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litmus test

A tiny two-thread program used to ask a memory model one question: can this particular result ever happen?

A litmus test is a minimal multi-threaded program with a specified final-state condition (store buffering SB, message passing MP, load buffering LB ...) whose allowed or forbidden status characterizes a memory consistency model; results are established by models and exhaustive tools such as herd7, not by timing runs.

Examples

  • Thread 1 runs x = 1; r1 = y, thread 2 y = 1; r2 = x. x86-TSO allows r1 = r2 = 0; sequential consistency does not.

See also

memory consistency model model
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