real-time operating systems for embedded computing
DESCRIPTION
Real-Time Operating Systems for Embedded Computing. 李姿宜 R90921045 2003,06,10. Outline. Motivation Embedded operating systems Real-Time operating systems A case study Conclusion. Motivation. SoC CPU + ASIC + Software Traditional application-specific systems - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Real-Time Operating Systems for Embedded Computing](https://reader030.vdocument.in/reader030/viewer/2022012919/56814487550346895db11d1b/html5/thumbnails/1.jpg)
Real-Time Operating Systems for Embedded Computing
李姿宜 R909210452003,06,10
![Page 2: Real-Time Operating Systems for Embedded Computing](https://reader030.vdocument.in/reader030/viewer/2022012919/56814487550346895db11d1b/html5/thumbnails/2.jpg)
Outline
MotivationEmbedded operating systemsReal-Time operating systemsA case studyConclusion
![Page 3: Real-Time Operating Systems for Embedded Computing](https://reader030.vdocument.in/reader030/viewer/2022012919/56814487550346895db11d1b/html5/thumbnails/3.jpg)
Motivation
SoC CPU + ASIC + Software Traditional application-specific systems
Implemented by algorithm-to-architecture methodology.
Modern Trend : Design Reuse, which software plays an important role, and Real-time operating systems ( RTOS ) is the critical
component
![Page 4: Real-Time Operating Systems for Embedded Computing](https://reader030.vdocument.in/reader030/viewer/2022012919/56814487550346895db11d1b/html5/thumbnails/4.jpg)
Role of RTOS in HW/SW Co-Design
Formal Languages
Partitioning
HW SynthesisSW Synthesis
RTOS Tasks Logic Synthesis
Code Optimization Logic Optimization
Board Level Prototyping
Co-SimulationAnd
Formal Verification
![Page 5: Real-Time Operating Systems for Embedded Computing](https://reader030.vdocument.in/reader030/viewer/2022012919/56814487550346895db11d1b/html5/thumbnails/5.jpg)
A new system-level synthesis flow
System Design
RTOS
Process Management
Interprocess Communication
Memory Management
I/O Management
Algorithm Development
Compilation
Architecture IC Design
![Page 6: Real-Time Operating Systems for Embedded Computing](https://reader030.vdocument.in/reader030/viewer/2022012919/56814487550346895db11d1b/html5/thumbnails/6.jpg)
Embedded Operating System
Task Managementcreate, delete, suspend, resume
Time Managementsystem clock, generate delay
Inter Task Communication and SynchronizationMultitasking
No-OS disable interrupts / enable interruptsWith-OS enter/exit critical section
![Page 7: Real-Time Operating Systems for Embedded Computing](https://reader030.vdocument.in/reader030/viewer/2022012919/56814487550346895db11d1b/html5/thumbnails/7.jpg)
Embedded Operating System (cont’)
Inter Task Communication and SynchronizationWait for event, interruptExchange data, queues, shared memory
Memory Management temporary data buffersallocate, free (critical in ES)
![Page 8: Real-Time Operating Systems for Embedded Computing](https://reader030.vdocument.in/reader030/viewer/2022012919/56814487550346895db11d1b/html5/thumbnails/8.jpg)
Real Time Operating System
Embedded applications can and will respond to external events before deadline
Soft real-time requirements:Breaking the time limit is unwanted, but is not
immediately criticalHard real-time requirements
Breaking the limit is always seen as a fundamental failure
![Page 9: Real-Time Operating Systems for Embedded Computing](https://reader030.vdocument.in/reader030/viewer/2022012919/56814487550346895db11d1b/html5/thumbnails/9.jpg)
Real Time Operating System Characteristics
Bounded Interrupt ServicingPriority Based SchedulingPre-Emptive TasksScalability
![Page 10: Real-Time Operating Systems for Embedded Computing](https://reader030.vdocument.in/reader030/viewer/2022012919/56814487550346895db11d1b/html5/thumbnails/10.jpg)
Previous RTOS Research(1/2)
Scheduling of the CPU : Central purpose of and RTOSA complete process : waiting, ready, and
executingScheduling policies
Cooperative schedulerStatic priority-driven schedulerDynamic priority-driven scheduler
![Page 11: Real-Time Operating Systems for Embedded Computing](https://reader030.vdocument.in/reader030/viewer/2022012919/56814487550346895db11d1b/html5/thumbnails/11.jpg)
Previous RTOS Research(2/2)
Scheduling methodology examples Rate Monotonic algorithm by Liu & Layland
static priorities based on periods higher priorities to shorter periods
optimal among all static priority schemes
Earliest-deadline First dynamic priority assignment closer a task’s deadline, higher is it priority applicable to both periodic and aperiodic tasks need to calculate priorities when new tasks arrives
more expensive in terms of run-time overheads
![Page 12: Real-Time Operating Systems for Embedded Computing](https://reader030.vdocument.in/reader030/viewer/2022012919/56814487550346895db11d1b/html5/thumbnails/12.jpg)
Commercial RTOS Offerings
Integrated Systems (pSOS system), WindRiver (VxWorks), Microtec Research (VRTX), Microware Systems (OS-9), QNX (QNX), Lynx Real-Time system (LynxOS), Microsoft (Windows-CE)
Practical application issuesMemory requrimentContext switch time Interrupt latency
![Page 13: Real-Time Operating Systems for Embedded Computing](https://reader030.vdocument.in/reader030/viewer/2022012919/56814487550346895db11d1b/html5/thumbnails/13.jpg)
An example of Commercial RTOS
![Page 14: Real-Time Operating Systems for Embedded Computing](https://reader030.vdocument.in/reader030/viewer/2022012919/56814487550346895db11d1b/html5/thumbnails/14.jpg)
A Case Study
On-Chip Multimedia Real-Time OS LSIs such as digital signal processing,
image processing, and protocol processingTwo Major problems:
Overhead of Cyclic Task ExecutionMemory Capacity Limiation
![Page 15: Real-Time Operating Systems for Embedded Computing](https://reader030.vdocument.in/reader030/viewer/2022012919/56814487550346895db11d1b/html5/thumbnails/15.jpg)
Modeling of System LSIs
Core CPU MemoryHOST I/F
I/O
Block #A Block #B Block #C
Application specific hardware unit
![Page 16: Real-Time Operating Systems for Embedded Computing](https://reader030.vdocument.in/reader030/viewer/2022012919/56814487550346895db11d1b/html5/thumbnails/16.jpg)
Requirements of Embedded Software
Requirement Hardware control Scheduling Synchronization Urgent processing Memory capacity
Real-Time OS function
Task Management Multitasking Scheduling New cyclic task
Interrupt Management
Semaphore Management
Very small real time OS
![Page 17: Real-Time Operating Systems for Embedded Computing](https://reader030.vdocument.in/reader030/viewer/2022012919/56814487550346895db11d1b/html5/thumbnails/17.jpg)
On-Chip Multimedia Real-Time OS
Task management
Cyclic task is created and start
Cyclic task is deleted
Dedicated interval time
Cyclic task execution
Resource for task
Allocated
Resource for task
deleted
![Page 18: Real-Time Operating Systems for Embedded Computing](https://reader030.vdocument.in/reader030/viewer/2022012919/56814487550346895db11d1b/html5/thumbnails/18.jpg)
On-Chip Multimedia Real-Time OS
Cyclic task is created and start
Cyclic task is suspended
Cyclic task is resume
Cyclic task is deleted
Resource for task
Not deleted
Resource for task
Allocated
Resource for task
Not allocated
Resource for task
deleted
![Page 19: Real-Time Operating Systems for Embedded Computing](https://reader030.vdocument.in/reader030/viewer/2022012919/56814487550346895db11d1b/html5/thumbnails/19.jpg)
On-Chip Multimedia Real-Time OS
Interrupt ManagementSemaphore management
![Page 20: Real-Time Operating Systems for Embedded Computing](https://reader030.vdocument.in/reader030/viewer/2022012919/56814487550346895db11d1b/html5/thumbnails/20.jpg)
Conclusion
Made a survey of real-time OS for embedded system
Factors which influence the choosing of OS?The requirements of the applicationsThe special features of OSReal- Time constrained
![Page 21: Real-Time Operating Systems for Embedded Computing](https://reader030.vdocument.in/reader030/viewer/2022012919/56814487550346895db11d1b/html5/thumbnails/21.jpg)