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c4d91e225f
linux/mm
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Lorenzo Stoakes c4d91e225f mm/vma: add expand-only VMA merge mode and optimise do_brk_flags() 
Patch series "introduce VMA merge mode to improve brk() performance".

A ~5% performance regression was discovered on the
aim9.brk_test.ops_per_sec by the linux kernel test bot [0].

In the past to satisfy brk() performance we duplicated VMA expansion code
and special-cased do_brk_flags().  This is however horrid and undoes work
to abstract this logic, so in resolving the issue I have endeavoured to
avoid this.

Investigating further I was able to observe that the use of a
vma_iter_next_range() and vma_prev() pair, causing an unnecessary maple
tree walk.  In addition there is work that we do that is simply
unnecessary for brk().

Therefore, add a special VMA merge mode VMG_FLAG_JUST_EXPAND to avoid
doing any of this - it assumes the VMA iterator is pointing at the
previous VMA and which skips logic that brk() does not require.

This mostly eliminates the performance regression reducing it to ~2% which
is in the realm of noise.  In addition, the will-it-scale test brk2,
written to be more representative of real-world brk() usage, shows a
modest performance improvement - which gives me confidence that we are not
meaningfully regressing real workloads here.

This series includes a test asserting that the 'just expand' mode works as
expected.

With many thanks to Oliver Sang for helping with performance testing of
candidate patch sets!

[0]:https://lore.kernel.org/linux-mm/202409301043.629bea78-oliver.sang@intel.com


This patch (of 2):

We know in advance that do_brk_flags() wants only to perform a VMA
expansion (if the prior VMA is compatible), and that we assume no
mergeable VMA follows it.

These are the semantics of this function prior to the recent rewrite of
the VMA merging logic, however we are now doing more work than necessary -
positioning the VMA iterator at the prior VMA and performing tasks that
are not required.

Add a new field to the vmg struct to permit merge flags and add a new
merge flag VMG_FLAG_JUST_EXPAND which implies this behaviour, and have
do_brk_flags() use this.

This fixes a reported performance regression in a brk() benchmarking suite.

Link: https://lkml.kernel.org/r/cover.1729174352.git.lorenzo.stoakes@oracle.com
Link: https://lkml.kernel.org/r/4e65d4395e5841c5acf8470dbcb714016364fd39.1729174352.git.lorenzo.stoakes@oracle.com
Fixes: cacded5e42 ("mm: avoid using vma_merge() for new VMAs")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/linux-mm/202409301043.629bea78-oliver.sang@intel.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Jann Horn <jannh@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-10-28 21:40:40 -07:00
..
damon mm/damon/tests/sysfs-kunit.h: fix memory leak in damon_sysfs_test_add_targets() 2024-10-17 00:28:08 -07:00
kasan LoongArch: Set initial pte entry with PAGE_GLOBAL for kernel space 2024-10-21 22:11:19 +08:00
kfence mm: kfence: fix elapsed time for allocated/freed track 2024-09-26 14:01:44 -07:00
kmsan kmsan: do not pass NULL pointers as 0 2024-07-03 19:30:26 -07:00
backing-dev.c writeback: support retrieving per group debug writeback stats of bdi 2024-05-05 17:53:51 -07:00
balloon_compaction.c mm: remove MIGRATE_SYNC_NO_COPY mode 2024-07-03 19:30:00 -07:00
bootmem_info.c bootmem: use kmemleak_free_part_phys in put_page_bootmem 2023-10-25 16:47:13 -07:00
cma_debug.c
cma_sysfs.c mm/cma: add sysfs file 'release_pages_success' 2024-02-22 10:24:57 -08:00
cma.c mm/cma: add cma_{alloc,free}_folio() 2024-09-03 21:15:36 -07:00
cma.h mm/cma: add sysfs file 'release_pages_success' 2024-02-22 10:24:57 -08:00
compaction.c mm:page_alloc: fix the NULL ac->nodemask in __alloc_pages_slowpath() 2024-09-03 21:15:47 -07:00
debug_page_alloc.c mm: page_alloc: consolidate free page accounting 2024-04-25 20:56:04 -07:00
debug_page_ref.c
debug_vm_pgtable.c mm/debug_vm_pgtable: Use pxdp_get() for accessing page table entries 2024-09-17 01:07:01 -07:00
debug.c mm: support only one page_type per page 2024-09-03 21:15:43 -07:00
dmapool_test.c mm/dmapool: add MODULE_DESCRIPTION() 2024-07-03 19:29:58 -07:00
dmapool.c mm/mempool/dmapool: remove CONFIG_DEBUG_SLAB ifdefs 2023-12-05 11:17:58 +01:00
early_ioremap.c mm/early_ioremap.c: improve the execution efficiency of early_ioremap_setup() 2023-06-09 16:25:56 -07:00
execmem.c mm/execmem, arch: convert remaining overrides of module_alloc to execmem 2024-05-14 00:31:43 -07:00
fadvise.c introduce fd_file(), convert all accessors to it. 2024-08-12 22:00:43 -04:00
fail_page_alloc.c fault-inject: improve build for CONFIG_FAULT_INJECTION=n 2024-09-01 20:43:33 -07:00
failslab.c fault-inject: improve build for CONFIG_FAULT_INJECTION=n 2024-09-01 20:43:33 -07:00
filemap.c mm/filemap: fix filemap_get_folios_contig THP panic 2024-09-26 14:01:43 -07:00
folio-compat.c mm: remove putback_lru_page() 2024-09-09 16:38:59 -07:00
gup_test.c Merge mm-hotfixes-stable into mm-stable to pick up depended-upon changes. 2023-06-23 16:58:19 -07:00
gup_test.h mm/gup_test: start/stop/read functionality for PIN LONGTERM test 2022-11-08 17:37:15 -08:00
gup.c mm/hugetlb: simplify refs in memfd_alloc_folio 2024-09-26 14:01:44 -07:00
highmem.c mm/highmem: make nr_free_highpages() return "unsigned long" 2024-07-03 19:30:06 -07:00
hmm.c mm: provide mm_struct and address to huge_ptep_get() 2024-07-12 15:52:15 -07:00
huge_memory.c mm: huge_memory: add vma_thp_disabled() and thp_disabled_by_hw() 2024-10-17 00:28:10 -07:00
hugetlb_cgroup.c mm: memcg: don't call propagate_protected_usage() needlessly 2024-09-01 20:25:50 -07:00
hugetlb_vmemmap.c mm/hugetlb_vmemmap: don't synchronize_rcu() without HVO 2024-09-01 20:25:45 -07:00
hugetlb_vmemmap.h mm: hugetlb_vmemmap: fix reference to nonexistent file 2023-10-25 16:47:14 -07:00
hugetlb.c mm/hugetlb: fix memfd_pin_folios resv_huge_pages leak 2024-09-26 14:01:43 -07:00
hwpoison-inject.c mm/hwpoison: add MODULE_DESCRIPTION() 2024-07-03 19:29:58 -07:00
init-mm.c mm: Deprecate pasid field 2023-12-12 10:11:32 +01:00
internal.h ALong with the usual shower of singleton patches, notable patch series in 2024-09-21 07:29:05 -07:00
interval_tree.c
io-mapping.c
ioremap.c mm: ioremap: remove unneeded ioremap_allowed and iounmap_allowed 2023-08-18 10:12:36 -07:00
Kconfig resource: remove dependency on SPARSEMEM from GET_FREE_REGION 2024-10-28 21:40:39 -07:00
Kconfig.debug slub: Introduce CONFIG_SLUB_RCU_DEBUG 2024-08-27 14:12:51 +02:00
khugepaged.c mm: khugepaged: fix the incorrect statistics when collapsing large file folios 2024-10-17 00:28:10 -07:00
kmemleak.c mm/kmemleak: use IS_ERR_PCPU() for pointer in the percpu address space 2024-09-03 21:15:38 -07:00
ksm.c mm: remove PageSwapCache 2024-09-03 21:15:44 -07:00
list_lru.c mm: list_lru: fix UAF for memory cgroup 2024-08-07 18:33:56 -07:00
maccess.c mm: Fix copy_from_user_nofault(). 2023-04-12 17:36:23 -07:00
madvise.c ALong with the usual shower of singleton patches, notable patch series in 2024-09-21 07:29:05 -07:00
Makefile mm: introduce numa_emulation 2024-09-03 21:15:31 -07:00
mapping_dirty_helpers.c mm: fix clean_record_shared_mapping_range kernel-doc 2023-08-24 16:20:30 -07:00
memblock.c memblock: updates for 6.12-rc1 2024-09-25 11:35:19 -07:00
memcontrol-v1.c struct fd layout change (and conversion to accessor helpers) 2024-09-23 09:35:36 -07:00
memcontrol-v1.h memcg: cleanup with !CONFIG_MEMCG_V1 2024-09-17 01:07:00 -07:00
memcontrol.c ALong with the usual shower of singleton patches, notable patch series in 2024-09-21 07:29:05 -07:00
memfd.c mm/hugetlb: simplify refs in memfd_alloc_folio 2024-09-26 14:01:44 -07:00
memory_hotplug.c ALong with the usual shower of singleton patches, notable patch series in 2024-09-21 07:29:05 -07:00
memory-failure.c mm: migrate: add isolate_folio_to_list() 2024-09-03 21:15:59 -07:00
memory-tiers.c memory tiers: use default_dram_perf_ref_source in log message 2024-09-26 14:01:44 -07:00
memory.c mm: fix follow_pfnmap API lockdep assert 2024-10-18 09:50:05 -07:00
mempolicy.c mm,memcg: provide per-cgroup counters for NUMA balancing operations 2024-09-03 21:15:36 -07:00
mempool.c mm: fix xyz_noprof functions calling profiled functions 2024-06-05 19:19:26 -07:00
memremap.c mm: convert put_devmap_managed_page_refs() to put_devmap_managed_folio_refs() 2024-05-05 17:53:49 -07:00
memtest.c memtest: use {READ,WRITE}_ONCE in memory scanning 2024-03-13 12:12:21 -07:00
migrate_device.c mm: remap unused subpages to shared zeropage when splitting isolated thp 2024-09-09 16:39:03 -07:00
migrate.c mm: migrate: annotate data-race in migrate_folio_unmap() 2024-09-26 14:01:44 -07:00
mincore.c mm: provide mm_struct and address to huge_ptep_get() 2024-07-12 15:52:15 -07:00
mlock.c Random number generator updates for Linux 6.11-rc1. 2024-07-24 10:29:50 -07:00
mm_init.c mm: drop CONFIG_HAVE_ARCH_NODEDATA_EXTENSION 2024-09-03 21:15:28 -07:00
mm_slot.h mm: introduce common struct mm_slot 2022-10-03 14:02:43 -07:00
mmap_lock.c mm: mmap_lock: replace get_memcg_path_buf() with on-stack buffer 2024-07-03 19:30:26 -07:00
mmap.c mm/vma: add expand-only VMA merge mode and optimise do_brk_flags() 2024-10-28 21:40:40 -07:00
mmu_gather.c mm/mmu_gather: improve cond_resched() handling with large folios and expensive page freeing 2024-02-22 15:27:17 -08:00
mmu_notifier.c mm: move internal core VMA manipulation functions to own file 2024-09-01 20:25:54 -07:00
mmzone.c mm: improve code consistency with zonelist_* helper functions 2024-09-01 20:25:55 -07:00
mprotect.c mm/mprotect: replace can_modify_mm with can_modify_vma 2024-09-03 21:15:41 -07:00
mremap.c mm/mremap: fix move_normal_pmd/retract_page_tables race 2024-10-17 00:28:07 -07:00
mseal.c ALong with the usual shower of singleton patches, notable patch series in 2024-09-21 07:29:05 -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: remove follow_page() 2024-09-01 20:26:01 -07:00
numa_emulation.c mm: introduce numa_emulation 2024-09-03 21:15:31 -07:00
numa_memblks.c mm: numa_clear_kernel_node_hotplug: Add NUMA_NO_NODE check for node id 2024-10-28 21:40:40 -07:00
numa.c mm: make range-to-target_node lookup facility a part of numa_memblks 2024-09-03 21:15:32 -07:00
oom_kill.c memory: remove the now superfluous sentinel element from ctl_table array 2024-04-25 20:56:32 -07:00
page_alloc.c mm/page_alloc: let GFP_ATOMIC order-0 allocs access highatomic reserves 2024-10-28 21:40:39 -07:00
page_counter.c mm, memcg: cg2 memory{.swap,}.peak write handlers 2024-09-01 20:25:53 -07:00
page_ext.c mm: don't account memmap per-node 2024-08-15 22:16:14 -07:00
page_idle.c mm: page_idle: convert page idle to use a folio 2023-01-18 17:12:52 -08:00
page_io.c mm: fix swap_read_folio_zeromap() for large folios with partial zeromap 2024-09-17 01:07:01 -07:00
page_isolation.c mm: remove migration for HugePage in isolate_single_pageblock() 2024-09-03 21:15:40 -07:00
page_owner.c mm/page-owner: use gfp_nested_mask() instead of open coded masking 2024-05-19 14:40:44 -07:00
page_poison.c mm/page_poison: replace kmap_atomic() with kmap_local_page() 2023-12-10 16:51:50 -08:00
page_reporting.c mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER 2024-01-08 15:27:15 -08:00
page_reporting.h
page_table_check.c mm/page_table_check: fix crash on ZONE_DEVICE 2024-06-15 10:43:04 -07:00
page_vma_mapped.c mm: make page_mapped_in_vma conditional on CONFIG_MEMORY_FAILURE 2024-05-05 17:53:45 -07:00
page-writeback.c ALong with the usual shower of singleton patches, notable patch series in 2024-09-21 07:29:05 -07:00
pagewalk.c mm/pagewalk: fix usage of pmd_leaf()/pud_leaf() without present check 2024-10-28 21:40:38 -07:00
percpu-internal.h mm: remove CONFIG_MEMCG_KMEM 2024-07-10 12:14:54 -07:00
percpu-km.c
percpu-stats.c
percpu-vm.c percpu: clean up all mappings when pcpu_map_pages() fails 2024-04-25 20:55:49 -07:00
percpu.c percpu: remove pcpu_alloc_size() 2024-09-01 20:26:04 -07:00
pgalloc-track.h
pgtable-generic.c mm: fix race between __split_huge_pmd_locked() and GUP-fast 2024-05-07 10:37:00 -07:00
process_vm_access.c mm: fix process_vm_rw page counts 2023-12-10 16:51:39 -08:00
ptdump.c mm: ptdump: add check_wx_pages debugfs attribute 2024-02-22 10:24:47 -08:00
readahead.c struct fd layout change (and conversion to accessor helpers) 2024-09-23 09:35:36 -07:00
rmap.c mm: introduce a pageflag for partially mapped folios 2024-09-09 16:39:04 -07:00
rodata_test.c mm/rodata_test: use PAGE_ALIGNED() helper 2022-10-03 14:03:05 -07:00
secretmem.c secretmem: disable memfd_secret() if arch cannot set direct map 2024-10-09 12:47:19 -07:00
shmem_quota.c shmem_quota: build the object file conditionally to the config option 2024-09-01 20:25:45 -07:00
shmem.c mm: shmem: fix data-race in shmem_getattr() 2024-10-28 21:40:39 -07:00
show_mem.c mm/show_mem.c: report alloc tags in human readable units 2024-09-17 01:07:00 -07:00
shrinker_debug.c mm: shrinker: use min() to improve shrinker_debugfs_scan_write() 2024-09-03 21:15:40 -07:00
shrinker.c mm: shrinker: use kvzalloc_node() from expand_one_shrinker_info() 2024-01-05 09:58:32 -08:00
shuffle.c mm/shuffle: convert module_param_call to module_param_cb 2022-10-03 14:03:07 -07:00
shuffle.h mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER 2024-01-08 15:27:15 -08:00
slab_common.c mm, slab: suppress warnings in test_leak_destroy kunit test 2024-10-02 16:28:46 +02:00
slab.h mm, slab: suppress warnings in test_leak_destroy kunit test 2024-10-02 16:28:46 +02:00
slub.c mm, slab: suppress warnings in test_leak_destroy kunit test 2024-10-02 16:28:46 +02:00
sparse-vmemmap.c LoongArch: Set initial pte entry with PAGE_GLOBAL for kernel space 2024-10-21 22:11:19 +08:00
sparse.c A set of X86 fixes: 2024-09-01 14:43:08 -07:00
swap_cgroup.c mm: attempt to batch free swap entries for zap_pte_range() 2024-09-03 21:15:33 -07:00
swap_slots.c mm: swap: update get_swap_pages() to take folio order 2024-04-25 20:56:37 -07:00
swap_state.c mm: add nr argument in mem_cgroup_swapin_uncharge_swap() helper to support large folios 2024-09-17 01:07:01 -07:00
swap.c mm: remove isolate_lru_page() 2024-09-09 16:38:59 -07:00
swap.h mm: fix swap_read_folio_zeromap() for large folios with partial zeromap 2024-09-17 01:07:01 -07:00
swapfile.c mm/swapfile: skip HugeTLB pages for unuse_vma 2024-10-17 00:28:11 -07:00
truncate.c mm: Fix missing folio invalidation calls during truncation 2024-08-24 16:09:16 +02:00
usercopy.c mm: Fix copy_from_user_nofault(). 2023-04-12 17:36:23 -07:00
userfaultfd.c ALong with the usual shower of singleton patches, notable patch series in 2024-09-21 07:29:05 -07:00
util.c mm: only enforce minimum stack gap size if it's sensible 2024-09-01 20:26:02 -07:00
vma_internal.h mm: remove duplicated include in vma_internal.h 2024-09-01 20:26:02 -07:00
vma.c mm/vma: add expand-only VMA merge mode and optimise do_brk_flags() 2024-10-28 21:40:40 -07:00
vma.h mm/vma: add expand-only VMA merge mode and optimise do_brk_flags() 2024-10-28 21:40:40 -07:00
vmalloc.c ALong with the usual shower of singleton patches, notable patch series in 2024-09-21 07:29:05 -07:00
vmpressure.c eventfd: simplify eventfd_signal() 2023-11-28 14:08:38 +01:00
vmscan.c mm/mglru: only clear kswapd_failures if reclaimable 2024-10-17 00:28:12 -07:00
vmstat.c mm: split underused THPs 2024-09-09 16:39:04 -07:00
workingset.c cachestat: do not flush stats in recency check 2024-07-03 22:40:37 -07:00
z3fold.c mm/z3fold: add __percpu annotation to *unbuddied pointer in struct z3fold_pool 2024-09-01 20:25:56 -07:00
zbud.c mm: zpool: return pool size in pages 2024-04-25 20:55:48 -07:00
zpool.c mm: zpool: return pool size in pages 2024-04-25 20:55:48 -07:00
zsmalloc.c ALong with the usual shower of singleton patches, notable patch series in 2024-09-21 07:29:05 -07:00
zswap.c mm: zswap: delete comments for "value" member of 'struct zswap_entry'. 2024-10-09 12:47:19 -07:00