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WSL2-Linux-Kernel
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WSL2-Linux-Kernel/mm
История
Taejoon Song 62bf1258ec mm/zswap: try to avoid worst-case scenario on same element pages 
The worst-case scenario on finding same element pages is that almost all
elements are same at the first glance but only last few elements are
different.

Since the same element tends to be grouped from the beginning of the
pages, if we check the first element with the last element before looping
through all elements, we might have some chances to quickly detect
non-same element pages.

1. Test is done under LG webOS TV (64-bit arch)
2. Dump the swap-out pages (~819200 pages)
3. Analyze the pages with simple test script which counts the iteration
   number and measures the speed at off-line

Under 64-bit arch, the worst iteration count is PAGE_SIZE / 8 bytes = 512.
The speed is based on the time to consume page_same_filled() function
only.  The result, on average, is listed as below:

                                   Num of Iter    Speed(MB/s)
Looping-Forward (Orig)                 38            99265
Looping-Backward                       36           102725
Last-element-check (This Patch)        33           125072

The result shows that the average iteration count decreases by 13% and the
speed increases by 25% with this patch.  This patch does not increase the
overall time complexity, though.

I also ran simpler version which uses backward loop.  Just looping
backward also makes some improvement, but less than this patch.

A similar change has already been made to zram in 90f82cbfe5 ("zram: try
to avoid worst-case scenario on same element pages").

Link: https://lkml.kernel.org/r/20230205190036.1730134-1-taejoon.song@lge.com
Signed-off-by: Taejoon Song <taejoon.song@lge.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Taejoon Song <taejoon.song@lge.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: <yjay.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 		2023-03-28 16:20:07 -07:00
..
damon mm/damon/paddr: fix folio_nr_pages() after folio_put() in damon_pa_mark_accessed_or_deactivate() 2023-03-07 17:04:55 -08:00
kasan kasan: test: fix test for new meminstrinsic instrumentation 2023-03-02 21:54:22 -08:00
kfence mm: kfence: fix handling discontiguous page 2023-03-28 15:24:32 -07:00
kmsan kmsan: disable ftrace in kmsan core code 2023-02-20 12:46:16 -08:00
Kconfig zsmalloc: set default zspage chain size to 8 2023-02-02 22:33:23 -08:00
Kconfig.debug mm: move KMEMLEAK's Kconfig items from lib to mm 2023-02-02 22:33:26 -08:00
Makefile mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol 2022-10-03 14:03:36 -07:00
backing-dev.c mm: add /sys/class/bdi/<bdi>/min_ratio_fine knob 2022-11-30 15:59:06 -08:00
balloon_compaction.c mm: Convert all PageMovable users to movable_operations 2022-08-02 12:34:03 -04:00
bootmem_info.c bootmem: remove the vmemmap pages from kmemleak in put_page_bootmem 2022-08-28 14:02:45 -07:00
cma.c mm/cma: fix potential memory loss on cma_declare_contiguous_nid 2023-02-02 22:33:24 -08:00
cma.h
…
cma_debug.c mm/cma_debug: show complete cma name in debugfs directories 2022-09-11 20:25:50 -07:00
cma_sysfs.c mm: cma: make kobj_type structure constant 2023-03-28 16:20:06 -07:00
compaction.c - Daniel Verkamp has contributed a memfd series ("mm/memfd: add 2023-02-23 17:09:35 -08:00
debug.c mm: export dump_mm() 2023-02-09 16:51:40 -08:00
debug_page_ref.c
…
debug_vm_pgtable.c mm: remove __HAVE_ARCH_PTE_SWP_EXCLUSIVE 2023-02-02 22:33:11 -08:00
dmapool.c
…
early_ioremap.c
…
fadvise.c mm: support POSIX_FADV_NOREUSE 2023-01-18 17:12:57 -08:00
failslab.c mm: fix unexpected changes to {failslab|fail_page_alloc}.attr 2022-11-22 18:50:44 -08:00
filemap.c - Daniel Verkamp has contributed a memfd series ("mm/memfd: add 2023-02-23 17:09:35 -08:00
folio-compat.c mm: change to return bool for isolate_lru_page() 2023-02-20 12:46:17 -08:00
frontswap.c frontswap: don't call ->init if no ops are registered 2022-09-26 12:14:34 -07:00
gup.c mm: change to return bool for folio_isolate_lru() 2023-02-20 12:46:17 -08:00
gup_test.c mm/gup_test: free memory allocated via kvcalloc() using kvfree() 2022-12-15 16:37:48 -08:00
gup_test.h mm/gup_test: start/stop/read functionality for PIN LONGTERM test 2022-11-08 17:37:15 -08:00
highmem.c highmem: fix kmap_to_page() for kmap_local_page() addresses 2022-10-12 18:51:51 -07:00
hmm.c mm/hugetlb: make walk_hugetlb_range() safe to pmd unshare 2023-01-18 17:12:39 -08:00
huge_memory.c mm/userfaultfd: propagate uffd-wp bit when PTE-mapping the huge zeropage 2023-03-07 17:04:53 -08:00
hugetlb.c mm: hugetlb: change to return bool for isolate_hugetlb() 2023-02-20 12:46:17 -08:00
hugetlb_cgroup.c mm/hugetlb: increase use of folios in alloc_huge_page() 2023-02-13 15:54:27 -08:00
hugetlb_vmemmap.c mm: hugetlb_vmemmap: simplify hugetlb_vmemmap_init() a bit 2023-03-28 16:20:06 -07:00
hugetlb_vmemmap.h mm: hugetlb_vmemmap: improve hugetlb_vmemmap code readability 2022-08-08 18:06:43 -07:00
hwpoison-inject.c mm/hwpoison: add __init/__exit annotations to module init/exit funcs 2022-10-03 14:03:05 -07:00
init-mm.c mm: remove rb tree. 2022-09-26 19:46:16 -07:00
internal.h - Daniel Verkamp has contributed a memfd series ("mm/memfd: add 2023-02-23 17:09:35 -08:00
interval_tree.c
…
io-mapping.c
…
ioremap.c
…
khugepaged.c mm/khugepaged: alloc_charge_hpage() take care of mem charge errors 2023-03-28 16:20:06 -07:00
kmemleak.c lib/stackdepot, mm: rename stack_depot_want_early_init 2023-02-16 20:43:49 -08:00
ksm.c mm/ksm: fix race with VMA iteration and mm_struct teardown 2023-03-23 17:18:33 -07:00
list_lru.c
…
maccess.c maccess: Fix writing offset in case of fault in strncpy_from_kernel_nofault() 2022-11-11 11:44:46 -08:00
madvise.c - Daniel Verkamp has contributed a memfd series ("mm/memfd: add 2023-02-23 17:09:35 -08:00
mapping_dirty_helpers.c mm/mmu_notifier: remove unused mmu_notifier_range_update_to_read_only export 2023-02-02 22:32:54 -08:00
memblock.c memblock: small optimizations 2023-02-27 09:34:53 -08:00
memcontrol.c - Daniel Verkamp has contributed a memfd series ("mm/memfd: add 2023-02-23 17:09:35 -08:00
memfd.c mm/memfd: add write seals when apply SEAL_EXEC to executable memfd 2023-01-18 17:12:37 -08:00
memory-failure.c mm/hwpoison: convert TTU_IGNORE_HWPOISON to TTU_HWPOISON 2023-02-27 17:00:14 -08:00
memory-tiers.c memory tier: release the new_memtier in find_create_memory_tier() 2023-02-09 16:51:40 -08:00
memory.c x86/mm/pat: clear VM_PAT if copy_p4d_range failed 2023-03-28 16:20:07 -07:00
memory_hotplug.c mm/memory_hotplug: cleanup return value handing in do_migrate_range() 2023-02-20 12:46:18 -08:00
mempolicy.c mm: hugetlb: change to return bool for isolate_hugetlb() 2023-02-20 12:46:17 -08:00
mempool.c mempool: do not use ksize() for poisoning 2022-11-30 15:58:41 -08:00
memremap.c mm/memremap.c: fix outdated comment in devm_memremap_pages 2023-02-09 16:51:46 -08:00
memtest.c
…
migrate.c migrate_pages: try migrate in batch asynchronously firstly 2023-03-07 17:04:54 -08:00
migrate_device.c mm: change to return bool for isolate_lru_page() 2023-02-20 12:46:17 -08:00
mincore.c mm: teach mincore_hugetlb about pte markers 2023-03-07 17:04:53 -08:00
mlock.c mm: introduce vm_flags_reset_once to replace WRITE_ONCE vm_flags updates 2023-02-09 16:51:41 -08:00
mm_init.c memory: move hotplug memory notifier priority to same file for easy sorting 2022-11-08 17:37:17 -08:00
mm_slot.h mm: introduce common struct mm_slot 2022-10-03 14:02:43 -07:00
mmap.c mm: deduplicate error handling for map_deny_write_exec 2023-03-23 17:18:32 -07:00
mmap_lock.c
…
mmu_gather.c mm: mmu_gather: allow more than one batch of delayed rmaps 2022-12-11 18:12:21 -08:00
mmu_notifier.c mm/mmu_notifier: remove unused mmu_notifier_range_update_to_read_only export 2023-02-02 22:32:54 -08:00
mmzone.c mm: multi-gen LRU: groundwork 2022-09-26 19:46:09 -07:00
mprotect.c mm: fix error handling for map_deny_write_exec 2023-03-23 17:18:33 -07:00
mremap.c x86/mm/pat: clear VM_PAT if copy_p4d_range failed 2023-03-28 16:20:07 -07:00
msync.c mm/msync: use vma_find() instead of vma linked list 2022-09-26 19:46:25 -07:00
nommu.c mm: replace vma->vm_flags direct modifications with modifier calls 2023-02-09 16:51:39 -08:00
oom_kill.c mm/mmu_notifier: remove unused mmu_notifier_range_update_to_read_only export 2023-02-02 22:32:54 -08:00
page-writeback.c fs: convert writepage_t callback to pass a folio 2023-02-02 22:33:34 -08:00
page_alloc.c mm, page_alloc: reduce page alloc/free sanity checks 2023-03-28 16:20:06 -07:00
page_counter.c mm: page_counter: remove unneeded atomic ops for low/min 2022-09-11 20:26:01 -07:00
page_ext.c mm/page_ext: init page_ext early if there are no deferred struct pages 2023-02-02 22:33:22 -08:00
page_idle.c mm: page_idle: convert page idle to use a folio 2023-01-18 17:12:52 -08:00
page_io.c - Daniel Verkamp has contributed a memfd series ("mm/memfd: add 2023-02-23 17:09:35 -08:00
page_isolation.c mm/page_isolation: fix clang deadcode warning 2022-10-28 13:37:22 -07:00
page_owner.c lib/stackdepot, mm: rename stack_depot_want_early_init 2023-02-16 20:43:49 -08:00
page_poison.c
…
page_reporting.c mm/page_reporting: replace rcu_access_pointer() with rcu_dereference_protected() 2023-01-18 17:12:50 -08:00
page_reporting.h
…
page_table_check.c mm/page_ext: do not allocate space for page_ext->flags if not needed 2023-02-02 22:33:11 -08:00
page_vma_mapped.c mm/hugetlb: introduce hugetlb_walk() 2023-01-18 17:12:39 -08:00
pagewalk.c mm/hugetlb: introduce hugetlb_walk() 2023-01-18 17:12:39 -08:00
percpu-internal.h mm: percpu: fix incorrect size in pcpu_obj_full_size() 2023-02-16 20:43:55 -08:00
percpu-km.c
…
percpu-stats.c
…
percpu-vm.c
…
percpu.c mm: memcontrol: rename memcg_kmem_enabled() 2023-02-16 20:43:56 -08:00
pgalloc-track.h
…
pgtable-generic.c
…
process_vm_access.c use less confusing names for iov_iter direction initializers 2022-11-25 13:01:55 -05:00
ptdump.c mm: pagewalk: Fix race between unmap and page walker 2022-09-03 10:13:13 -07:00
readahead.c readahead: convert readahead_expand() to use a folio 2023-02-02 22:33:21 -08:00
rmap.c mm/hwpoison: convert TTU_IGNORE_HWPOISON to TTU_HWPOISON 2023-02-27 17:00:14 -08:00
rodata_test.c mm/rodata_test: use PAGE_ALIGNED() helper 2022-10-03 14:03:05 -07:00
secretmem.c - Daniel Verkamp has contributed a memfd series ("mm/memfd: add 2023-02-23 17:09:35 -08:00
shmem.c - Daniel Verkamp has contributed a memfd series ("mm/memfd: add 2023-02-23 17:09:35 -08:00
shrinker_debug.c mm: shrinkers: fix deadlock in shrinker debugfs 2023-02-09 15:56:51 -08:00
shuffle.c mm/shuffle: convert module_param_call to module_param_cb 2022-10-03 14:03:07 -07:00
shuffle.h
…
slab.c slab fix for 6.3-rc4 2023-03-24 10:12:14 -07:00
slab.h mm: memcontrol: rename memcg_kmem_enabled() 2023-02-16 20:43:56 -08:00
slab_common.c mm/kasan: simplify and refine kasan_cache code 2023-01-18 17:12:55 -08:00
slob.c Merge branch 'slab/for-6.1/kmalloc_size_roundup' into slab/for-next 2022-09-29 11:30:55 +02:00
slub.c - Daniel Verkamp has contributed a memfd series ("mm/memfd: add 2023-02-23 17:09:35 -08:00
sparse-vmemmap.c mm/sparse-vmemmap: generalise vmemmap_populate_hugepages() 2022-12-11 18:12:12 -08:00
sparse.c mm/sparse: fix "unused function 'pgdat_to_phys'" warning 2023-02-02 22:33:29 -08:00
swap.c - Daniel Verkamp has contributed a memfd series ("mm/memfd: add 2023-02-23 17:09:35 -08:00
swap.h mm: remove the __swap_writepage return value 2023-02-02 22:33:33 -08:00
swap_cgroup.c mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled 2022-10-03 14:03:36 -07:00
swap_slots.c mm/swap: convert put_swap_page() to put_swap_folio() 2022-10-03 14:02:46 -07:00
swap_state.c swap_state: update shadow_nodes for anonymous page 2023-02-02 22:33:24 -08:00
swapfile.c - Daniel Verkamp has contributed a memfd series ("mm/memfd: add 2023-02-23 17:09:35 -08:00
truncate.c folio-compat: remove lru_cache_add() 2022-12-11 18:12:13 -08:00
usercopy.c mm: use kstrtobool() instead of strtobool() 2022-11-30 15:58:45 -08:00
userfaultfd.c mm/userfaultfd: support WP on multiple VMAs 2023-03-28 16:20:07 -07:00
util.c mm: fix typo in __vm_enough_memory warning 2023-02-13 15:54:33 -08:00
vmalloc.c mm, vmalloc: fix high order __GFP_NOFAIL allocations 2023-03-23 17:18:31 -07:00
vmpressure.c
…
vmscan.c mm: multi-gen LRU: improve design doc 2023-03-28 16:20:07 -07:00
vmstat.c mm: vmscan: split khugepaged stats from direct reclaim stats 2022-11-30 15:58:41 -08:00
workingset.c swap_state: update shadow_nodes for anonymous page 2023-02-02 22:33:24 -08:00
z3fold.c mm: remove PageMovable export 2023-01-18 17:12:57 -08:00
zbud.c zpool: clean out dead code 2022-12-11 18:12:10 -08:00
zpool.c zpool: clean out dead code 2022-12-11 18:12:10 -08:00
zsmalloc.c zsmalloc: make zspage chain size configurable 2023-02-02 22:33:23 -08:00
zswap.c mm/zswap: try to avoid worst-case scenario on same element pages 2023-03-28 16:20:07 -07:00