SUMMARY: SOFT REAL-TIME ON MULTIPROCESSORS: ARE ANALYSIS-BASED SCHEDULERS REALLYWORTH IT? Christopher J. Kennay, Jonathan L. Hermany, Bj¨orn B. Brandenburgy, Alex F. Millsz, and James H. Andersony Departments of Computer Sciencey and Statistics and Operations Researchz The University of North Carolina at Chapel Hill Presented by Gbadebo Ayoade

Introduction  EDF –earliest deadline first  EDF-HSB allows taskset to be represented as mixture of soft real time and hard real time tasks  It allows for background scheduling and slack reclamation  Hard Realtime Task (HRT)  Soft Realtime Task(SRT)  Best Effort Jobs (BE)

EDF –HSB algorithm Credit :Kenna et al

Partitioning Formula

Experiment  Comparism of EDF-HSB and linux CFS scheduler  Video application: Display and decoding task  Measurement of tardiness and display jitter

Results Credit :Kenna et al

Results Credit :Kenna et al

Contribution  EDF-HSB guarantees Deadline tardiness bound  Stable BE throughput  Better performance due to background scheduling and slack reclamation

Limitations  I/O suspension  Task dependencies  Memory management

SUMMARY: CPU SCHEDULING AND MEMORY MANAGEMENT FOR INTERACTIVE REAL-TIME APPLICATIONS SHINPEI KATO °U YUTAKA ISHIKAWA °U RAGUNATHAN

Introduction  Constant bandwidth server  EDF-WM  EDF-WMR  Flexible CBS  Page swapping  Memory locking

EDF WM Algorithm Credit Shipei et al EDF-WM algorithm schedule tasks in a task set using the normal EDF algorithm and it assigns task i to a CPU that has enough free capacity to run the task, if such CPU is not found, EDF-WM splits the task i relative deadline and its execution cost based on the number of CPUs in the system and assigns each part to different CPUs New deadline = t+ originaldeadline/number of processors

Improvement  EDFWMR - CPU bandwidth reservation  FCBS CPU bandwidth reclamation Flexible CBS is proposed as an improvement to CBS by reclaiming unused reserved bandwidth and adding it to the reserved bandwidth of tasks that are running late

Memory management  RTS memory reservation reduces page swap to disk  Full memory reservation- this lead to wastage of memory resources

Improvement to memory reservation technique  Private-Shared-Anonymous Paging (PSAP). This is a dynamic memory reservation technique.  Memory reclamation  It reduces memory usage of RTS applications

Experiment  Benchmarking of EDF WM against EDF WMR alogorithm using video application  Quality of service measured as stability of frame rate of the video playback.

Results Performance by scheduling algorithms Credit Shipei et al

Results Performance by memory reservation techniques. Credit Shipei et al

Limitations  Grouping decode and display task as one component of a video application  I/O blocking  No consideration for Task dependency