linux/mm
Kemeng Shi fabd2e42bc mm: correct calculation of wb's bg_thresh in cgroup domain
wb_calc_thresh() is calculating wb's share of bg_thresh in the global
domain.  However in case of cgroup writeback this is not the right
thing to do.  Consider the following domain hierarchy:

                global domain (> 20G)
                /                 \
          cgroup1 (10G)     cgroup2 (10G)
                |                 |
bdi            wb1               wb2

and assume wb1 and wb2 have the same bandwidth and the background
threshold is set at 10%.  The bg_thresh of cgroup1 and cgroup2 is going
to be 1G.  Now because wb_calc_thresh(mdtc->wb, mdtc->bg_thresh)
calculates per-wb threshold in the global domain as (wb bandwidth) /
(domain bandwidth) it returns bg_thresh for wb1 as 0.5G although it has
nobody to compete against in cgroup1.

Fix the problem by calculating wb's share of bg_thresh in the cgroup
domain.

Test as following:
/* make it easier to observe the issue */
echo 300000 > /proc/sys/vm/dirty_expire_centisecs
echo 100 > /proc/sys/vm/dirty_writeback_centisecs

/* run fio in wb1 */
cd /sys/fs/cgroup
echo "+memory +io" > cgroup.subtree_control
mkdir group1
cd group1
echo 10G > memory.high
echo 10G > memory.max
echo $$ > cgroup.procs
mkfs.ext4 -F /dev/vdb
mount /dev/vdb /bdi1/
fio -name test -filename=/bdi1/file -size=600M -ioengine=libaio -bs=4K \
-iodepth=1 -rw=write -direct=0 --time_based -runtime=600 -invalidate=0

/* run fio in wb2 with a new shell */
cd /sys/fs/cgroup
mkdir group2
cd group2
echo 10G > memory.high
echo 10G > memory.max
echo $$ > cgroup.procs
mkfs.ext4 -F /dev/vdc
mount /dev/vdc /bdi2/
fio -name test -filename=/bdi2/file -size=600M -ioengine=libaio -bs=4K \
-iodepth=1 -rw=write -direct=0 --time_based -runtime=600 -invalidate=0

Before fix, the wrttien pages of wb1 and wb2 reported from
toos/writeback/wb_monitor.py keep growing. After fix, rare written pages
are accumulated.
There is no obvious change in fio result.

[jack@suse.cz: changelog rewording]
Link: https://lkml.kernel.org/r/20240425131724.36778-3-shikemeng@huaweicloud.com
Fixes: 74d3694433 ("writeback: Fix performance regression in wb_over_bg_thresh()")
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Howard Cochran <hcochran@kernelspring.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-05-05 17:53:52 -07:00
..
damon mm: madvise: pageout: ignore references rather than clearing young 2024-03-04 17:01:18 -08:00
kasan fix missing vmalloc.h includes 2024-04-25 20:55:49 -07:00
kfence mm: introduce slabobj_ext to support slab object extensions 2024-04-25 20:55:51 -07:00
kmsan mm: kmsan: remove runtime checks from kmsan_unpoison_memory() 2024-02-22 10:24:41 -08:00
backing-dev.c writeback: support retrieving per group debug writeback stats of bdi 2024-05-05 17:53:51 -07:00
balloon_compaction.c
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: drop incorrect alignment check in cma_init_reserved_mem 2024-04-25 20:56:42 -07:00
cma.h mm/cma: add sysfs file 'release_pages_success' 2024-02-22 10:24:57 -08:00
compaction.c memory: remove the now superfluous sentinel element from ctl_table array 2024-04-25 20:56:32 -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 fix missing vmalloc.h includes 2024-04-25 20:55:49 -07:00
debug.c mm/debug: print only page mapcount (excluding folio entire mapcount) in __dump_folio() 2024-05-05 17:53:31 -07:00
dmapool_test.c
dmapool.c mm/mempool/dmapool: remove CONFIG_DEBUG_SLAB ifdefs 2023-12-05 11:17:58 +01:00
early_ioremap.c
fadvise.c
fail_page_alloc.c
failslab.c
filemap.c mm: filemap: batch mm counter updating in filemap_map_pages() 2024-05-05 17:53:36 -07:00
folio-compat.c mm: remove __set_page_dirty_nobuffers() 2024-04-25 20:56:25 -07:00
gup_test.c
gup_test.h
gup.c gup: use folios for gup_devmap 2024-05-05 17:53:49 -07:00
highmem.c x86/kexec: use pr_err() instead of kexec_dprintk() when an error occurs 2023-12-29 12:22:28 -08:00
hmm.c mm/treewide: replace pXd_huge() with pXd_leaf() 2024-04-25 20:55:46 -07:00
huge_memory.c mm/huge_memory: improve split_huge_page_to_list_to_order() return value documentation 2024-05-05 17:53:42 -07:00
hugetlb_cgroup.c mm/hugetlb: assert hugetlb_lock in __hugetlb_cgroup_commit_charge 2024-05-05 17:53:41 -07:00
hugetlb_vmemmap.c memory: remove the now superfluous sentinel element from ctl_table array 2024-04-25 20:56:32 -07:00
hugetlb_vmemmap.h mm: hugetlb_vmemmap: fix reference to nonexistent file 2023-10-25 16:47:14 -07:00
hugetlb.c mm: convert hugetlb_page_mapping_lock_write to folio 2024-05-05 17:53:46 -07:00
hwpoison-inject.c mm/memory-failure: convert shake_page() to shake_folio() 2024-05-05 17:53:45 -07:00
init-mm.c mm: Deprecate pasid field 2023-12-12 10:11:32 +01:00
internal.h mm/memory-failure: convert shake_page() to shake_folio() 2024-05-05 17:53:45 -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 mm/treewide: rename CONFIG_HAVE_FAST_GUP to CONFIG_HAVE_GUP_FAST 2024-04-25 20:56:41 -07:00
Kconfig.debug mm/slub: unify all sl[au]b parameters with "slab_$param" 2024-01-22 10:31:08 +01:00
khugepaged.c mm/khugepaged: replace page_mapcount() check by folio_likely_mapped_shared() 2024-05-05 17:53:50 -07:00
kmemleak.c mm/kmemleak: compact kmemleak_object further 2024-04-25 20:56:05 -07:00
ksm.c mm/memory-failure: pass the folio to collect_procs_ksm() 2024-05-05 17:53:47 -07:00
list_lru.c mm/zswap: stop lru list shrinking when encounter warm region 2024-02-22 10:24:54 -08:00
maccess.c
madvise.c mm/madvise: optimize lazyfreeing with mTHP in madvise_free 2024-05-05 17:53:43 -07:00
Makefile mm/kmemleak: disable KASAN instrumentation in kmemleak 2024-04-25 20:56:05 -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 cxl fixes for 6.8-rc6 2024-02-24 15:53:40 -08:00
memcontrol.c memcg: fix data-race KCSAN bug in rstats 2024-05-05 17:53:50 -07:00
memfd.c mm/memfd: refactor memfd_tag_pins() and memfd_wait_for_pins() 2024-03-04 17:01:21 -08:00
memory_hotplug.c mm/hugetlb: rename dissolve_free_huge_pages() to dissolve_free_hugetlb_folios() 2024-05-05 17:53:35 -07:00
memory-failure.c memory-failure: remove calls to page_mapping() 2024-05-05 17:53:48 -07:00
memory-tiers.c memory tier: create CPUless memory tiers after obtaining HMAT info 2024-05-05 17:53:26 -07:00
memory.c mm: memory: check userfaultfd_wp() in vmf_orig_pte_uffd_wp() 2024-05-05 17:53:43 -07:00
mempolicy.c mm: add pmd_folio() 2024-04-25 20:56:19 -07:00
mempool.c mempool: hook up to memory allocation profiling 2024-04-25 20:55:56 -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 migrate: expand the use of folio in __migrate_device_pages() 2024-05-05 17:53:48 -07:00
migrate.c mm: convert hugetlb_page_mapping_lock_write to folio 2024-05-05 17:53:46 -07:00
mincore.c mm: enable page walking API to lock vmas during the walk 2023-08-21 13:07:20 -07:00
mlock.c mm: add pmd_folio() 2024-04-25 20:56:19 -07:00
mm_init.c mm: init_mlocked_on_free_v3 2024-04-25 20:56:29 -07:00
mm_slot.h
mmap_lock.c
mmap.c mm/mmap: make accountable_mapping return bool 2024-05-05 17:53:26 -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 mmu_notifiers: rename invalidate_range notifier 2023-08-18 10:12:41 -07:00
mmzone.c zswap: shrink zswap pool based on memory pressure 2023-12-12 10:57:02 -08:00
mprotect.c mm: support multi-size THP numa balancing 2024-04-25 20:56:30 -07:00
mremap.c mm: remove "prot" parameter from move_pte() 2024-04-25 20:56:24 -07:00
msync.c
nommu.c mm: remove follow_pfn 2024-04-25 20:56:12 -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: allowing mTHP compaction to capture the freed page directly 2024-05-05 17:53:37 -07:00
page_counter.c
page_ext.c mm: make page_ext_get() take a const argument 2024-04-25 20:56:14 -07:00
page_idle.c
page_io.c mm: add per-order mTHP anon_swpout and anon_swpout_fallback counters 2024-05-05 17:53:35 -07:00
page_isolation.c mm: page_isolation: prepare for hygienic freelists 2024-04-25 20:56:04 -07:00
page_owner.c mm: introduce slabobj_ext to support slab object extensions 2024-04-25 20:55:51 -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: support userfault wr-protect entries 2024-05-05 17:53:41 -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 mm: correct calculation of wb's bg_thresh in cgroup domain 2024-05-05 17:53:52 -07:00
pagewalk.c mm: pagewalk: assert write mmap lock only for walking the user page tables 2023-12-10 16:51:53 -08:00
percpu-internal.h mm: percpu: add codetag reference into pcpuobj_ext 2024-04-25 20:55:56 -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 mm: percpu: enable per-cpu allocation tagging 2024-04-25 20:55:56 -07:00
pgalloc-track.h
pgtable-generic.c mm/pgtable: notes on pte_offset_map[_lock]() 2023-08-18 10:12:25 -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 mm/readahead: break read-ahead loop if filemap_add_folio return -ENOMEM 2024-04-25 20:56:07 -07:00
rmap.c mm: track mapcount of large folios in single value 2024-05-05 17:53:28 -07:00
rodata_test.c
secretmem.c mm/secretmem: use a folio in secretmem_fault() 2023-08-21 13:38:02 -07:00
shmem_quota.c tmpfs: fix race on handling dquot rbtree 2024-03-26 11:07:23 -07:00
shmem.c mm: switch mm->get_unmapped_area() to a flag 2024-04-25 20:56:25 -07:00
show_mem.c lib: add memory allocations report in show_mem() 2024-04-25 20:55:57 -07:00
shrinker_debug.c mm: shrinker: convert shrinker_rwsem to mutex 2023-10-04 10:32:26 -07:00
shrinker.c mm: shrinker: use kvzalloc_node() from expand_one_shrinker_info() 2024-01-05 09:58:32 -08:00
shuffle.c
shuffle.h mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER 2024-01-08 15:27:15 -08:00
slab_common.c mm/slab: enable slab allocation tagging for kmalloc and friends 2024-04-25 20:55:55 -07:00
slab.h memcg: simple cleanup of stats update functions 2024-05-05 17:53:44 -07:00
slub.c mm, slab: move slab_memcg hooks to mm/memcontrol.c 2024-04-25 20:56:16 -07:00
sparse-vmemmap.c mm/vmemmap: allow architectures to override how vmemmap optimization works 2023-08-18 10:12:53 -07:00
sparse.c mm/sparse: guard the size of mem_section is power of 2 2024-05-05 17:53:40 -07:00
swap_cgroup.c
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: remove struct page from get_shadow_from_swap_cache 2024-04-25 20:56:40 -07:00
swap.c mm: add kernel-doc for folio_mark_accessed() 2024-05-05 17:53:50 -07:00
swap.h mm/swap: fix race when skipping swapcache 2024-02-20 14:20:48 -08:00
swapfile.c mm: swapfile: check usable swap device in __folio_throttle_swaprate() 2024-05-05 17:53:42 -07:00
truncate.c mm: convert pagecache_isize_extended to use a folio 2024-04-25 20:56:43 -07:00
usercopy.c
userfaultfd.c userfault; expand folio use in mfill_atomic_install_pte() 2024-05-05 17:53:48 -07:00
util.c mm: switch mm->get_unmapped_area() to a flag 2024-04-25 20:56:25 -07:00
vmalloc.c mm: vmalloc: dump page owner info if page is already mapped 2024-05-05 17:53:51 -07:00
vmpressure.c eventfd: simplify eventfd_signal() 2023-11-28 14:08:38 +01:00
vmscan.c mm: add per-order mTHP anon_swpout and anon_swpout_fallback counters 2024-05-05 17:53:35 -07:00
vmstat.c mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER 2024-01-08 15:27:15 -08:00
workingset.c mm: move mapping_set_update out of <linux/swap.h> 2024-02-21 11:36:50 +05:30
z3fold.c mm: zpool: return pool size in pages 2024-04-25 20:55:48 -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 mm: zpool: return pool size in pages 2024-04-25 20:55:48 -07:00
zswap.c mm: zswap: remove same_filled module params 2024-05-05 17:53:38 -07:00