Efficient Implementation of IPCP and DFP
Neil Audsley, Alan Burns · ACM SIGAda Ada Letters · 2015
Most resource control protocols such as IPCP (Immediate Priority Ceiling Protocol) require a kernel system call to implement the necessary control over the shared protected object. This switch can be expensive, involving a potentially slow switch from CPU user-mode to kernel-mode (and back). In this paper we look at two anticipatory schemes (IPCP and DFP - Deadline Floor Protocol) and show how they can be implemented with the minimum number of calls on the kernel. Specifically, no kernel calls are needed when there is no contention, and only one when there is. A standard implementation would need two such calls.