1. Senthil
June 26, 2014
Parallel Computing

2. Background
“We all have done, are doing and will do
Parallel Computing in our daily lives”

3. Examples
 Studying for an exam
 Multiple subjects in a semester
 Working together as a team – Towards a
common goal
 Our Brain – All in all
“No super computer has reached the
processing capabilities of a human brain”

4. Today…
“We will try to bridge the Tech and Non Tech
understanding of Parallel Computing”
 Tech – Java
 Non Tech – Self and Team Work

5. Need
 Faster processing
 Save power
 Efficient utilization of resources

6. Processing
 Serial Run – One after the other – Semester
Exam – One exam a day
 Parallel Run
 Threading – Reading a book
 Executors – Working as a team
 Fork Join – Working as an efficient team

7. Threading
 Non Tech Example – Reading a book or Studying
for an exam

8. Threading
 See
 Read
 Underline important points
 Understand
 Remember
“Similarly, a computer process can spawn
threads to compute a problem in parallel”

9. Executors – Java 6
 Single Core vs. Multi Core
 How to use multi core
 Thread Pooling
“Working together as a team”

10. Fork Join – Java 7
 Divide and Conquer
 Use multiple cores
 Special Algorithm – WORK STEALING
“Working as an efficient team”

11. Work Stealing
 Steal the work from cores that are busy
 Full utilization of CPU
“If you are free,
share the work load of your team mates”

12. Practical
 100 tasks need to be run on a Quad Core machine
 Following ways
 Serial
 Parallel – Executors [4 & 16 threads]
 Parallel – Fork Join
 Observe the CPU Chart
Note
 Practical code - Parallel.zip available
mfinfiles02/Public_Engineering_India/_Device_Team/Senthil/Parallel.zip
 Study jDevSim code [jDevSim, jAppDownload, jGcmServer] –
http://mfinsvn/repo-mirror/devices/trunk/JavaDeviceSimulator

13. CPU Chart – Serial
 122.777 seconds
 10 to 15% CPU Utilization

14. CPU Chart – Executors – 4 Threads
 36.624 seconds
 ~50+% CPU Utilization

15. CPU Chart – Executors – 16 Threads
 16.842 seconds
 Almost 100%

16. CPU Chart – Fork Join
 15.889 seconds
 100% – Complete Utilization

17. Thank You