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A Soft Real-Time Scheduling Server in UNIX Operating System (Problem…
A Soft Real-Time Scheduling Server in UNIX Operating System
The Soft realtime server architecture
the broker
share memory object where the broker writes
contains a repeatable frame of slots
the dispatcher
the dispatcher read the table
created by broker and killed when no real-time processes
contains
the shared memory dispatch table
a pointer to the next dispatching slot
The dispatch table
receives requests from client real-time processes
new schedule will be write to the dispatch table
is a root daemon process(running at the normal dynamic priority)
Problem
CPU capacity
fairness problem
RT and non-RT application must share the CPU time fairly
enforcement problem
high priority process case stravation, bolck the system
security problem
root privilege
implementation
SUN Solar 2.5 Implementation
Protection between class
Start-time Fair Queuing algoruthm
CPU resources partitioned in to hierarchical classes
Best effort classes
Real time classes
properties
scheduling process can be implemented as an user-level application
low compulation overhead
provides the flexibility to implement any scheduling algorithm
provide from this paper
Design the Soft Real time Server Architecture
Implement Rate Monotonic Scheduling
Provide protection among real-time processes