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Message-ID: <20250908121503.20960-1-zhongjinji@honor.com> Date: Mon, 8 Sep 2025 20:15:03 +0800 From: zhongjinji <zhongjinji@...or.com> To: <mhocko@...e.com> CC: <akpm@...ux-foundation.org>, <feng.han@...or.com>, <liam.howlett@...cle.com>, <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>, <liulu.liu@...or.com>, <lorenzo.stoakes@...cle.com>, <rientjes@...gle.com>, <shakeel.butt@...ux.dev>, <surenb@...gle.com>, <tglx@...utronix.de>, <zhongjinji@...or.com> Subject: Re: [PATCH v7 2/2] mm/oom_kill: The OOM reaper traverses the VMA Since the perf report is too complicated, let us summarize the key points from the report. Conclusion: Compared to the version without the patch, the total time reduced by exit_mmap plus reaper work is roughly equal to the reduction in total pte spinlock waiting time. With the patch applied, for certain functions, the reaper performs more times, such as folio_remove_rmap_ptes, but the time spent by exit_mmap on folio_remove_rmap_ptes decreases accordingly. Summary of measurements (ms): +---------------------------------------------------------------+ | Category | Applying patch | Without patch| +-------------------------------+---------------+--------------+ | Total running time | 132.6 | 167.1 | | (exit_mmap + reaper work) | 72.4 + 60.2 | 90.7 + 76.4 | +-------------------------------+---------------+--------------+ | Time waiting for pte spinlock | 1.0 | 33.1 | | (exit_mmap + reaper work) | 0.4 + 0.6 | 10.0 + 23.1 | +-------------------------------+---------------+--------------+ | folio_remove_rmap_ptes time | 42.0 | 41.3 | | (exit_mmap + reaper work) | 18.4 + 23.6 | 22.4 + 18.9 | +---------------------------------------------------------------+ Report without patch: Arch: arm64 Event: cpu-clock (type 1, config 0) Samples: 6355 Event count: 90781175 do_exit |--93.81%-- mmput | |--99.46%-- exit_mmap | | |--76.74%-- unmap_vmas | | | |--9.14%-- [hit in function] | | | |--34.25%-- tlb_flush_mmu | | | |--31.13%-- folio_remove_rmap_ptes | | | |--15.04%-- __pte_offset_map_lock | | | |--5.43%-- free_swap_and_cache_nr | | | |--1.80%-- _raw_spin_lock | | | |--1.19%-- folio_mark_accessed | | | |--0.84%-- __tlb_remove_folio_pages | | | |--0.37%-- mas_find | | | |--0.37%-- percpu_counter_add_batch | | | |--0.20%-- __mod_lruvec_page_state | | | |--0.13%-- f2fs_dirty_data_folio | | | |--0.04%-- __rcu_read_unlock | | | |--0.04%-- tlb_flush_rmaps | | | | folio_remove_rmap_ptes | | | --0.02%-- folio_mark_dirty | | |--12.72%-- free_pgtables | | | |--0.53%-- [hit in function] | | | |--35.81%-- unlink_file_vma | | | |--28.38%-- down_write | | | |--17.11%-- unlink_anon_vmas | | | |--5.70%-- anon_vma_interval_tree_remove | | | |--3.71%-- mas_find | | | |--3.18%-- up_write | | | |--2.25%-- free_pgd_range | | | |--1.19%-- vma_interval_tree_remove | | | |--1.06%-- kmem_cache_free | | |--2.65%-- folio_remove_rmap_ptes | | |--2.50%-- __vm_area_free | | | |--11.49%-- [hit in function] | | | |--81.08%-- kmem_cache_free | | | |--4.05%-- _raw_spin_unlock_irqrestore | | | --3.38%-- anon_vma_name_free | | |--1.03%-- folio_mark_accessed | | |--0.96%-- __tlb_remove_folio_pages | | |--0.54%-- mas_find | | |--0.46%-- tlb_finish_mmu | | | |--96.30%-- free_pages_and_swap_cache | | | | |--80.77%-- release_pages | | |--0.44%-- kmem_cache_free | | |--0.39%-- __pte_offset_map_lock | | |--0.30%-- task_work_add | | |--0.19%-- __rcu_read_unlock | | |--0.17%-- fput | | |--0.13%-- __mt_destroy | | | mt_destroy_walk | | |--0.10%-- down_write | | |--0.07%-- unlink_file_vma | | |--0.05%-- percpu_counter_add_batch | | |--0.02%-- free_swap_and_cache_nr | | |--0.02%-- flush_tlb_batched_pending | | |--0.02%-- uprobe_munmap | | |--0.02%-- _raw_spin_unlock | | |--0.02%-- unlink_anon_vmas | | --0.02%-- up_write | |--0.40%-- fput | |--0.10%-- mas_find | |--0.02%-- kgsl_gpumem_vm_close | --0.02%-- __vm_area_free |--5.19%-- task_work_run |--0.42%-- exit_files | put_files_struct |--0.35%-- exit_task_namespaces Children Self Command Symbol 90752605 0 #APM_light-weig do_exit 90752605 0 #APM_light-weig get_signal 85138600 0 #APM_light-weig __mmput 84681480 399980 #APM_light-weig exit_mmap 64982465 5942560 #APM_light-weig unmap_vmas 22598870 1599920 #APM_light-weig free_pages_and_swap_cache 22498875 3314120 #APM_light-weig folio_remove_rmap_ptes 10985165 1442785 #APM_light-weig _raw_spin_lock 10770890 57140 #APM_light-weig free_pgtables 10099495 399980 #APM_light-weig __pte_offset_map_lock 8199590 1285650 #APM_light-weig folios_put_refs 4756905 685680 #APM_light-weig free_unref_page_list 4714050 14285 #APM_light-weig task_work_run 4671195 199990 #APM_light-weig ____fput 4085510 214275 #APM_light-weig __fput 3914090 57140 #APM_light-weig unlink_file_vma 3542680 28570 #APM_light-weig free_swap_and_cache_nr 3214125 2114180 #APM_light-weig free_unref_folios 3142700 14285 #APM_light-weig swap_entry_range_free 2828430 2828430 #APM_light-weig kmem_cache_free 2714150 528545 #APM_light-weig zram_free_page 2528445 114280 #APM_light-weig zram_slot_free_notify Arch: arm64 Event: cpu-clock (type 1, config 0) Samples: 5353 Event count: 76467605 kthread |--99.57%-- oom_reaper | |--0.28%-- [hit in function] | |--73.58%-- unmap_page_range | | |--8.67%-- [hit in function] | | |--41.59%-- __pte_offset_map_lock | | |--29.47%-- folio_remove_rmap_ptes | | |--16.11%-- tlb_flush_mmu | | | free_pages_and_swap_cache | | | |--9.49%-- [hit in function] | | |--1.66%-- folio_mark_accessed | | |--0.74%-- free_swap_and_cache_nr | | |--0.69%-- __tlb_remove_folio_pages | | |--0.41%-- __mod_lruvec_page_state | | |--0.33%-- _raw_spin_lock | | |--0.28%-- percpu_counter_add_batch | | |--0.03%-- tlb_flush_mmu_tlbonly | | --0.03%-- __rcu_read_unlock | |--19.94%-- tlb_finish_mmu | | |--23.24%-- [hit in function] | | |--76.39%-- free_pages_and_swap_cache | | |--0.28%-- free_pages | | --0.09%-- release_pages | |--3.21%-- folio_remove_rmap_ptes | |--1.16%-- __tlb_remove_folio_pages | |--1.16%-- folio_mark_accessed | |--0.36%-- __pte_offset_map_lock | |--0.28%-- mas_find | --0.02%-- __rcu_read_unlock |--0.17%-- tlb_finish_mmu |--0.15%-- mas_find |--0.06%-- memset |--0.04%-- unmap_page_range --0.02%-- tlb_gather_mmu Children Self Command Symbol 76467605 0 unknown kthread 76139050 214275 unknown oom_reaper 56054340 4885470 unknown unmap_page_range 23570250 385695 unknown __pte_offset_map_lock 23341690 257130 unknown _raw_spin_lock 23113130 23113130 unknown queued_spin_lock_slowpath 20627540 1371360 unknown free_pages_and_swap_cache 19027620 614255 unknown release_pages 18956195 3399830 unknown folio_remove_rmap_ptes 15313520 3656960 unknown tlb_finish_mmu 11799410 11785125 unknown cgroup_rstat_updated 11285150 11256580 unknown _raw_spin_unlock_irqrestore 9028120 0 unknown tlb_flush_mmu 8613855 1342790 unknown folios_put_refs 5442585 485690 unknown free_unref_page_list 4299785 1614205 unknown free_unref_folios 3385545 1299935 unknown free_unref_page_commit Report with patch: Arch: arm64 Event: cpu-clock (type 1, config 0) Samples: 5075 Event count: 72496375 |--99.98%-- do_notify_resume | |--92.63%-- mmput | | __mmput | | |--99.57%-- exit_mmap | | | |--0.79%-- [hit in function] | | | |--76.43%-- unmap_vmas | | | | |--8.39%-- [hit in function] | | | | |--42.80%-- tlb_flush_mmu | | | | | free_pages_and_swap_cache | | | | |--34.08%-- folio_remove_rmap_ptes | | | | |--9.51%-- free_swap_and_cache_nr | | | | |--2.40%-- _raw_spin_lock | | | | |--0.75%-- __tlb_remove_folio_pages | | | | |--0.48%-- mas_find | | | | |--0.36%-- __pte_offset_map_lock | | | | |--0.34%-- percpu_counter_add_batch | | | | |--0.34%-- folio_mark_accessed | | | | |--0.20%-- __mod_lruvec_page_state | | | | |--0.17%-- f2fs_dirty_data_folio | | | | |--0.11%-- __rcu_read_unlock | | | | |--0.03%-- _raw_spin_unlock | | | | |--0.03%-- tlb_flush_rmaps | | | | --0.03%-- uprobe_munmap | | | |--14.19%-- free_pgtables | | | |--2.52%-- __vm_area_free | | | |--1.52%-- folio_remove_rmap_ptes | | | |--0.83%-- mas_find | | | |--0.81%-- __tlb_remove_folio_pages | | | |--0.77%-- folio_mark_accessed | | | |--0.41%-- kmem_cache_free | | | |--0.36%-- task_work_add | | | |--0.34%-- fput | | | |--0.32%-- __pte_offset_map_lock | | | |--0.15%-- __rcu_read_unlock | | | |--0.15%-- __mt_destroy | | | |--0.09%-- unlink_file_vma | | | |--0.06%-- down_write | | | |--0.04%-- lookup_swap_cgroup_id | | | |--0.04%-- uprobe_munmap | | | |--0.04%-- percpu_counter_add_batch | | | |--0.04%-- up_write | | | |--0.02%-- flush_tlb_batched_pending | | | |--0.02%-- _raw_spin_unlock | | | |--0.02%-- unlink_anon_vmas | | | --0.02%-- tlb_finish_mmu | | | free_unref_page | | |--0.38%-- fput | | --0.04%-- mas_find | |--6.21%-- task_work_run | |--0.47%-- exit_task_namespaces | |--0.16%-- ____fput | --0.04%-- mm_update_next_owner Children Self Command Symbol 72482090 0 #APM6-IO get_signal 67139500 0 #APM6-IO __mmput 67139500 0 #APM6-IO mmput 66853800 528545 #APM6-IO exit_mmap 51097445 4285500 #APM6-IO unmap_vmas 21870335 0 #APM6-IO tlb_flush_mmu 21870335 1371360 #APM6-IO free_pages_and_swap_cache 20384695 485690 #APM6-IO release_pages 18427650 1814195 #APM6-IO folio_remove_rmap_ptes 13799310 13785025 #APM6-IO cgroup_rstat_updated 12842215 12842215 #APM6-IO _raw_spin_unlock_irqrestore 9485240 14285 #APM6-IO free_pgtables 7785325 428550 #APM6-IO folios_put_refs 4899755 642825 #APM6-IO free_unref_page_list 4856900 42855 #APM6-IO free_swap_and_cache_nr 4499775 14285 #APM6-IO task_work_run 4385495 114280 #APM6-IO ____fput 3971230 714250 #APM6-IO zram_free_page 3899805 14285 #APM6-IO swap_entry_range_free 3785525 185705 #APM6-IO zram_slot_free_notify 399980 399980 #APM6-IO __pte_offset_map_lock Arch: arm64 Event: cpu-clock (type 1, config 0) Samples: 4221 Event count: 60296985 Children Self Command Pid Tid Shared Object Symbol kthread |--99.53%-- oom_reaper | |--0.17%-- [hit in function] | |--55.77%-- unmap_page_range | | |--20.49%-- [hit in function] | | |--58.30%-- folio_remove_rmap_ptes | | |--11.48%-- tlb_flush_mmu | | |--3.33%-- folio_mark_accessed | | |--2.65%-- __tlb_remove_folio_pages | | |--1.37%-- _raw_spin_lock | | |--0.68%-- __mod_lruvec_page_state | | |--0.51%-- __pte_offset_map_lock | | |--0.43%-- percpu_counter_add_batch | | |--0.30%-- __rcu_read_unlock | | |--0.13%-- free_swap_and_cache_nr | | |--0.09%-- tlb_flush_mmu_tlbonly | | --0.04%-- __rcu_read_lock | |--32.21%-- tlb_finish_mmu | | |--88.69%-- free_pages_and_swap_cache | |--6.93%-- folio_remove_rmap_ptes | |--1.90%-- __tlb_remove_folio_pages | |--1.55%-- folio_mark_accessed | |--0.69%-- __pte_offset_map_lock | |--0.45%-- mas_find_rev | | |--21.05%-- [hit in function] | | --78.95%-- mas_prev_slot | |--0.12%-- mas_prev_slot | |--0.10%-- free_pages_and_swap_cache | |--0.07%-- __rcu_read_unlock | |--0.02%-- percpu_counter_add_batch | --0.02%-- lookup_swap_cgroup_id |--0.12%-- mas_find_rev |--0.12%-- unmap_page_range |--0.12%-- tlb_finish_mmu |--0.09%-- tlb_gather_mmu --0.02%-- memset Children Self Command Symbol 60296985 0 unknown kthread 60011285 99995 unknown oom_reaper 33541180 6928225 unknown unmap_page_range 23670245 5414015 unknown folio_remove_rmap_ptes 21027520 1757055 unknown free_pages_and_swap_cache 19399030 2171320 unknown tlb_finish_mmu 18970480 885670 unknown release_pages 13785025 13785025 unknown cgroup_rstat_updated 11442285 11442285 unknown _raw_spin_unlock_irqrestore 7928175 1871335 unknown folios_put_refs 4742620 371410 unknown free_unref_page_list 3928375 942810 unknown free_unref_folios 3842665 14285 unknown tlb_flush_mmu 3385545 728535 unknown free_unref_page_commit 585685 571400 unknown __pte_offset_map_lock
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