Real time system in Multicore/Multiprocessor system

BITS PilaniHyderabad Campus

Real Time Scheduling in Multi-core systems

ByMayank Garg

2013H140040H

UNDER THE SUPERVISION OFK C S MURTHI

DEPARTMENT OF COMPUTER ENGINEERING

BITS Pilani, Hyderabad Campus

CONTENTS

Mayank Garg Slide 2

Partitioned Fixed-priority Real-time Scheduling Based on Dependent Task-Split On Multicore Platform

Mixed-Criticality Real-Time Scheduling for Multicore System

Task Scheduling of Real-time Systems on Multi-Core Architectures

HISTORY OF E-NOSE

A Shared Cache-aware Hybrid Real-time Scheduling on Multicore Platform with Hierarchical Cache

CONCLUSIONS

RESEARCH STUDY

A User space Library for Multicore Real-Time Scheduling

A Simple Power-Aware Scheduling for Multicore Systems when Running Real-Time Applications

REFERENCES

BITS Pilani, Hyderabad Campus

Real Time Scheduling Need of Multicore systems Global Scheduling: Task can execute on any processor at any

time.

Partitioned Scheduling: Tasks are statically allocated to

processors and migration of tasks among processors is not allowed. Single core System Multi core Systems

Introduction

Mayank Garg Slide 3

BITS Pilani, Hyderabad CampusMayank Garg

Throughput Latency

Turnaround Time Response time

FairnessWaiting Time

Slide 4

BITS Pilani, Hyderabad CampusMayank Garg

To scheduling the tasks with precedence constraints,

he partition them into the independent tasks first.

The precedence relationship is denoted by the task

graph which is directed and no-loop.

Slide 5

Task Scheduling of Real-time Systems on Multi-Core Architectures

BITS Pilani, Hyderabad CampusMayank Garg

We use a two-level hierarchical scheduling approach in our mixed criticality architecture. Our architecture assumes a similar five level classification.

If the job completes before its budget is exhausted, it becomes a ghost job, ghost jobs are viewed identically to normal jobs a similar five-level classification.

Slide 6

Mixed-Criticality Real-Time Scheduling for Multicore System

BITS Pilani, Hyderabad CampusMayank Garg

This design methodology comprises two stages: tasks dispatch and (sub) tasks assignment.

For tasks dispatch, an efficient algorithm B-tree Dependent Tasks dispatch (BDTD) is proposed aiming at dispatching tasks on individual cores and converting a set of dependent tasks into a series of sequential subtasks, there upon the interrelated sub-tasks path is obtained as well as synthetic deadlines.

Tasks assignment takes advantage of algorithm B-tree Dependent Task Split (BDTS) to solve how dependent tasks decompose to derive a high utilization.

Slide 7

Partitioned Fixed-priority Real-time Scheduling Based on Dependent Task-Split On

Multicore Platform

BITS Pilani, Hyderabad CampusMayank Garg Slide 8

Partitioned Fixed-priority Real-time Scheduling Based on Dependent Task-Split On Multicore

Platform (cont.)

BITS Pilani, Hyderabad CampusMayank Garg

The main idea of the improved algorithm:

First, assigning each task a priority according to their deadline.

If no pre-emptive task, original task keep running until finished. When task finished, checking whether there is an urgent task.

if there is scheduled it in the next schedule, if no urgent tasks, dispatching the task on the head of the ready queue.

Slide 9

A Shared Cache-aware Hybrid Real-time Scheduling on Multicore Platform with

Hierarchical Cache

BITS Pilani, Hyderabad CampusMayank Garg

The scheduler pursues to minimize the number of transitions by increasing or decreasing the voltage and frequency of all the cores at the same time.

Frequency increases when it is required to satisfy the time requirements of real-time tasks.

On the other hand, when a task finishes its execution, if its computation time can be guaranteed, the frequency is reduced.

Slide 10

A Simple Power-Aware Scheduling for Multicore Systems when Running Real-

Time Applications

BITS Pilani, Hyderabad CampusMayank Garg Slide 11

A Shared Cache-aware Hybrid Real-time Scheduling on Multicore Platform with Hierarchical Cache (cont.)

BITS Pilani, Hyderabad CampusMayank Garg

He is trying to demonstrate by empirical process that a user space library can support the class of resource allocation, with latencies and overheads that are sufficiently small as to make his library relevant for a subset of future real-world real time applications.

While his library is currently a proof-of concept research effort.

Slide 12

A User space Library for Multicore Real-Time Scheduling

BITS Pilani, Hyderabad CampusMayank Garg Slide 13

A User space Library for Multicore Real-Time Scheduling (Cont.)

Schematic of overall architecture. This application is scheduled across one cluster of four processors. “w.t.” stands for “worker thread.” Note how worker threads perform the role of “virtual CPUs” for real-time tasks.

BITS Pilani, Hyderabad CampusMayank Garg Slide 14

I have studied many research perspective and technologies for getting a better understanding about this topic.

I have analysed that many of these are good scheduling algorithm in some constraint but they are fit for overall design. So I like to find an algorithm which can give almost optimal output for overall system.

My research proposal is to find an optimal scheduling algorithm for overall design of Multi-core Real Time System and implement it.

BITS Pilani, Hyderabad Campus

Thank You!!

Mayank GargSlide 15

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