1. Fault-Tolerant NoC-based Manycore system: Reconfiguration & Scheduling
ZHANG Jie
CURE

2. Outline
Introduction
Reconfiguration
Scheduling
Summary

3. Introduction

4. Introduction Manycore process
Also known as multicore or chip multiprocessor (CMP)
Integrate numbers of cores on a single die
Architecture for parallel execution
E.g. TILE64 processor, intel 80-core teraflop processor

5. Network-on Chip (NoC)
NoC is generally regarded as the most promising on-chip communication architecture.
Share Bus
Bad Scalability
Point to Point
Hardware Overhead
NoC

6. Hardware is not perfect.
Hard faults/Permanent faults
Manufacturing defects
Wear-out faults, aging effects
Both cores and NoC are fault-prone.
Core-level redundancy, e.g. GeForce 8800 (192-96)
Redundancy

7. Reconfiguration

8. Reconfiguration Hardware failures Hardware designers’ concern:
cannot be predicted.
cause NoC to be irregular and diverse from each other.
Hardware designers’ concern:
Mitigate the performance degradation in the presence of faults with the redundancy
Software designers’ concern:
How to optimize applications under diverse hardware platforms.

9. Solution Virtual Topology: a layer between SW and HW
How to efficiently and effectively choose the VT.

10. Scheduling

11. Scheduling Core scheduling & task scheduling Requirement
Core scheduling assigns the required number of cores to the jobs.
Task scheduling determines the order in which incoming jobs are executed.
Requirement
fast

12. Traditional Solutions
Scheduling Problem:
Given a sequence of jobs which have diverse core requirement.
Minimize the execution time
Solution
Contiguous scheduling: Cores assigned are physically adjacent.
Aim: Let as many active cores as possible
Problem:
Ignore topology asymmetry of NoC
Ignore performance asymmetry of cores

13. Proposed Solution Requirement: fast NoC asymmetry Core asymmetry
Virtual Topology: provide the best platform to OS
Core asymmetry
Basic idea: set weights for each core
High weight for high-performance core
Low weight for low-performance core

14. Summary

15. Summary Reliability and performance should been considered together.
HW should provide both reliable and high-performance platform to OS, while SW should properly adopt it to achieve full performance.