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Install K8S on VM and spring boot integration.

Installation Environment Vmware Workstation pro  It is recommended to use the  snapshot  to store the state of each installation stage to avoid installation failures and causing the installation to start from scratch. Ubuntu 22.04 windows 11 Hardware settings  create 3 VM: 4 cores and 4G memory and 100G capacity Before installing K8s (All use the root user) set host: 192.168.47.135 master 192.168.47.131 node1 192.168.47.132 node2 set root ssh connection: sudo su - echo "PermitRootLogin yes" >> /etc/ssh/sshd_config systemctl restart sshd sudo passwd ssh-keygen for i in {master,node1,node2}; do  ssh-copy-id root@$i; done set Ipvs and conf  create conf file: for i in {master,node1,node2}; do ssh root@$i 'cat << EOF > /etc/modules-load.d/containerd.conf overlay br_netfilter EOF'; done execute conf: for i in {master,node1,node2}; do ssh root@$i 'modprobe overlay;modprobe br_netfilter;'; done create 99-kubernetes-cri.conf file: for i in {maste...
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Virtual memory

Virtual memory

Separation of user logical memory from physical memory.

  • To run an extremely large process.
    • Logical address space can be much larger than physical address space.
  • To increase CPU/resource utilization.
    • A higher degree of multiprogramming degree.
  • To simplify programming tasks.
    • A free programmer from memory limitation.
  • To run programs faster.
    • Less I/O would be needed to load or swap.

Process & virtual memory

  • Demand paging: only bring in the page containing the first instruction.
  • Copy-on-write: the parent and the child process share the same frames initially, and frame-copy. when a page is written.
    • Allow both the parent and the child process to share the same frames in memory.
    • If either process modifies a frame, only then a frame is copied.
    • COW allows efficient process creation(e.g., fork()).
    • Free frames are allocated from a pool of zeroed-out frames(for security reasons).
      • The content of the frame is erased to 0
  • Memory-Mapped File: map a file into the virtual address space to bypass file system calls(e.g., read(), write())

Page Replacement Concept

  • When a page fault occurs with no free frame
    • Swap out a process, freeing all its frames, or
    • Page replacement: find one currently used and free it
      • Use dirty bit to reduce the overhead of page transfers-only modified pages are written to disk
  • Solve two major problems for demand paging
    • Frame-allocation algorithm:
      • Determine how many frames are to be allocated to a process.
    • Page-replacement algorithm:
      • Select which frame to be replaced
      • Goal: lowest page-fault rate
      • Evolution: running against a string of memory references (reference string) and computing the number of page faults
      • Replacement algorithms:
        • FIFO algorithm.
        • Optimal(Belady) algorithm.
        • LRU algorithm.
      • Counting algorithms:
        • LFU Algorithm(least frequently used).
        • MGU Algorithm(most frequently used).

Thrashing

  • If a process does not have "enough" frames.
    • The process does not have #frames it needs to support pages in active use. -> very high paging activity
  • A process is thrashing if it is spending more time.
  • To prevent thrashing, one must provide enough frames for each process:
    • Working-set model, page-fault frequency
reference:
https://www.amazon.com/-/zh_TW/Operating-System-Concepts-Abraham-Silberschatz/dp/1119800366/ref=sr_1_1?keywords=Operating-System-Concepts&qid=1669538704&s=books&sr=1-1

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Install K8S on VM and spring boot integration.

Installation Environment Vmware Workstation pro  It is recommended to use the  snapshot  to store the state of each installation stage to avoid installation failures and causing the installation to start from scratch. Ubuntu 22.04 windows 11 Hardware settings  create 3 VM: 4 cores and 4G memory and 100G capacity Before installing K8s (All use the root user) set host: 192.168.47.135 master 192.168.47.131 node1 192.168.47.132 node2 set root ssh connection: sudo su - echo "PermitRootLogin yes" >> /etc/ssh/sshd_config systemctl restart sshd sudo passwd ssh-keygen for i in {master,node1,node2}; do  ssh-copy-id root@$i; done set Ipvs and conf  create conf file: for i in {master,node1,node2}; do ssh root@$i 'cat << EOF > /etc/modules-load.d/containerd.conf overlay br_netfilter EOF'; done execute conf: for i in {master,node1,node2}; do ssh root@$i 'modprobe overlay;modprobe br_netfilter;'; done create 99-kubernetes-cri.conf file: for i in {maste...
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SOLID

SOLID is the fundamental and core principle of OOP. Single-Responsibility Principle High cohesion: A module preferably has only one business logic. Low coupling:   The different modules work independently and are connected by simple protocols to minimize side effects. Open-Closed Principle Open for extension:  It is easy to extend new functions with existing code. Close for modification:  Do not modify existing classes to ensure stable functions. Liskov-Substitution Principle A superclass should be replaceable with objects of its subclasses without breaking the application. Interface-Segregation Principle Clients only depend on the interfaces they need, don't use the "big" interface to contain everything. Dependence-Inversion Principle The program should depend upon abstractions, not concretions. reference: https://en.wikipedia.org/wiki/SOLID https://blog.knoldus.com/what-is-liskov-substitution-principle-lsp-with-real-world-examples/ https://github.com/hollischuang/toBeTo...
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Cpu scheduling

Table of contents [ hide ] Basic concept The idea of multiprogramming: Keep several processes in memory. Every time one process has to wait, another process takes over the use of the CPU. CPU-I/O burst cycle: Process execution consists of a cycle of CPU execution and I/O wait(i.e., CPU burst and I/O burst). Generally, there is a large number of short CPU bursts and a small number of long CPU bursts An I/O-bound program would typically have many very short CPU bursts. A CPU-bound program might have a few long CPU bursts. CPU scheduler Select from the ready queue to execute(I.e allocates an APU for the selected process) CPU scheduling  decision may take place when a process: Switch from running to waiting state. Switch from running to ready state. Switch from waiting to ready. Terminates. Non-preemptive scheduling: Scheduling under 1 and 4(no choice in terms of scheduling). The process keeps the CPU until it is terminated or switched to the waiting state. Preemptive schedul...
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