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[v3,0/7] mm: Optimize mseal checks

Message ID 20240817-mseal-depessimize-v3-0-d8d2e037df30@gmail.com
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Series mm: Optimize mseal checks | expand

Message

Pedro Falcato Aug. 17, 2024, 12:18 a.m. UTC 
[based on mm-unstable, 651c8c1d7359]

Optimize mseal checks by removing the separate can_modify_mm() step, and
just doing checks on the individual vmas, when various operations are
themselves iterating through the tree. This provides a nice speedup and restores
performance parity with pre-mseal[3].

This series also depends on the powerpc series that removes arch_unmap[2]. This
series is already in mm-unstable.

will-it-scale mmap1_process[1] -t 1 results:

commit 3450fe2b574b4345e4296ccae395149e1a357fee:

min:277605 max:277605 total:277605
min:281784 max:281784 total:281784
min:277238 max:277238 total:277238
min:281761 max:281761 total:281761
min:274279 max:274279 total:274279
min:254854 max:254854 total:254854
measurement
min:269143 max:269143 total:269143
min:270454 max:270454 total:270454
min:243523 max:243523 total:243523
min:251148 max:251148 total:251148
min:209669 max:209669 total:209669
min:190426 max:190426 total:190426
min:231219 max:231219 total:231219
min:275364 max:275364 total:275364
min:266540 max:266540 total:266540
min:242572 max:242572 total:242572
min:284469 max:284469 total:284469
min:278882 max:278882 total:278882
min:283269 max:283269 total:283269
min:281204 max:281204 total:281204

After this patch set:

min:280580 max:280580 total:280580
min:290514 max:290514 total:290514
min:291006 max:291006 total:291006
min:290352 max:290352 total:290352
min:294582 max:294582 total:294582
min:293075 max:293075 total:293075
measurement
min:295613 max:295613 total:295613
min:294070 max:294070 total:294070
min:293193 max:293193 total:293193
min:291631 max:291631 total:291631
min:295278 max:295278 total:295278
min:293782 max:293782 total:293782
min:290361 max:290361 total:290361
min:294517 max:294517 total:294517
min:293750 max:293750 total:293750
min:293572 max:293572 total:293572
min:295239 max:295239 total:295239
min:292932 max:292932 total:292932
min:293319 max:293319 total:293319
min:294954 max:294954 total:294954

This was a Completely Unscientific test but seems to show there were around 5-10% gains on ops per second.

Oliver performed his own tests and showed[3] a similar ~5% gain in them.

[1]: mmap1_process does mmap and munmap in a loop. I didn't bother testing multithreading cases.
[2]: https://lore.kernel.org/all/20240807124103.85644-1-mpe@ellerman.id.au/
[3]: https://lore.kernel.org/all/ZrMMJfe9aXSWxJz6@xsang-OptiPlex-9020/
Link: https://lore.kernel.org/all/202408041602.caa0372-oliver.sang@intel.com/

Changes in v3:
 - Moved can_modify_vma to vma.h instead of internal.h (Lorenzo)
 - Fixed a bug in munmap where we used the wrong VMA pointer
 - Added tests for the previous munmap bug
 - Moved the mremap source vma check upwards, to stop us from unmapping
   dest while the source is sealed (Liam)
Changes in v2:
 - Rebased on top of mm-unstable
 - Removed a superfluous check in mremap (Jeff Xu)

Signed-off-by: Pedro Falcato <pedro.falcato@gmail.com>
---
Pedro Falcato (7):
      mm: Move can_modify_vma to mm/vma.h
      mm/munmap: Replace can_modify_mm with can_modify_vma
      mm/mprotect: Replace can_modify_mm with can_modify_vma
      mm/mremap: Replace can_modify_mm with can_modify_vma
      mseal: Replace can_modify_mm_madv with a vma variant
      mm: Remove can_modify_mm()
      selftests/mm: add more mseal traversal tests

 mm/internal.h                           |  16 -----
 mm/madvise.c                            |  13 +---
 mm/mmap.c                               |  11 +---
 mm/mprotect.c                           |  12 +---
 mm/mremap.c                             |  32 ++-------
 mm/mseal.c                              |  55 ++--------------
 mm/vma.c                                |  19 ++++--
 mm/vma.h                                |  35 ++++++++++
 tools/testing/selftests/mm/mseal_test.c | 111 +++++++++++++++++++++++++++++++-
 9 files changed, 174 insertions(+), 130 deletions(-)
---
base-commit: 651c8c1d735983040bec4f71d0e2e690f3c0fc2d
change-id: 20240816-mseal-depessimize-f39d9f4c32c6

Best regards,