About Multiprocessor Scheduling

Bundet
Bundet
Nov 1 · 5 min read

A multiprocessor requires a more complicated scheduling because it has many possibilities that are tried unlike in a processor processor. But now we only focus on homogeneous (same) processors according to their respective functions. And also we can use the available processor to run the process in the queue.

Multiprocessor Scheduling

1. Multiple Processor Scheduling

Our discussion to date has been the issue of scheduling CPUs on a single processor. If multiple processors exist. Scheduling is becoming more complex and many possibilities have been tried and we have seen with scheduling one processor, there is no best solution. At this time, we only briefly discuss the timing of multiprocessors on the condition that the processors are identical.

If there are several identical processors available, load sharing will occur. We can provide a separate queue for each processor. In this case, however, one processor can become idle with an empty queue while the other is very busy. To anticipate this we use the usual ready queue. All processes go to one queue and are scheduled for a processor that can be used.

In the scheme, one of the scheduling will be used. One way to use symmetric multiprocessing (SMP). Where each processor schedules itself. Each processor checks the raedy queue and selects the process to be executed.

Some systems bring structure one step forward, by bringing all scheduling decisions, I / O processing, and other system activities to be handled by one processor who is in charge of the master processor. The other processor executes only user code called asymmetric multiprosessing much easier.

2. Real Time Scheduling

In this chapter, we will describe the scheduling facilities needed to support real time computing with the help of a computer system.

There are two types of real time computing: a hard real time system is needed to complete critical tasks with guaranteed time. In general, a process is sent with a statement of the amount of time needed to complete or execute I / O. Then the scheduler can guarantee the process is complete or reject the request because it is not possible. Therefore every operation must be guaranteed with maximum time.

Soft real time computing is less restrictive. It requires that a critical process accepts priority from others. Although adding soft real time functions to the time sharing system might result in inadequate sharing of resources and result in longer delays, or perhaps cancellation of certain processes, the result is a general purpose system that can support multimedia, high-speed graphics, and variety of tasks. which is unacceptable in an environment that does not support soft real time computing.

Implementing soft real time functions requires careful design and aspects related to the operating system. First, the system must have a scheduling priority, and the real time process must not exceed time, even though non-real time priorities can occur. Second, dispatch latency must be smaller. The smaller the latency, the faster the real time executing process.

To keep dispatch low. We need the system call to preemptible. There are several ways to achieve this goal. One to enter preemption points for a long duration of the system call, which checks whether the main priority needs to be executed. If one has, then context takes over; when the high priority process is complete, the interrupted process continues with the system call. Premption points can be replaced only in safe locations in the kernel — only the kernel structure cannot be modified even with preemption points, dispatch latency can be large, because in practice to add several preemption points to the kernel.

Another method for dealing with preemption is to make all kernels preemptible. Because proper operation can be guaranteed, all kernel data structures are protected. With this method, the kernel can always be preemptible, because all kernels can be updated protected.

What can be protected if the first priority needs to be read or modified which can be needed by others, low priority? High priority must wait to wait for low priority.

The conflict phase of dispatch latency has two components:

  1. Preemption of all processes running in the kernel.
  2. Take off the low priority for the high priority.

3. Thread Scheduling

In Section 2.5, we introduce threads to the process model, it allows a process to have control over multiple threads. We further distinguish between user-level and kernel-level threads. User level threads are managed by the thread library. To run on the CPU, user level threads are mapped with thread level kernel associations, although this mapping might be indirect and use lightweight.

References

This book is presented from the Joint Working Group 21–28 IKI-20230 Even Semester 2002/2003, by the Joint Working Group 21–28 IKI-20230 Even Semester 2002/2003, for anyone who wants to learn the Operating System. The book’s drafting team is as follows:

Group 21 (Coordinator)

Dhani Yuliarso, Fernan, Hanny Faristin, Melanie Tedja, Paramanandana DM, Widya Yuwanda.

Group 22 (Chapter 1)

Budiono Wibowo, Agus Setiawan, Baya UHS, Budi A. Azis Dede Junaedi, Heriyanto, Muhammad Rusdi.

Group 23 (Chapter 2)

Indra Agung, Ali Khumaidi, Arifullah, Baihaki AS, Christian KF Daeli, Eries Nugroho, Eko Seno P., Habrar, Haris Sahlan.

Group 24 (Chapter 3)

Adzan Wahyu Jatmiko, Agung Pratomo, Dedy Kurniawan, Samiaji Adisasmito, Zidni Agni.

Group 25 (Chapter 4)

Nasrullah, Amy S. Indrasari, Ihsan Wahyu, Inge Evita Putri, Muhammad Faizal Ardhi, Muhammad Zaki Rahman, N. Rifka N. Liputo, Nelly, Nur Indah, R. Ayu P., Sita AR

Group 26 (Chapter 5)

Rakhmad Azhari, Adhe Aries, Adityo Pratomo, Aldiantoro Nugroho, Framadhan A., Pelangi, Satrio Baskoro Y.

Group 27 (Chapter 6)

Teuku Amir FK, Alex Hendra Nilam, Anggraini W., Ardini Ridhatillah, R. Ferdy Ferdian, Ripta Ramelan, Suluh Legowo, Zulkifli.

Group 28 (Chapter 7)

Operating System: IKI-20230 Lecture Material by the Joint Working Group 21–28 IKI-20230 Even Semester 2002/2003

$ Revision: 1.3.0.0 $ Edition

Published September 30, 2003

Copyright (2003) © 2003 by Work Group Affiliation 21–28 IKI-20230 Evening Semester 2002/2003.

Please copy, distribute and / or, modify parts of the document — $ Revision: 1.3.0.0 $ — — composed by the Working Group 21–228 IKI-20230 Even Semester 2002/2003, in accordance with the provisions of the “GNU Free Documentation License version 1.1 “or later version of the FSF (Free Software Foundation); without the “Invariant” section, without the “Front-Cover” text, and without the “Back-Cover” text. Appendix A contains a complete copy of the license. This provision does NOT apply to parts and / or quotations not composed by Joint Working Groups 21–28 IKI-20230 Even Semester 2002/2003.

Revision Note

Revisi 1.3 30–09–2003 Revised by: RMS46

This revision was edited by Rahmat M. Samik-Ibrahim: continuing to improve layout and indexing.

Revisi 1.2 17–09–2003 Revised by: RMS46

This revision was edited by Rahmat M. Samik-Ibrahim: continuing improvements.

Revisi 1.1 01–09–2003 Revised by: RMS46

This revision was edited by Rahmat M. Samik-Ibrahim: to improve the structure of SGML, without too much changing the contents of the book.

Revisi 1.0 27–05–2003 Revised by: RMS46

Recompile, and do a little tidying.

Revision 0.21.4 05–05–2003 Revised by: Group 21 File tidying and adding entities.

Revision 0.21.3 29–04–2003 Revised by: Group 21 Changes by perfecting the file name.

Revision 0.21.2 24–04–2003 Revised by: Group 21

Change the Preface.

Revision 0.21.1 21–04–2003 Revised by: Group 21

Add Bibliography and Index.

Revision 0.21.0 26–03–2003 Revised by: Group 21 Initiating the Operating System lecture group work.

Christiono H, Arief Purnama LK, Arman Rahmanto, Fajar, Muhammad Ichsan, Rama P. Tardan, Unedo Sanro Simon.

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