real-time computing and the evolution of embedded system...
TRANSCRIPT
![Page 1: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/1.jpg)
Real-Time Computing and the Evolution of Embedded System Designs
Tei-Wei Kuo (Award Recipient), Jian-Jia Chen, Yuan-Hao Chang,
and Pi-Cheng Hsiu
![Page 2: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/2.jpg)
Thank you the Real-Time Systems Community for treating me like a family member!
Unified Memory
2001
1994
2011
2015
2000
1994
2017
San Anotnio, TX1991
Paris, 2017
![Page 3: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/3.jpg)
Real-Time Computing and Embedded Systems
The field of real-time computing is rich in research problems!
More specific in their applicationsMore drastic for their failures
An embedded system is a programmed controlling and operating system with a dedicated function within a larger mechanical or electrical system, often with real-time computing constraints.(Wikipedia)
Tei-Wei Kuo, NTU 3
Real-Time Computing
Computing
![Page 4: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/4.jpg)
Real-Time ComputingSystem Correctness:
Logical Correctness (“the results are correct”)Temporal Correctness (“the results are delivered in/on time")
High reactivity and high dependability are more important than the average performanceMany Results in Real-Time Computing:
Least Upper Bound of Utilization FactorSynchronization and Priority CeilingMore Flexible Task Models, e.g., Multi-Frame Tasks
2019/1/10 Tei-Wei Kuo, NTU 4
![Page 5: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/5.jpg)
REAL-TIME COMPUTING
Timing correctness is the key factor to justify whether the system is safe or not. For hard real-time systems, since “any deadline miss can jeopardize the entire system,” it is not allowed to have any deadline miss.
2019/1/10 Tei-Wei Kuo, NTU 5
![Page 6: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/6.jpg)
Execution Time Depends uponThe input, determining which path is takenThe state of the hardware platform:
Due to caches, pipelining, speculation, etc.Interference from the environment:
External interference as seen from the analyzed task on shared buses, caches, memory
Figures from Jan Reineke and Reinhard Wilhem
![Page 7: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/7.jpg)
Worst-Case Execution Time (WCET)Fundamental Research in Real-Time Systems
Active research topic ever since scheduling is explored!Rich Literature in Uniprocessor Systems Commercial Tools, Industrial Case Studies, etc.
Significant Influence over Multicore Systems:Popular Topic Regularly Being Seen as Sessions in Real-Time Conferences Significant Impacts on the Advance in Using Multicore Platforms in Real-Time ComputingRadojkovic et al. (ACM TACO, 2012) on Intel Atom and Intel Core 2 Quad: Up to 14x Slow-Down, Due to Interference on Shared L2 Cache and Memory Controller
2019/1/10 Tei-Wei Kuo, NTU 7
![Page 8: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/8.jpg)
Energy-Efficiency versus Exec Time
2019/1/10 Tei-Wei Kuo, NTU 8
Energy minimization while satisfying the real-time constraints• Active research topics since 2000
Thermal behavior analysis under the real-time constraints• Active research since 2005
In both cases, time is the major constraint
![Page 9: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/9.jpg)
How about Soft Real-Time ComputingRare deadline misses are often acceptable!
Industrial safety standards ~ failures under certain probabilityIEC-61508: Safety Standard for ElectronicsISO-26262: Safety Standard for Automotive Systems
Safe Upper BoundMixed of Hard and Soft Real-Time Tasks: Reservation!
Guaranteed Isolations for Hard Real-Time Tasks Proved Progressiveness for Soft Real-Time TasksFixed-Priority Servers: Polling Server, Periodic Server, Sporadic Server, Deferrable Server, etc.Dynamic-Priority Servers: Total bandwidth server (TBS), Constant bandwidth server (CBS), Proportional Share (PS), etc.
2019/1/10 Tei-Wei Kuo, NTU 9
![Page 10: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/10.jpg)
EMBEDDED SYSTEM DESIGNS
In contrast to real-time computing with time as the key factor, “time” becomes a feature in embedded system designs.
2019/1/10 Tei-Wei Kuo, NTU 10
![Page 11: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/11.jpg)
Computing with Human
2019/1/10 Tei-Wei Kuo, NTU 11
User-Centric Resource Support over Embedded Systems
User Interactivities
Perceived and Unperceived Activities over Embedded Systems
User Attention
Human Perception User Perception over Display, Sound,
and More
![Page 12: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/12.jpg)
Paradigm Shift in Computing
2019/1/10 Tei-W`i Kuo, NTU 12
• User Behavior (Diversity)• Application Semantics (Variety)
• Device Features (Distinctivity)
![Page 13: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/13.jpg)
User-Centric Task SchedulingPerformance Metrics
Energy Efficiency User Experience (a variant of “time”)
Needs to Resource ReservationRequire ways to reserve computing resource to applications in a way “proportionally” to user attentionApplications must be executed and scheduled to improve energy efficiency and user experience
2019/1/10 13P.-C. Hsiu, P.-H. Tseng, W.-M. Chen, C.-C. Pan, and T.-W. Kuo, "User-Centric Scheduling and Governing on Mobile Devices with big.LITTLE Processors," ACM Transactions on Embedded Computing Systems, 15(1): 17:1-17:22, Jan. 2016.
![Page 14: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/14.jpg)
Content-Aware Resource AllocationIncreasingly high resolution and frame rate
Not always with improved perceptual quality Complementary energy savings over DVFS by reducing the GPU workloads
Dynamic resolution scaling (w.r.t viewing distance or scrolling speed)Dynamic frame rate scaling (redundant frames)
Content-aware resource allocationThe time required to render a frame depends on the qualify of contents perceived by the userThe deadline in rendering a frame depends on the frame rate required the userHow to schedule tasks with dynamically adjustable execution times and deadlines?
2019/1/10 14
Dynamic Resolution Scaling
Dynamic frame rate scaling
H.-Y. Lin, C.-C. Hung, P.-C. Hsiu, and T.-W. Kuo, "Duet: An OLED & GPU Co-management Scheme for Dynamic Resolution Adaptation", IEEE/ACM Design Automation Conference (DAC), pp. 126:1-126:6, June 2018.
![Page 15: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/15.jpg)
Attention-Based Resource AllocationBackground activities imperceptibly drains batteries
Repeating Interval: static (periodic) or dynamic (sporadic)Execution Windows: within which to execute an activity (deadline)
Activity alignmentExample: A1 (perceptible HW) and A3 (imperceptible HW) have overlapped execution windows, while A2 and A3 require the same imperceptible HWObservation: HW similarity reflects the degree of energy savings, while time similarity reflects the impact on user perception
2019/1/10 15C.-H. Kao, S.-W. Cheng, and P.-C. Hsiu, "Similarity-Based Wakeup Management for Mobile Systems in Connected Standby," IEEE/ACM Design Automation Conference (DAC), pages 50:1-50:6, June 2016.
Native activity alignment Similarity-based activity alignment
![Page 16: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/16.jpg)
Huge Driving Forces
More than Moore
162019/1/10
Big Data
Tei-Wei Kuo, NTU
![Page 17: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/17.jpg)
Challenges in Computing
2019/1/10 Tei-Wei Kuo, NTU 17
AI ChipsCPU GPU
Main Memory
Storage
CloudStorage
![Page 18: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/18.jpg)
Ways to Break Memory Boundaries
Apps
Kernel System Models
File Systems
Storage Systems
Hardware/Chips
2019/1/10 Tei-Wei Kuo, NTU 18
PerformanceThe gaps of memories is closer than ever.
Capacity They all grow at paces faster than Moore’s Law.
HW/SW Boundaries are blurring or shifting.
![Page 19: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/19.jpg)
Tremendous Performance Gap between the Main Memory and StorageHuge Barrier to Move Data from the Memory to Computing Units
Innovation to Reshape Storage and Computing Markets
2019/1/1019
Long-Tail Big Data
Huge Addressing Space
…Persistent…
Process-in-Memory
Unified Memory
![Page 20: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/20.jpg)
Between Main Memory and Storage
20
Memory Devices Storage Devices
User SpaceProcess 1
…
Process 2
Process nDevice Driver
Kernel Space
Virtual Memory File System
Applications Operating System
SoftwareHardware
Integrated Memory Devices (Pure PCM)
Bing-Jing Chang, Yuan-Hao Chang, Hung-Sheng Chang, Tei-Wei Kuo, and Hsiang-Pang Li, 2014, “A PCM Translation Layer for Integrated Memory and Storage Management,” ACM/IEEE International Conference on Hardware/Software Codesign and System Synthesis (CODES+ISSS), New Delhi, India, Oct 12-17, 2014.2019/1/10
Big Data to Cross the Tremendous Gap between the Main Memory and Storage
Long-Tail Big Data
![Page 21: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/21.jpg)
Caching Again: WCET Issue Only?
21C.-F. Wu, M.-C. Yang, Y.-H. Chang, and T.-W. Kuo, “Hot-Spot Suppression for Resource-Constrained Image Recognition Devices with Non-Volatile Memory,” ACM EMSOFT 2018.
Another Dimension in DesignsEnduranceRead/write asymmetry of NVM
Existing caching algorithms considers performance. The caching algorithms for NVM-based systems need to consider read/write asymmetry and endurance issues.
![Page 22: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/22.jpg)
Huge Barrier to Move Data from the Memory to Computing Units
Scalability of Existing AI Solutions?Machine learning requires high memory bandwidth
2019/1/10 Tei-Wei Kuo, NTU 22
High Bandwidth Memory: The Great Awakening of AI, 2018
![Page 23: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/23.jpg)
Process-in-Memory (PIM) to resolve the memory bandwidth issue.Analog variation error caused by programming variation of crossbar memories
Huge Barrier to Move Data from the Memory to Computing Units
2019/1/10 Tei-Wei Kuo, NTU 23
L. Song et al., “Pipelayer: A pipelined reram-based accelerator for deep learning,” HPCA, 2017.
![Page 24: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/24.jpg)
Design issues of data placement and data flow with input/output buffers in PIM.Algorithm modification for workload partition between CPU/GPU and crossbar PIM memory.Algorithm modification to fit in the special characteristic of PIM.
Huge Barrier to Move Data from the Memory to Computing Units
2019/1/10 24Systolic architecture
![Page 25: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/25.jpg)
RETHINKING REAL-TIME COMPUTING WITH
EMBEDDED SYSTEM EVOLUTION
The advances in mobile systems, memory innovations, and use cases have inspired the evolution of embedded system designs and insights to solutions regarding how systems should be restructured and how computing should be done.
2019/1/10 Tei-Wei Kuo, NTU 25
![Page 26: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/26.jpg)
The Internet-of-Thing EraUnstable Energy SourcesNormally-Off Computing
26
Volatile processor
Roll back
Progress
Failure Resume
2019/1/10 Tei-Wei Kuo, NTU
0
50Volatile Processor
ONOFF
Program Progress(%
)
Intermittent executionIntermittent Computing!
![Page 27: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/27.jpg)
Emerging of Non-Volatile Computing/ Memory Devices
27
Performance Metrics: maxspan vs. forward progress Schedulability tests with power failure possibility
Data Integrity Concurrency Control? Checkpointing? Performance Gap of DRAM and non-volatile memory? Asymmetry in Reads/Writes? Task Models in Computing?
Progress
Battery-less mobile phone
Battery-less wearable
2019/1/10 Tei-Wei Kuo, NTU
![Page 28: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/28.jpg)
Boundary Breaking between Computing Units and Memory
28
Advances in manufacturing and devices presents huge performance gaps between traditional system layers.Do we need new task models in computing and scheduling/analysis methodologies?
2019/1/10 Tei-Wei Kuo, NTU
Neurons
Synapses
Chemical Nerve Pulse
![Page 29: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/29.jpg)
OUR PERSPECTIVES
Although many successful stories can be told to designembedded systems with technology developed in real-time systems, some limitation of our research efforts in real-time systems is foreseen and must be further exploited in designing advance embedded systems.
2019/1/10 Tei-Wei Kuo, NTU 29
![Page 30: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/30.jpg)
Successful Stories and LimitationMany Successful Results and Applications
Fixed-priority schedulers in almost every RTOSEDF in some RTOSesPIP and PCP as part of POSIXThe application of real-time technology in control area network (CAN)WCET analyzer adopted in the industry
However…Computing systems are getting more and more complexDesigning only for the worst case might become a design bottleneck and only applicable for highly reliable systems.The industry seems adopting only a small portion of our work….
2019/1/10 Tei-Wei Kuo, NTU 30
![Page 31: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/31.jpg)
Then…
Huge tsunami of computer system revolution is coming!
2019/1/10 Tei-Wei Kuo, NTU 31
Cyber
PhysicalIntelligence
Science
Engineering
![Page 32: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/32.jpg)
![Page 33: Real-Time Computing and the Evolution of Embedded System ...2018.rtss.org/wp-content/uploads/2018/09/TCRTSAwardPresentation… · The advances in mobile systems, memory innovations,](https://reader035.vdocuments.net/reader035/viewer/2022081611/5f02cd957e708231d4061683/html5/thumbnails/33.jpg)
謝謝! Xièxie!Thank You!