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Re: [RFC PATCH v3 2/3] grep: make PCRE2 aware of custom allocator

From
René Scharfe <l.s.r@web.de>
Date
Aug 8, 2019, 07:07 UTC
Message-ID
<f6056e0c-fe7f-30b3-c2d7-bba2b44d6888@web.de>
In-Reply-To
<CAPUEspj4CrEk6u4+8a5UBisxWsXcwOrOPQ5s9TktA6dZx5s+uQ@mail.gmail.com>
Am 08.08.19 um 04:35 schrieb Carlo Arenas:
Show 9 quoted lines
> On Wed, Aug 7, 2019 at 6:03 AM René Scharfe <l.s.r@web.de> wrote:
>>
>> Am 07.08.19 um 11:49 schrieb Carlo Arenas:
>>> was hoping will perform better but it seems that testing can be done
>>> only in windows
>>
>> nedmalloc works on other platforms as well.
>
> I meant[1] it works reliably enough to be useful for performance testing.

You mentioned being concerned about performance several times and I wondered why each time. I'd expect no measurable difference between using a custom global context and the internal one of PCRE2 -- setting two function pointers surely can't take very long, can it? But measuring is better than guessing, of course.

> goes without saying that the fact that I am using a virtualbox with 2
> CPUs running Debian 10 on top of macOS (a macbook pro with 4 cores)
> and the test uses by default 8 threads, doesn't help,
nedmalloc is supposed to run on macOS as well.
Show 84 quoted lines
> but to share my
> pain here is the result of running p7820 with my last reroll on top of
> pu, comparing a build of the same code without NED (this tree) with
> one with it (HEAD)
>
> Test                                               this tree
> HEAD
> -------------------------------------------------------------------------------------------
> 7820.1: basic grep -i 'how.to'                     0.89(1.12+0.46)
> 0.95(1.23+0.49) +6.7%
> 7820.2: extended grep -i 'how.to'                  0.90(1.12+0.49)
> 0.92(1.19+0.46) +2.2%
> 7820.3: perl grep -i 'how.to'                      0.54(0.30+0.52)
> 0.53(0.39+0.52) -1.9%
> 7820.5: basic grep -i '^how to'                    0.89(1.13+0.47)
> 0.91(1.13+0.49) +2.2%
> 7820.6: extended grep -i '^how to'                 0.84(1.04+0.49)
> 0.94(1.27+0.47) +11.9%
> 7820.7: perl grep -i '^how to'                     0.49(0.34+0.47)
> 0.51(0.36+0.49) +4.1%
> 7820.9: basic grep -i '[how] to'                   1.51(2.31+0.51)
> 1.55(2.38+0.51) +2.6%
> 7820.10: extended grep -i '[how] to'               1.50(2.20+0.59)
> 1.56(2.30+0.62) +4.0%
> 7820.11: perl grep -i '[how] to'                   0.67(0.50+0.52)
> 0.62(0.50+0.55) -7.5%
> 7820.13: basic grep -i '\(e.t[^ ]*\|v.ry\) rare'   2.58(4.39+0.56)
> 2.64(4.45+0.60) +2.3%
> 7820.14: extended grep -i '(e.t[^ ]*|v.ry) rare'   2.60(4.41+0.56)
> 2.66(4.58+0.56) +2.3%
> 7820.15: perl grep -i '(e.t[^ ]*|v.ry) rare'       1.17(1.66+0.53)
> 1.23(1.84+0.45) +5.1%
> 7820.17: basic grep -i 'm\(ú\|u\)lt.b\(æ\|y\)te'   1.12(1.54+0.51)
> 1.14(1.70+0.44) +1.8%
> 7820.18: extended grep -i 'm(ú|u)lt.b(æ|y)te'      1.09(1.54+0.48)
> 1.14(1.62+0.49) +4.6%
> 7820.19: perl grep -i 'm(ú|u)lt.b(æ|y)te'          0.87(1.09+0.46)
> 0.90(1.20+0.43) +3.4%
>
> and here one comparing two builds (both with NED)
>
> Test                                               origin/pu
> HEAD
> -------------------------------------------------------------------------------------------
> 7820.1: basic grep -i 'how.to'                     1.00(1.24+0.55)
> 0.94(1.19+0.52) -6.0%
> 7820.2: extended grep -i 'how.to'                  0.90(1.15+0.49)
> 0.93(1.23+0.44) +3.3%
> 7820.3: perl grep -i 'how.to'                      0.52(0.37+0.51)
> 0.59(0.34+0.53) +13.5%
> 7820.5: basic grep -i '^how to'                    0.89(1.16+0.48)
> 0.90(1.17+0.47) +1.1%
> 7820.6: extended grep -i '^how to'                 0.92(1.17+0.50)
> 0.92(1.20+0.45) +0.0%
> 7820.7: perl grep -i '^how to'                     0.45(0.33+0.42)
> 0.54(0.29+0.57) +20.0%
> 7820.9: basic grep -i '[how] to'                   1.60(2.46+0.52)
> 1.61(2.39+0.62) +0.6%
> 7820.10: extended grep -i '[how] to'               1.71(2.67+0.56)
> 1.57(2.41+0.54) -8.2%
> 7820.11: perl grep -i '[how] to'                   0.66(0.61+0.51)
> 0.59(0.44+0.51) -10.6%
> 7820.13: basic grep -i '\(e.t[^ ]*\|v.ry\) rare'   2.69(4.49+0.66)
> 2.67(4.49+0.60) -0.7%
> 7820.14: extended grep -i '(e.t[^ ]*|v.ry) rare'   2.67(4.49+0.64)
> 2.64(4.54+0.54) -1.1%
> 7820.15: perl grep -i '(e.t[^ ]*|v.ry) rare'       1.23(1.80+0.47)
> 1.25(1.89+0.46) +1.6%
> 7820.17: basic grep -i 'm\(ú\|u\)lt.b\(æ\|y\)te'   1.13(1.64+0.47)
> 1.14(1.64+0.48) +0.9%
> 7820.18: extended grep -i 'm(ú|u)lt.b(æ|y)te'      1.16(1.68+0.46)
> 1.20(1.60+0.60) +3.4%
> 7820.19: perl grep -i 'm(ú|u)lt.b(æ|y)te'          0.90(1.16+0.48)
> 0.88(1.17+0.45) -2.2%
>
> with the only relevant line (for my code) being 7820.19 where it would
> seem it performs almost the same (eventhough just adding NED made it
> initially worst)
>
> note though that the fact there are 20% swings in parts of the code
> that hasn't changed
> or that where explicitly #ifdef out of my code changes doesn't give me
> much confidence, but since the windows guys seem to be using NED by
> default, I am hoping it works better there.

These measurement results are quite noisy, so I wouldn't trust them too much. nedmalloc being slower than the one from a recent glibc version is not very surprising given this statement from its home page, https://www.nedprod.com/programs/portable/nedmalloc/:

   "Windows 7, Linux 3.x, FreeBSD 8, Mac OS X 10.6 all contain
    state-of-the-art allocators and no third party allocator is
    likely to significantly improve on them in real world results"

In particular I don't think that these results justify coupling the use of nedmalloc to the choice of using a custom global context for PCRE2.

I'd expect:
- Without USE_NED_ALLOCATOR: xmalloc() should be used for all
  allocations, including for PCRE2.  Some special exceptions use
  malloc(3) directly, but for most uses we want the consistent
  out-of-memory handling that xmalloc() brings.
- With USE_NED_ALLOCATOR: malloc() and xmalloc() use nedmalloc
  behind the scenes and free() is similarly overridden, so all
  allocations are affected.
- If USE_NED_ALLOCATOR performs worse than the system allocator on
  some system then it's the problem of those that turn on that flag.
Makes sense?
René
Previous: Carlo ArenasNext: Carlo Arenas
Message 25 of 67 in “Fix a problem with PCRE2 and nedmalloc, found via Azure Pipelines”
  1. 0/1 Fix a problem with PCRE2 and nedmalloc, found via Azure PipelinesJohannes Schindelin via GitGitGadget, Aug 5, 2019
  2. 1/1 pcre2: allow overriding the system allocatorJohannes Schindelin via GitGitGadget, Aug 5, 2019
  3. Carlo ArenasAug 5, 2019
  4. Carlo ArenasAug 5, 2019
  5. Johannes SchindelinAug 5, 2019
  6. Johannes SchindelinAug 5, 2019
  7. Junio C HamanoAug 5, 2019
  8. Carlo ArenasAug 6, 2019
  9. 0/3 grep: no leaks (WIP)Carlo Marcelo Arenas Belón, Aug 6, 2019
  10. 1/3 grep: make PCRE1 aware of custom allocatorCarlo Marcelo Arenas Belón, Aug 6, 2019
  11. Johannes SchindelinAug 8, 2019
  12. Carlo ArenasAug 8, 2019
  13. 3/3 grep: avoid leak of chartables in PCRE2Carlo Marcelo Arenas Belón, Aug 6, 2019
  14. 2/3 grep: make PCRE2 aware of custom allocatorCarlo Marcelo Arenas Belón, Aug 6, 2019
  15. Johannes SchindelinAug 8, 2019
  16. Carlo ArenasAug 8, 2019
  17. 0/3 grep: no leaks or crashes (windows testing needed)Carlo Marcelo Arenas Belón, Aug 6, 2019
  18. 2/3 grep: make PCRE2 aware of custom allocatorCarlo Marcelo Arenas Belón, Aug 6, 2019
  19. René ScharfeAug 7, 2019
  20. Carlo ArenasAug 7, 2019
  21. René ScharfeAug 7, 2019
  22. 1/2 nedmalloc: do assignments only after the declaration sectionRené Scharfe, Aug 7, 2019
  23. 2/2 nedmalloc: avoid compiler warning about unused valueRené Scharfe, Aug 7, 2019
  24. Carlo ArenasAug 8, 2019
  25. René ScharfeAug 8, 2019
  26. Carlo ArenasAug 8, 2019
  27. René ScharfeAug 8, 2019
  28. Johannes SchindelinAug 8, 2019
  29. Junio C HamanoAug 7, 2019
  30. 1/3 grep: make PCRE1 aware of custom allocatorCarlo Marcelo Arenas Belón, Aug 6, 2019
  31. 3/3 grep: avoid leak of chartables in PCRE2Carlo Marcelo Arenas Belón, Aug 6, 2019
  32. Junio C HamanoAug 6, 2019
  33. 0/3 grep: no leaks or crashes (windows testing needed)Carlo Marcelo Arenas Belón, Aug 7, 2019
  34. 1/3 grep: make PCRE1 aware of custom allocatorCarlo Marcelo Arenas Belón, Aug 7, 2019
  35. 2/3 grep: make PCRE2 aware of custom allocatorCarlo Marcelo Arenas Belón, Aug 7, 2019
  36. Junio C HamanoAug 7, 2019
  37. 3/3 grep: avoid leak of chartables in PCRE2Carlo Marcelo Arenas Belón, Aug 7, 2019
  38. 0/3 grep: almost no more leaks, hopefully no crashesCarlo Marcelo Arenas Belón, Aug 9, 2019
  39. 1/3 grep: make PCRE1 aware of custom allocatorCarlo Marcelo Arenas Belón, Aug 9, 2019
  40. 3/3 grep: avoid leak of chartables in PCRE2Carlo Marcelo Arenas Belón, Aug 9, 2019
  41. 2/3 grep: make PCRE2 aware of custom allocatorCarlo Marcelo Arenas Belón, Aug 9, 2019
  42. Johannes SchindelinAug 27, 2019
  43. Carlo ArenasAug 27, 2019
  44. Junio C HamanoOct 3, 2019
  45. Johannes SchindelinOct 3, 2019
  46. Carlo ArenasOct 3, 2019
  47. Johannes SchindelinOct 3, 2019
  48. Junio C HamanoOct 3, 2019
  49. Carlo ArenasAug 9, 2019
  50. René ScharfeAug 9, 2019
  51. Junio C HamanoAug 9, 2019
  52. Johannes SchindelinAug 9, 2019
  53. SQUASHCarlo Marcelo Arenas Belón, Aug 10, 2019
  54. René ScharfeAug 10, 2019
  55. Carlo ArenasAug 10, 2019
  56. René ScharfeAug 10, 2019
  57. Carlo ArenasAug 12, 2019
  58. René ScharfeAug 12, 2019
  59. Carlo ArenasAug 12, 2019
  60. Johannes SchindelinAug 10, 2019
  61. Carlo ArenasAug 10, 2019
  62. René ScharfeAug 10, 2019
  63. Carlo ArenasAug 10, 2019
  64. René ScharfeAug 10, 2019
  65. Johannes SchindelinAug 8, 2019
  66. Carlo ArenasAug 9, 2019
  67. Johannes SchindelinAug 9, 2019

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