Non-deterministic parallelism considered useful Derek G. Murray - - PowerPoint PPT Presentation

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non deterministic parallelism considered useful
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Non-deterministic parallelism considered useful Derek G. Murray - - PowerPoint PPT Presentation

Nov 10, 2023 324 likes •535 views

Non-deterministic parallelism considered useful Derek G. Murray Steven Hand University of Cambridge 1. Parallelization 2. Synchronization 3. Scheduling 4. Load balancing 5. Communication 6. Fault tolerance 7. Guaranteed termination 1.

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SLIDE 1

Non-deterministic parallelism considered useful

Derek G. Murray Steven Hand University of Cambridge

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SLIDE 2
  • 1. Parallelization
  • 2. Synchronization
  • 3. Scheduling
  • 4. Load balancing
  • 5. Communication
  • 6. Fault tolerance
  • 7. Guaranteed termination
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SLIDE 3
  • 1. Parallelization
  • 2. Synchronization
  • 3. Scheduling
  • 4. Load balancing
  • 5. Communication
  • 6. Fault tolerance
  • 7. Guaranteed termination

while ¡(x) ¡{ ¡ ¡ ¡ ¡ ¡… ¡ } ¡

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SLIDE 4
  • 1. Parallelization
  • 2. Synchronization
  • 3. Scheduling
  • 4. Load balancing
  • 5. Communication
  • 6. Fault tolerance ⇔ Deterministic
  • 7. Guaranteed termination
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SLIDE 5

Real programmers don’t use deterministic parallelism

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SLIDE 6

Real programmers use

  • Async. Networks
  • Real hardware
  • Performance

interference

  • User input
  • Timeouts
  • Signals
  • select() loops
  • Condition variables
  • Mutable state

All of these cause non-determinism!

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SLIDE 7

Example: branch-and-bound

L J M K

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SLIDE 8

T K M J L

Deterministic data flow

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SLIDE 9

Irregular parallelism

K L J M

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SLIDE 10

Irregular parallelism

K L J M T

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SLIDE 11

T K M

SELECT

J L

Non-deterministic select

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SLIDE 12

Non-deterministic select

K L J M T

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SLIDE 13

Non-deterministic select

K L J M T

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SLIDE 14

K M J L

Asynchronous signals

new bounds work stealing/ shedding

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SLIDE 15

Asynchronous signals

K L J M

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SLIDE 16

Asynchronous signals

K L J M

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SLIDE 17
  • 1. Parallelization
  • 2. Synchronization
  • 3. Scheduling
  • 4. Load balancing
  • 5. Communication
  • 6. Fault tolerance
  • 7. Guaranteed termination
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SLIDE 18
  • 1. Parallelization
  • 2. Synchronization
  • 3. Scheduling
  • 4. Load balancing
  • 5. Communication
  • 6. Fault tolerance
  • 7. Guaranteed termination
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SLIDE 19

Challenge: dealing with faults

  • Fail everything
  • Error codes/exceptions
  • Bounded non-determinism
  • Checkpoints
  • Record and replay
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SLIDE 20

Conclusions

  • Many benefits of non-determinism

– Performance, adaptability, interactivity

  • System must allow non-determinism
  • Determinism at language-level

– For programmers who need training wheels