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...
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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