Interlockedarm

Interlockedarm is a term used in the context of concurrent programming on ARM-based systems to describe a family of synchronization techniques that combine interlocked or atomic operations with ARM’s memory model. The concept centers on using ARM architectural features such as exclusive load/store instructions and associated barriers to implement lock-free and wait-free data structures, as well as safe cross-thread communication, without resorting to heavier locking primitives.

Origins and context: The approach arises from the need for low-latency, low-overhead synchronization on embedded, mobile, and other ARM-based platforms. It leverages the ARM instruction set’s support for atomic read-modify-write sequences and the memory ordering guarantees provided by barrier instructions, enabling developers to build efficient concurrent primitives tailored to ARM processors.

Implementation and patterns: A common pattern involves an atomic loop that performs an exclusive load, computes a new value, and attempts to store it back. If the store fails due to a concurrent modification, the loop retries. To preserve correct ordering around shared memory, barrier instructions such as data memory barriers (DMB) or data synchronization barriers (DSB) are used, or the atomic primitives are implemented with acquire and release semantics on newer ARM variants. ARMv8 also provides stronger native atomics that simplify these patterns. Proper use requires awareness of the differences across ARM versions, as memory ordering and availability of instructions vary.

Applications and scope: Interlockedarm techniques are employed in operating system kernels, device drivers, real-time systems, and high-performance libraries on ARM devices to implement atomic counters, pointers, queues, and lock-free data structures with minimal overhead.

See also: Interlocked operations, ARM architecture, memory barriers, lock-free programming.