Is Chip-Multiprocessing the End of Real-Time Scheduling?

Chip-multiprocessing is considered the future path for performance enhancements in computer architecture. Eight processor cores on a single chip are state-of-the art and several hundreds of cores on a single die are expected in the near future. General purpose computing is facing the challenge how to use the many cores. However, in embedded real-time systems thread-level parallelism is naturally used. In this paper we assume a system where we can dedicate a single core for each thread. In that case classic real-time scheduling disappears. However, the threads, running on their dedicated core, still compete for a shared resource, the main memory. A time-sliced memory arbiter is used to avoid timing influences between threads. The schedule of the arbiter is integrated into the worst-case execution time (WCET) analysis. The WCET results are used as a feedback to regenerate the arbiter schedule. Therefore, we schedule memory access instead of CPU time.