OTP20 officially introduced dirty schedulers. In this talk, we'll cover why they're part of OTP and what function they perform. Using Rust NIFs, we'll compare schedulers and dirty schedulers to illustrate the trade-offs between scheduler types. By the talk's end, it should be apparent why dirty schedulers are part of OTP and how and when you should consider using them.

1. TAKE YOUR TIME

2. BEN MARX
@bgmarx
ARCHITECT

4. AdoptingElixir_Workshop_2018
25% off til 9/15

5. HOW
SCHEDULERS
WORK

6. NIFS
BRIEFLY

7. DIRTY
SCHEDULERS

8. RUST

9. NIFS OR NAY?

10. SCHEDULERS

12. PREEMPTIVE

13. RUN QUEUE

14. MIGRATION
LOGIC

15. RUN QUEUE 2SCHEDULER 2
RUN QUEUE NSCHEDULER N
RUN QUEUE 1SCHEDULER1
MIGRATION LOGIC

16. FINELY
TUNED

17. 1MS

18. SCHEDULER
COLLAPSE

19. SCHEDULERS

20. NIFS

21. NATIVELY
IMPLEMENTED
FUNCTIONS

23. WRITTEN IN C

26. NIFS

27. DIRTY
SCHEDULERS

28. “Due to heroic efforts by Steve Vinoski, Rickard Green, and
Sverker Eriksson, we have an (experimental) so-called
dirty-scheduler (DS) NIF API in the Erlang runtime, which
has been somewhat stable since release 17.3.”
https://medium.com/@jlouis666/erlang-dirty-scheduler-overhead-6e1219dcc7

31. IO INTENSIVE
OR
CPU INTENSIVE

32. DIRTY NIF FLAGS
ERL_NIF_DIRTY_JOB_CPU_BOUND
ERL_NIF_DIRTY_JOB_IO_BOUND
http://erlang.org/doc/man/erl_nif.html

33. RUN QUEUE CPUDIRTY CPU
RUN QUEUE NSCHEDULER N
RUN QUEUE IODIRTY IO
MIGRATION LOGIC

34. DIRTY SCHEDULERS
ARE
UNMANAGED
https://github.com/erlang/otp/blob/maint/erts/emulator/internal_doc/ThreadProgress.md

35. DIRTY SCHEDULERS
AREN’T
FREE

37. RE-SCHEDULE DIRTY
http://erlang.org/doc/man/erl_nif.html#enif_schedule_nif
ENIF_SCHEDULE _NIF
DIRTY TO “CLEAN”

38. LONG SCHEDULING
http://erlang.org/doc/man/erlang.html#system_monitor-2
erlang:system_monitor(Pid, [{long_schedule,Time}])

39. DIRTY
SCHEDULERS

40. RUST

41. MEMORY SAFE

42. FOND OF
DIALYZER?

43. BLAZINGLY
FAST

44. THREAD
SAFETY

45. “SAFE C”

47. SYSTEMS
PROGRAMMING

48. https://mgattozzi.com/avoiding-logic-errors

49. RUSTLER
https://github.com/hansihe/rustler/

51. https://github.com/hansihe/rustler/blob/b6578ea3999fd42f377c2497d8fae0bd629b927d/rustler/src/schedule.rs

52. https://github.com/hansihe/rustler/blob/b6578ea3999fd42f377c2497d8fae0bd629b927d/rustler/src/schedule.rs

53. https://github.com/hansihe/rustler/blob/b6578ea3999fd42f377c2497d8fae0bd629b927d/rustler/src/schedule.rs

54. https://github.com/hansihe/rustler/blob/b6578ea3999fd42f377c2497d8fae0bd629b927d/rustler/src/schedule.rs

55. https://github.com/hansihe/rustler/blob/b6578ea3999fd42f377c2497d8fae0bd629b927d/rustler/src/schedule.rs

56. https://github.com/hansihe/rustler/blob/b6578ea3999fd42f377c2497d8fae0bd629b927d/rustler/src/schedule.rs

57. https://github.com/hansihe/rustler/blob/b6578ea3999fd42f377c2497d8fae0bd629b927d/rustler/src/schedule.rs

58. https://github.com/hansihe/rustler/blob/b6578ea3999fd42f377c2497d8fae0bd629b927d/rustler/src/schedule.rs

59. UNSAFE

60. DIRTY
FUNCTIONS

61. https://github.com/hansihe/rustler/blob/b6578ea3999fd42f377c2497d8fae0bd629b927d/rustler_tests/src/test_dirty.rs

62. https://github.com/hansihe/rustler/blob/b6578ea3999fd42f377c2497d8fae0bd629b927d/rustler_tests/src/lib.rs

63. https://github.com/hansihe/rustler/blob/b6578ea3999fd42f377c2497d8fae0bd629b927d/rustler_tests/test/dirty_test.exs

64. RUST

65. NIFS OR NAY?

66. SERVICES

67. CRITICAL

70. LINKS
https://bgmarx.com/2018/08/01/getting-started-with-rustler/
https://bgmarx.com/2018/08/15/using-dirty-
schedulers-with-rustler/

71. THANK YOU
@BGMARX
IMAGE CREDITS
https://wallpaper-gallery.net/single/vaporwave-background-hd-14.html
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https://wallpaper-gallery.net/single/glitch-wallpaper-hd-11.html

72. THANK YOU
@BGMARX
RESOURCEShttp://hansihe.com/erlang/elixir/c/2016/07/26/erlang-nif-preemptive-scheduling.html
https://medium.com/@jlouis666/erlang-dirty-scheduler-overhead-6e1219dcc7
http://erlang.org/doc/man/erl_nif.html
https://www.youtube.com/watch?v=FYQcn9zcZVA
https://www.youtube.com/watch?v=lSLTwWqTbKQ
https://hamidreza-s.github.io/erlang/scheduling/real-time/preemptive/migration/2016/02/09/erlang-scheduler-
details.html
https://jlouisramblings.blogspot.com/2013/01/how-erlang-does-scheduling.html
https://www.rust-lang.org/en-US/
http://www.erlang-factory.com/upload/presentations/105/KennethLundin-ErlangFactory2009London-
AboutErlangOTPandMulti-coreperformanceinparticular.pdf
https://github.com/vinoski/bitwise

73. THANK YOU
@BGMARX
QUESTIONS?
@bgmarx