Parallel Slowdown

Parallel slowdown is a phenomenon in parallel computing where parallelization of a parallel computer program beyond a certain point causes the program to run slower (take more time to run to completion).

Parallel slowdown is typically the result of a communications bottleneck. As more processing nodes are added, each processing node spends progressively more time doing communication than useful processing. At some point, the communications overhead created by adding another processing node surpasses the increased processing power that node provides, and parallel slowdown occurs.

Parallel computing
General
  • Cloud computing
  • High-performance computing
  • Cluster computing
  • Distributed computing
  • Grid computing
Levels
  • Bit
  • Instruction
  • Data
  • Task
Threads
  • Superthreading
  • Hyperthreading
Theory
  • Amdahl's law
  • Gustafson's law
  • Cost efficiency
  • Karp–Flatt metric
  • slowdown
  • speedup
Elements
  • Process
  • Thread
  • Fiber
  • PRAM
  • Instruction window
Coordination
  • Multiprocessing
  • Multithreading (computer architecture)
  • Memory coherency
  • Cache coherency
  • Cache invalidation
  • Barrier
  • Synchronization
  • Application checkpointing
Programming
  • Models
    • Implicit parallelism
    • Explicit parallelism
    • Concurrency
  • Flynn's taxonomy
    • SISD
    • SIMD
    • MISD
    • MIMD
      • SPMD
  • Thread (computer science)
  • Non-blocking algorithm
Hardware
  • Multiprocessor
    • Symmetric
    • Asymmetric
  • Memory
    • NUMA
    • COMA
    • distributed
    • shared
    • distributed shared
  • SMT
  • MPP
  • Superscalar
  • Vector processor
  • Supercomputer
  • Beowulf
APIs
  • Ateji PX
  • POSIX Threads
  • OpenMP
  • OpenHMPP
  • OpenACC
  • PVM
  • MPI
  • UPC
  • Intel Threading Building Blocks
  • Intel Cilk Plus
  • Boost.Thread
  • Global Arrays
  • Charm++
  • Cilk
  • Coarray Fortran
  • OpenCL
  • CUDA
  • Dryad
  • C++ AMP
Problems
  • Embarrassingly parallel
  • Software lockout
  • Scalability
  • Race condition
  • Deadlock
  • Livelock
  • Starvation
  • Deterministic algorithm
  • Parallel slowdown
  • Category: parallel computing
  • Media related to parallel computing at Wikimedia Commons

Famous quotes containing the word parallel:

    One writes of scars healed, a loose parallel to the pathology of the skin, but there is no such thing in the life of an individual. There are open wounds, shrunk sometimes to the size of a pin-prick but wounds still. The marks of suffering are more comparable to the loss of a finger, or the sight of an eye. We may not miss them, either, for one minute in a year, but if we should there is nothing to be done about it.
    F. Scott Fitzgerald (1896–1940)