Types of Multiprocessing Operating System
Duration: 6 min
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This educational video provides a comprehensive overview of multiprocessing systems, specifically distinguishing between Symmetric and Asymmetric multiprocessing architectures. The lecture begins by defining Symmetric Multiprocessing (SMP), highlighting that a single operating system instance manages multiple identical processors sharing a common main memory. It emphasizes the peer-to-peer nature of SMP where no boss-worker hierarchy exists. The session then transitions to Asymmetric Multiprocessing, characterized by a master-slave relationship where a single master processor controls the system and assigns tasks to slave processors. Finally, the instructor outlines the advantages, such as increased throughput and reliability, and disadvantages, including complexity and memory requirements, concluding with a brief mathematical note on the screen.
Chapters
0:00 – 2:00 00:00-02:00
The instructor introduces Symmetric Multiprocessing (SMP) using a slide titled 'Multiprocessing can be of two types'. He underlines key phrases like 'single OS instance' and 'identical processors' to emphasize that SMP involves multiple processors controlled by one OS instance connected to a single shared main memory. The diagram illustrates four processors, each with its own cache, connected via a 'Bus or Crossbar Switch' to shared memory and I/O. The instructor stresses that in SMP, all processors are peers with no boss-worker relationship, a concept common in Windows, Mac OS, and Linux. He specifically underlines 'peers' and 'no boss-worker relationship' to reinforce the equal status of processors in this architecture. He also notes that most multi-processing PC motherboards utilize this.
2:00 – 5:00 02:00-05:00
The lecture shifts to Asymmetric Multiprocessing, defined as a master-slave relationship where one processor acts as a master controlling others that behave as slaves. The instructor underlines 'master-slave' and explains that specific tasks, like responding to hardware interrupts or executing kernel-mode code, may be restricted to a particular CPU. The diagram depicts a 'Boss' processor controlling 'Worker' processors, illustrating the boss-worker relationship. He notes that while such restrictions make systems easier to design, they tend to be less efficient than systems where all CPUs are utilized equally. He underlines 'easier to design' and 'less efficient' to contrast the trade-offs. He also mentions that user-mode code may be executed in any combination of processors.
5:00 – 6:27 05:00-06:27
The final section covers the 'Advantage of multiprocessing' and 'Disadvantages'. Advantages listed include Increased Throughput, Economy of Scale, Increased Reliability (fault tolerance), and less battery consumption. The instructor explains that if one processor fails, the system slows down rather than halting, citing an example where ten processors mean a 10% slowdown if one fails. The disadvantages slide lists complexity, context switching overhead, and the need for large main memory. During this segment, the instructor writes '23 x 4 = 92' on the screen, possibly as a side note or calculation example. He also underlines 'Increased Throughput' and 'Increased Reliability'. He mentions that multiprocessing systems can cost less due to shared peripherals.
The video effectively contrasts Symmetric and Asymmetric multiprocessing, moving from architectural definitions to practical implications. It establishes that SMP offers efficiency through peer processors, while Asymmetric offers design simplicity through hierarchy. The final discussion on pros and cons provides a balanced view of why multiprocessing is used despite its added complexity.