priority inheritance


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priority inheritance

(parallel)
A technique for avoiding priority inversion by temporarily raising the prioriry of all processes that want to access a shared resource to the highest priority level of any of them. Priority inversion occurs where a low priority process, L is holding a resource required by a high priority process, H, but L is not running because a medium priority process, M is running. Under priority inheritance, L temporarily inherits H's priority, allowing L to run and release the resource H is waiting for.

For example, an ambulance (H) is stuck behind a lorry (L) waiting at a junction (the shared resource) for a gap in a line of cars (M) using the junction. Applying priority inheritance, the cars give way to the lorry as they would to the ambulance, thus allowing the lorry and then the ambulance to use the junction.
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References in periodicals archive ?
SEM_PRTYINHERIT: If it is set, the RT-kernel applies the Basic Priority Inheritance Protocol to RT-Semaphore operations.
Star/OS supports priority inheritance in situations such as Ada rendezvous.
Episode 2: A guest interview with Thomas Gleixner, one of the main contributors to the real-time patches for the Linux kernel, covering real-time Linux for embedded systems, features of real-time like priority inheritance and high resolution timers, and upcoming improvements to the Linux kernel to support additional real-time functionality.
18 kernel include priority inheritance support to prevent priority inversions, and extensions to the generic interrupt handling layer across all architectures, including established embedded architectures such as ARM.
1 has the capability to perform kernel crash dumps, remote debugging over Ethernet for distributed environments, enhanced priority inheritance for real-time mission-critical applications, and the latest NVIDIA driver for image generation.
ThreadX also includes extremely fast software timers, priority inheritance and preemption-threshhold(TM), a mechanism to help reduce context switching.
Key RedHawk real-time enhancements include processor shielding on a per CPU basis, priority inheritance, minimal dispatch latencies, cross-processor interrupt reduction, user-level real-time Hyper-Threading control, non-preemptible spin locks and many additional improvements.
6-based Linux distribution and advanced real-time capabilities, including schedulable hard and soft interrupt handlers, priority inheritance mutexes and a fully preemptible kernel.
6-based Linux distribution featuring advanced real-time capabilities, including schedulable hard and soft interrupt handlers, priority inheritance mutexes and a fully preemptible kernel.

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