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Parallel And Distributed Programming Concept

Load-Link / Store-Conditional

Depends on JourneyParallel And Distributed Programming Statuslearning Tags
  • parallel programming

A pair of atomic instructions. Load-Link (LL) reads a value from a memory location and reserves it. Store-Conditional (SC) writes a new value only if no other process has written to that location since the LL; otherwise it fails.

LL/SC has consensus number ∞ and is equivalent in power to CAS. Unlike CAS, it is naturally immune to the ABA problem because SC fails on any write, not just a value change. Practically, SC can fail spuriously (e.g., due to cache line eviction or context switch). Not supported in MPI-3; CAS is used instead.