Windows NT and Real-Time Operating Systems

• Microsoft Windows NT operating system version 3.1
• Microsoft Windows NT Advanced Server version 3.1

SUMMARY

You can use a variety of criteria to measure the performance of a real-time system. The following are examples of the kinds of measurements that might be used to determine real-time throughput:

• Longest critical region that the kernel blocks task activation during a system call
• Maximum time that interrupts are disabled
• Context switch time (scheduler time to save/restore registers, etc.) for threads within the same process (no change in memory context) and for threads in different processes (save/restore memory context)
• Interrupt response time (latency between the occurrence and execution of the first instruction)
• Interrupt task response time (worst case task dispatch latency for task waiting on the interrupt)
• Performance of interprocess communication facilities (semaphores, queues, pipes, etc.)

MORE INFORMATION

Users often want a total program development/GUI user environment, virtual memory, and so forth, without any corresponding reduction in response time. Real-time systems, however, are dedicated systems for the duration of an "event." During that time, the system is essentially locked, and no other activity can take place except that real-time event. (Note that very few situations demand microsecond or millisecond response time.)

Windows NT has the same basic structure as VMS. Windows NT has more efficient mechanisms than RSX-11M. It has a better design than VAXELN, which is a real-time embedded OS toolkit. All three of these systems are very successful.

Although Windows NT has good real-time capabilities; it is not designed to compete with a special purpose real-time system. If you need such a system, obtain the special real-time hardware and supporting operating system.