Difference between revisions of "User:Cmpxchg"
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In computer science, compare-and-swap (CAS) is an atomic instruction used in multithreading to achieve synchronization. It compares the contents of a memory location to a given value and, only if they are the same, modifies the contents of that memory location to a given new value. The atomicity guarantees that the new value is calculated based on up-to-date information; if the value had been updated by another thread in the meantime, the write would fail. The result of the operation must indicate whether it performed the substitution; this can be done either with a simple Boolean response (this variant is often called compare-and-set), or by returning the value read from the memory location (not the value written to it). | In computer science, compare-and-swap (CAS) is an atomic instruction used in multithreading to achieve synchronization. It compares the contents of a memory location to a given value and, only if they are the same, modifies the contents of that memory location to a given new value. The atomicity guarantees that the new value is calculated based on up-to-date information; if the value had been updated by another thread in the meantime, the write would fail. The result of the operation must indicate whether it performed the substitution; this can be done either with a simple Boolean response (this variant is often called compare-and-set), or by returning the value read from the memory location (not the value written to it). | ||
Revision as of 22:15, 16 December 2012
| TechInc Member | |
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| nickname | cmpxchg |
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| Part of Projects | usbtinyisp |
CMPXCHG
In computer science, compare-and-swap (CAS) is an atomic instruction used in multithreading to achieve synchronization. It compares the contents of a memory location to a given value and, only if they are the same, modifies the contents of that memory location to a given new value. The atomicity guarantees that the new value is calculated based on up-to-date information; if the value had been updated by another thread in the meantime, the write would fail. The result of the operation must indicate whether it performed the substitution; this can be done either with a simple Boolean response (this variant is often called compare-and-set), or by returning the value read from the memory location (not the value written to it).
