00
pgtable-generic.c mm: do not lose dirty and accessed bits in pmdp_invalidate() 2018-01-31 17:18:38 -08:00
process_vm_access.c mm: docs: add blank lines to silence sphinx "Unexpected indentation" errors 2018-02-06 18:32:48 -08:00
quicklist.c
readahead.c mm: add ksys_readahead() helper; remove in-kernel calls to sys_readahead() 2018-04-02 20:16:12 +02:00
rmap.c mm: kernel-doc: add missing parameter descriptions 2018-04-05 21:36:27 -07:00
rodata_test.c
shmem.c mm: swap: unify cluster-based and vma-based swap readahead 2018-04-05 21:36:25 -07:00
slab_common.c mm: make should_failslab always available for fault injection 2018-04-05 21:36:26 -07:00
slab.c slab, slub: skip unnecessary kasan_cache_shutdown() 2018-04-05 21:36:24 -07:00
slab.h slab, slub: skip unnecessary kasan_cache_shutdown() 2018-04-05 21:36:24 -07:00
slob.c slab, slub, slob: add slab_flags_t 2017-11-15 18:21:01 -08:00
slub.c slab, slub: skip unnecessary kasan_cache_shutdown() 2018-04-05 21:36:24 -07:00
sparse-vmemmap.c mm: merge vmem_altmap_alloc into altmap_alloc_block_buf 2018-01-08 11:46:23 -08:00
sparse.c mm/memory_hotplug: optimize memory hotplug 2018-04-05 21:36:25 -07:00
swap_cgroup.c
swap_slots.c mm/swap_slots.c: use conditional compilation 2018-04-05 21:36:24 -07:00
swap_state.c mm/swap_state.c: make bool enable_vma_readahead and swap_vma_readahead() static 2018-04-05 21:36:27 -07:00
swap.c mm/swap.c: remove @cold parameter description for release_pages() 2018-04-05 21:36:26 -07:00
swapfile.c vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
truncate.c mm: add unmap_mapping_pages() 2018-01-31 17:18:37 -08:00
usercopy.c usercopy: WARN() on slab cache usercopy region violations 2018-01-15 12:07:48 -08:00
userfaultfd.c mm/userfaultfd.c: remove duplicate include 2018-02-06 18:32:47 -08:00
util.c mm: treat indirectly reclaimable memory as free in overcommit logic 2018-04-11 10:28:29 -07:00
vmacache.c
vmalloc.c vmalloc: fix __GFP_HIGHMEM usage for vmalloc_32 on 32b systems 2018-02-21 15:35:43 -08:00
vmpressure.c
vmscan.c mm, vmscan, tracing: use pointer to reclaim_stat struct in trace event 2018-04-11 10:28:30 -07:00
vmstat.c mm: introduce NR_INDIRECTLY_RECLAIMABLE_BYTES 2018-04-11 10:28:29 -07:00
workingset.c mm, truncate: do not check mapping for every page being truncated 2017-11-15 18:21:06 -08:00
z3fold.c z3fold: limit use of stale list for allocation 2018-04-05 21:36:25 -07:00
zbud.c mm: docs: fix parameter names mismatch 2018-02-06 18:32:48 -08:00
zpool.c mm/zpool.c: zpool_evictable: fix mismatch in parameter name and kernel-doc 2018-02-21 15:35:43 -08:00
zsmalloc.c mm: kernel-doc: add missing parameter descriptions 2018-04-05 21:36:27 -07:00
zswap.c mm, swap, frontswap: fix THP swap if frontswap enabled 2018-02-21 15:35:43 -08:00