Generation of static tables in embedded memory with dense scheduling

In a real-time context, designing the software relies on insuring deterministic behavior and predictability. With system controlling several sensors and actuators sampled at different rates the scheduling theory associates the notion of Hyperperiod. It is a major factor of complexity whether for scheduling validation (simulation), or for generation of the corresponding tables in the case of pure off-line schedules. This paper presents a compression method of static real-time schedules and a design flow for generating real-time hardware schedulers. The goal is to minimize the size in embedded memory of the scheduling tables defined at compile-time. This method exploits Idle times in multiprocessors systems in order to identify cyclic patterns called dense schedules. When applied to our case studies, the average compression rate of our technique is near 90% of the initial schedules size.

[1]  J. P. van den Berg.  Path planning in dynamic environments , 2007 .

[2]  Krithi Ramamritham,et al.  Allocation and Scheduling of Precedence-Related Periodic Tasks , 1995, IEEE Trans. Parallel Distributed Syst..

[3]  Paul Caspi,et al.  From Control Loops to Real-Time Programs , 2005, Handbook of Networked and Embedded Control Systems.

[4]  D. Parnas,et al.  On satisfying timing constraints in hard-real-time systems , 1991, SIGSOFT '91.

[5]  Liliana Cucu-Grosjean,et al.  Periodic real-time scheduling: from deadline-based model to latency-based model , 2008, Ann. Oper. Res..

[6]  Jean J. Labrosse,et al.  MicroC/OS-II: The Real Time Kernel , 1998 .

[7]  Gerhard Fohler,et al.  Joint scheduling of distributed complex periodic and hard aperiodic tasks in statically scheduled systems , 1995, Proceedings 16th IEEE Real-Time Systems Symposium.

[8]  Giorgio Buttazzo,et al.  Hard Real-Time Computing Systems: Predictable Scheduling Algorithms and Applications , 1997 .

[9]  H. Neil Geismar,et al.  Robotic Cells with Parallel Machines: Throughput Maximization in Constant Travel-Time Cells , 2004, J. Sched..

[10]  Emmanuel Grolleau,et al.  Off-Line Computation of Real-Time Schedules Using Petri Nets , 2002, Discret. Event Dyn. Syst..

[11]  Emilia Farcas,et al.  Hyperperiod bus scheduling and optimizations for TDL components , 2007, 2007 IEEE Conference on Emerging Technologies and Factory Automation (EFTA 2007).

[12]  Joël Goossens,et al.  Limitation of the hyper-period in real-time periodic task set generation , 2001 .

[13]  J. Stankovic,et al.  Buttazzo Hard Real-Time Computing Systems Predictable Scheduling Algorithms and Applications , 2011 .

[14]  Krithi Ramamritham,et al.  Scheduling algorithms and operating systems support for real-time systems , 1994, Proc. IEEE.

[15]  Günter Grünsteidl,et al.  TTP - A Protocol for Fault-Tolerant Real-Time Systems , 1994, Computer.

[16]  Niraj K. Jha,et al.  COSYN: Hardware-software co-synthesis of heterogeneous distributed embedded systems , 1999, IEEE Trans. Very Large Scale Integr. Syst..