os211

  1. Virtual Memory
    Virtual memory is a memory management technique where secondary memory can be used as if it were a part of the main memory. Virtual memory is a very common technique used in the operating systems (OS) of computers.

  2. Differences between Cache Memory and Virtual Memory
    In memory hierarchy, there is an additional level of memory which is Cache. It is high-speed storage and much faster than the main storage. It is much expensive as compared to main storage. So, a relatively small amount of cache is used.

  3. What is non-uniform memory access in industrial controls?
    Non-uniform memory access (NUMA) is a kind of memory architecture that allows a processor faster access to contents of memory than other traditional techniques. In other words, in a NUMA architecture, a processor can access local memory much faster than non-local memory.

  4. Thrashing and Working Sets
    How to deal with thrashing? If a single process is too large for memory, there is nothing the OS can do. That process will simply thrash. If the problem arises because of the sum of several processes:
    • Figure out how much memory each process needs.
    • Change scheduling priorities to run processes in groups that fit comfortably in memory: must shed load.

  5. Page Replacement Algorithm
    In a computer operating system that uses paging for virtual memory management, page replacement algorithms decide which memory pages to page out, sometimes called swap out, or write to disk, when a page of memory needs to be allocated. Page replacement happens when a requested page is not in memory (page fault) and a free page cannot be used to satisfy the allocation, either because there are none, or because the number of free pages is lower than some threshold.

  6. Virtual Address Space
    In computing, a virtual address space (VAS) or address space is the set of ranges of virtual addresses that an operating system makes available to a process. The range of virtual addresses usually starts at a low address and can extend to the highest address allowed by the computer’s instruction set architecture and supported by the operating system’s pointer size implementation, which can be 4 bytes for 32-bit or 8 bytes for 64-bit OS versions.

  7. Copy-on-Write Semantics
    Copy-On-Write, abbreviately referred to as CoW suggests deferring the copy process until the first modification. A resource is usually copied when we do not want the changes made in either to be visible to the other.

  8. Will ‘Htop’ Replace Default ‘Top’ Monitoring Tool in Linux?
    Top is a traditional command-line tool for monitoring real-time processes in a Unix/Linux systems, it’s comes preinstalled on most if not all Linux distributions and shows a useful summary of system information including uptime, total number of processes (and number of: running, sleeping, stopped and zombie processes), CPU and RAM usage, and a list of processes or threads currently being managed by the kernel.

9 What Is Kernel Memory in Task Manager?
The kernel memory in the task manager is a part of the total memory available in a computer that is blocked off for the operating system’s processes. The total memory consists of the RAM (random-access memory) and the virtual memory.

10 Memory-mapped IO vs Port-mapped IO
Microprocessors normally use two methods to connect external devices: memory mapped or port mapped I/O. However, as far as the peripheral is concerned, both methods are really identical.