cpre 458 558 real time systems
Download
Skip this Video
Download Presentation
CprE 458/558: Real-Time Systems

Loading in 2 Seconds...

play fullscreen
1 / 8

CprE 458 - PowerPoint PPT Presentation


  • 166 Views
  • Uploaded on

CprE 458/558: Real-Time Systems. Resource Reclaiming. Dynamic Scheduling Model. Schedulability checking (on-line) - by the scheduler Schedule construction (on-line) - by the scheduler Dispatching, Task execution, & Resource reclaiming - by the processors. Resource Reclaiming.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'CprE 458' - rona


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
cpre 458 558 real time systems

CprE 458/558: Real-Time Systems

Resource Reclaiming

CprE 458/558: Real-Time Systems (G. Manimaran)

dynamic scheduling model
Dynamic Scheduling Model
  • Schedulability checking (on-line) - by the scheduler
  • Schedule construction (on-line) - by the scheduler
  • Dispatching, Task execution, & Resource reclaiming - by the processors

CprE 458/558: Real-Time Systems (G. Manimaran)

resource reclaiming
Resource Reclaiming

Resource reclaiming refers to the problem of utilizing resources left unused by a task when:

  • it executes less than its worst case computation time. The actual computation time of a task can be less than its worst case computation time due to
    • data dependent loops and conditional statements in the task code.
    • architectural features of system such as cache hits and branch predictions.

CprE 458/558: Real-Time Systems (G. Manimaran)

resource reclaiming contd
Resource Reclaiming (Contd.)
  • it is deleted from the current schedule. Deletion of a task takes place when extra tasks are initially scheduled to account for fault tolerance.
  • it is dropped to make room for more critical tasks.

CprE 458/558: Real-Time Systems (G. Manimaran)

properties of reclaiming algorithms
Properties of Reclaiming Algorithms
  • Correctness: No run-time anomaly.
  • Inexpensive: The overhead cost of a resource reclaiming should be very low compared to tasks’ computation times.
  • Bounded complexity: The complexity of a resource reclaiming algorithm should be independent of the number of tasks in the schedule.
  • Effectiveness: A resource reclaiming algorithm is effective only when its performance is better than that of when no resource reclaiming is used.

CprE 458/558: Real-Time Systems (G. Manimaran)

resource reclaiming algorithms
Resource Reclaiming Algorithms
  • Basic Algorithm: If there are “simultaneous holes,” in the schedule, it can be reclaimed.
  • Early Start Algorithm: reclaims resources with the condition that if two tasks are non-overlapping in the pre-run schedule, then they should not overlap in the post-run schedule.
  • RV Algorithm: Based on a data structure, called Restriction Vector.
  • RV with Migration: Allows task migration from one processor to another.

CprE 458/558: Real-Time Systems (G. Manimaran)

reclaiming example
Reclaiming -- Example

CprE 458/558: Real-Time Systems (G. Manimaran)

reclaiming example contd
Reclaiming – Example (contd.)

CprE 458/558: Real-Time Systems (G. Manimaran)

ad