Abstract

We present the design and implementation of a soft real time CPU server for the time-sensitive multimedia applications in the Windows NT environment. The server is a user-level daemon process from which multimedia applications can request and acquire periodic processing time in the well-known form of (processing time per period). Our server is based on a careful manipulation of the real time(RT) priority class, and it does not require any modifications to the kernel. It provides (1) the rate monotonic scheduling algorithm, (2) support for multiple processors (SMP model), (3) limited overrun protection among real-time(RT) processes, (4) fair allocation between the RT and time sharing (TS) processes so that TS processes are not starved for processing time, (5) accessibility by a normal user privilege, and (6) an efficient implementation. We have implemented the CPU scheduling server on top of the Windows NT 4.0 operating system with dual Pentium processors, and we have shown through experiments that our CPU scheduling server provides good soft real time support for the multimedia applications.

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