High-Performance Embedded Computing

234 Chapter 4 Processes and Operating Systems

Given the set of semaphores that are currently locked by processes other than i,

we call the semaphore in that set with the highest priority ceiling S*. For process

i to obtain semaphore S

j

, it must have a priority higher than Π(S*). While in a

critical section, process i inherits the priority of the highest-priority job that may

be blocked by process i; priorities are inherited transitively.

Sha et al. extended Liu and Layland’s analysis of RMS (namely, EQ 4-5) to

determine the schedulability of tasks under the priority ceiling protocol. If B

i

is the

worst-case time that process i can be blocked by lower-priority processes, then

. (EQ 4-8)

hot swapping Some systems may use several implementations of a process ...