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91cdcd8d62
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Johannes Weiner 91cdcd8d62 mm: zswap: optimize zswap pool size tracking 
Profiling the munmap() of a zswapped memory region shows 60% of the total
cycles currently going into updating the zswap_pool_total_size.

There are three consumers of this counter:
- store, to enforce the globally configured pool limit
- meminfo & debugfs, to report the size to the user
- shrink, to determine the batch size for each cycle

Instead of aggregating everytime an entry enters or exits the zswap
pool, aggregate the value from the zpools on-demand:

- Stores aggregate the counter anyway upon success. Aggregating to
  check the limit instead is the same amount of work.

- Meminfo & debugfs might benefit somewhat from a pre-aggregated
  counter, but aren't exactly hotpaths.

- Shrinking can aggregate once for every cycle instead of doing it for
  every freed entry. As the shrinker might work on tens or hundreds of
  objects per scan cycle, this is a large reduction in aggregations.

The paths that benefit dramatically are swapin, swapoff, and unmaps. 
There could be millions of pages being processed until somebody asks for
the pool size again.  This eliminates the pool size updates from those
paths entirely.

Top profile entries for a 24G range munmap(), before:

    38.54%  zswap-unmap  [kernel.kallsyms]  [k] zs_zpool_total_size
    12.51%  zswap-unmap  [kernel.kallsyms]  [k] zpool_get_total_size
     9.10%  zswap-unmap  [kernel.kallsyms]  [k] zswap_update_total_size
     2.95%  zswap-unmap  [kernel.kallsyms]  [k] obj_cgroup_uncharge_zswap
     2.88%  zswap-unmap  [kernel.kallsyms]  [k] __slab_free
     2.86%  zswap-unmap  [kernel.kallsyms]  [k] xas_store

and after:

     7.70%  zswap-unmap  [kernel.kallsyms]  [k] __slab_free
     7.16%  zswap-unmap  [kernel.kallsyms]  [k] obj_cgroup_uncharge_zswap
     6.74%  zswap-unmap  [kernel.kallsyms]  [k] xas_store

It was also briefly considered to move to a single atomic in zswap
that is updated by the backends, since zswap only cares about the sum
of all pools anyway. However, zram directly needs per-pool information
out of zsmalloc. To keep the backend from having to update two atomics
every time, I opted for the lazy aggregation instead for now.

Link: https://lkml.kernel.org/r/20240312153901.3441-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-04-25 20:55:47 -07:00
..
damon mm: madvise: pageout: ignore references rather than clearing young 2024-03-04 17:01:18 -08:00
kasan - Sumanth Korikkar has taught s390 to allocate hotplug-time page frames 2024-03-14 17:43:30 -07:00
kfence KFENCE: cleanup kfence_guarded_alloc() after CONFIG_SLAB removal 2023-12-05 11:17:58 +01:00
kmsan mm: kmsan: remove runtime checks from kmsan_unpoison_memory() 2024-02-22 10:24:41 -08:00
backing-dev.c vfs-6.9.misc 2024-03-11 09:38:17 -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: add sysfs file 'release_pages_success' 2024-02-22 10:24:57 -08:00
cma.h mm/cma: add sysfs file 'release_pages_success' 2024-02-22 10:24:57 -08:00
compaction.c - Sumanth Korikkar has taught s390 to allocate hotplug-time page frames 2024-03-14 17:43:30 -07:00
debug_page_alloc.c mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER 2024-01-08 15:27:15 -08:00
debug_page_ref.c
debug_vm_pgtable.c mm/debug_vm_pgtable: fix BUG_ON with pud advanced test 2024-02-23 17:27:13 -08:00
debug.c mm: make dump_page() take a const argument 2024-03-06 13:04:18 -08:00
dmapool_test.c dmapool: add alloc/free performance test 2023-04-05 19:42:38 -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
fadvise.c mm: remove unnecessary pagevec includes 2023-06-23 16:59:31 -07:00
fail_page_alloc.c mm: page_alloc: split out FAIL_PAGE_ALLOC 2023-06-09 16:25:23 -07:00
failslab.c mm: fix unexpected changes to {failslab|fail_page_alloc}.attr 2022-11-22 18:50:44 -08:00
filemap.c mm: cachestat: fix two shmem bugs 2024-03-26 11:07:20 -07:00
folio-compat.c mm: remove page_add_new_anon_rmap and lru_cache_add_inactive_or_unevictable 2023-12-29 11:58:27 -08:00
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/treewide: replace pXd_huge() with pXd_leaf() 2024-04-25 20:55:46 -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 userfaultfd: change src_folio after ensuring it's unpinned in UFFDIO_MOVE 2024-04-16 15:39:48 -07:00
hugetlb_cgroup.c mm, hugetlb: remove HUGETLB_CGROUP_MIN_ORDER 2023-10-18 14:34:17 -07:00
hugetlb_vmemmap.c mm: hugetlb_vmemmap: move mmap lock to vmemmap_remap_range() 2023-12-12 10:57:08 -08:00
hugetlb_vmemmap.h mm: hugetlb_vmemmap: fix reference to nonexistent file 2023-10-25 16:47:14 -07:00
hugetlb.c mm/hugetlb: fix DEBUG_LOCKS_WARN_ON(1) when dissolve_free_hugetlb_folio() 2024-04-25 10:07:27 -07:00
hwpoison-inject.c
init-mm.c mm: Deprecate pasid field 2023-12-12 10:11:32 +01:00
internal.h mm/madvise: make MADV_POPULATE_(READ|WRITE) handle VM_FAULT_RETRY properly 2024-04-16 15:39:48 -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 Kbuild updates for v6.9 2024-03-21 14:41:00 -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: convert free_swap_cache() to take a folio 2024-03-04 17:01:26 -08:00
kmemleak.c kmemleak: avoid RCU stalls when freeing metadata for per-CPU pointers 2023-12-12 10:57:07 -08:00
ksm.c mm: convert page_try_share_anon_rmap() to folio_try_share_anon_rmap_[pte|pmd]() 2023-12-29 11:58:56 -08:00
list_lru.c mm/zswap: stop lru list shrinking when encounter warm region 2024-02-22 10:24:54 -08:00
maccess.c mm: Fix copy_from_user_nofault(). 2023-04-12 17:36:23 -07:00
madvise.c mm/madvise: don't perform madvise VMA walk for MADV_POPULATE_(READ|WRITE) 2024-04-25 20:55:43 -07:00
Makefile kbuild: make -Woverride-init warnings more consistent 2024-03-31 11:32:26 +09:00
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 mm: memcg: add NULL check to obj_cgroup_put() 2024-04-25 20:55:43 -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/memory_hotplug: export mhp_supports_memmap_on_memory() 2024-02-22 10:24:40 -08:00
memory-failure.c mm/memory-failure: fix deadlock when hugetlb_optimize_vmemmap is enabled 2024-04-16 15:39:50 -07:00
memory-tiers.c mm/demotion: print demotion targets 2024-02-22 10:24:55 -08:00
memory.c mm/treewide: replace pXd_huge() with pXd_leaf() 2024-04-25 20:55:46 -07:00
mempolicy.c mm/mempolicy: use a folio in do_mbind() 2024-03-06 13:04:18 -08:00
mempool.c mempool: kvmalloc pool 2024-03-13 18:38:13 -04:00
memremap.c mm: remove stale example from comment 2023-12-29 11:58:26 -08:00
memtest.c memtest: use {READ,WRITE}_ONCE in memory scanning 2024-03-13 12:12:21 -07:00
migrate_device.c mm: convert page_try_share_anon_rmap() to folio_try_share_anon_rmap_[pte|pmd]() 2023-12-29 11:58:56 -08:00
migrate.c merge mm-hotfixes-stable into mm-nonmm-stable to pick up stackdepot changes 2024-02-23 17:28:43 -08:00
mincore.c mm: enable page walking API to lock vmas during the walk 2023-08-21 13:07:20 -07:00
mlock.c mm: make folios_put() the basis of release_pages() 2024-03-04 17:01:22 -08:00
mm_init.c Author: Gang Li padata: dispatch works on 2024-03-06 13:04:17 -08:00
mm_slot.h
mmap_lock.c
mmap.c RISC-V Patches for the 6.9 Merge Window 2024-03-22 10:41:13 -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 mprotect: use pfn_swap_entry_folio 2024-02-21 16:00:03 -08:00
mremap.c mm: abstract VMA merge and extend into vma_merge_extend() helper 2023-10-18 14:34:18 -07:00
msync.c
nommu.c mm/vmalloc: remove vmap_area_list 2024-02-23 17:48:19 -08:00
oom_kill.c mm: update mark_victim tracepoints fields 2024-03-04 17:01:16 -08:00
page_alloc.c mm: page_alloc: control latency caused by zone PCP draining 2024-04-25 20:55:44 -07:00
page_counter.c
page_ext.c mm/page_ext: move functions around for minor cleanups to page_ext 2023-08-18 10:12:31 -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 zswap: memcontrol: implement zswap writeback disabling 2023-12-29 20:22:11 -08:00
page_isolation.c mm: add alloc_contig_migrate_range allocation statistics 2024-03-04 17:01:27 -08:00
page_owner.c mm,page_owner: defer enablement of static branch 2024-04-16 15:39:51 -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: convert page_table_check_pte_set() to page_table_check_ptes_set() 2023-08-24 16:20:18 -07:00
page_vma_mapped.c mm: thp: introduce multi-size THP sysfs interface 2023-12-20 14:48:12 -08:00
page-writeback.c writeback: remove a use of write_cache_pages() from do_writepages() 2024-02-23 17:48:38 -08:00
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 percpu-internal/pcpu_chunk: re-layout pcpu_chunk structure to reduce false sharing 2023-06-19 16:19:29 -07:00
percpu-km.c
percpu-stats.c
percpu-vm.c
percpu.c mm: Introduce flush_cache_vmap_early() 2023-12-14 00:23:17 -08:00
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: support order-1 folios in the page cache 2024-03-04 17:01:19 -08:00
rmap.c rmap: replace two calls to compound_order with folio_order 2024-02-22 15:27:20 -08:00
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/shmem: inline shmem_is_huge() for disabled transparent hugepages 2024-04-16 15:39:51 -07:00
show_mem.c mm, treewide: introduce NR_PAGE_ORDERS 2024-01-08 15:27:15 -08:00
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 - Kuan-Wei Chiu has developed the well-named series "lib min_heap: Min 2024-03-14 18:03:09 -07:00
slab.h Merge branch 'slab/for-6.9/slab-flag-cleanups' into slab/for-linus 2024-03-12 10:16:56 +01:00
slub.c Merge branch 'slab/for-6.9/slab-flag-cleanups' into slab/for-linus 2024-03-12 10:16:56 +01:00
sparse-vmemmap.c mm/vmemmap: allow architectures to override how vmemmap optimization works 2023-08-18 10:12:53 -07:00
sparse.c mm/memory_hotplug: introduce MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE notifiers 2024-02-21 16:00:01 -08:00
swap_cgroup.c
swap_slots.c mm/zswap: invalidate zswap entry when swap entry free 2024-02-22 10:24:54 -08:00
swap_state.c mm: convert free_swap_cache() to take a folio 2024-03-04 17:01:26 -08:00
swap.c mm: fix list corruption in put_pages_list 2024-03-12 13:07:16 -07:00
swap.h mm/swap: fix race when skipping swapcache 2024-02-20 14:20:48 -08:00
swapfile.c - Sumanth Korikkar has taught s390 to allocate hotplug-time page frames 2024-03-14 17:43:30 -07:00
truncate.c fs: convert error_remove_page to error_remove_folio 2023-12-10 16:51:42 -08:00
usercopy.c mm: Fix copy_from_user_nofault(). 2023-04-12 17:36:23 -07:00
userfaultfd.c userfaultfd: fix deadlock warning when locking src and dst VMAs 2024-03-26 11:07:23 -07:00
util.c - Sumanth Korikkar has taught s390 to allocate hotplug-time page frames 2024-03-14 17:43:30 -07:00
vmalloc.c mm: vmalloc: fix lockdep warning 2024-04-05 11:21:30 -07:00
vmpressure.c eventfd: simplify eventfd_signal() 2023-11-28 14:08:38 +01:00
vmscan.c - Sumanth Korikkar has taught s390 to allocate hotplug-time page frames 2024-03-14 17:43:30 -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/z3fold: fix the comment for __encode_handle() 2024-02-23 17:48:31 -08:00
zbud.c mm: zswap: remove shrink from zpool interface 2023-06-19 16:19:27 -07:00
zpool.c mm: zswap: remove shrink from zpool interface 2023-06-19 16:19:27 -07:00
zsmalloc.c mm/zsmalloc: don't need to reserve LSB in handle 2024-03-04 17:01:28 -08:00
zswap.c mm: zswap: optimize zswap pool size tracking 2024-04-25 20:55:47 -07:00