OPERATING SYSTEMS 1 龚玲 lgong@sjtu.edu.cn
OPERATING SYSTEMS 龚玲 lgong@sjtu.edu.cn 1
REVIEW o Thread issues ohttp://wenku.baidu.com/course/study/77f1dcccda38376ba flfae94#665ea0c7aa00b52acfc7ca94
REVIEW Thread issues http://wenku.baidu.com/course/study/77f1dcccda38376ba f1fae94#665ea0c7aa00b52acfc7ca94
Chapter 5:CPU Scheduling o Basic Concepts o Scheduling Criteria o Scheduling Algorithms o Real-Time Scheduling o Thread Scheduling o Operating Systems Examples o Java Thread Scheduling o Algorithm Evaluation
Chapter 5: CPU Scheduling Basic Concepts Scheduling Criteria Scheduling Algorithms Real-Time Scheduling Thread Scheduling Operating Systems Examples Java Thread Scheduling Algorithm Evaluation
Goals for today o Basic Concepts o Scheduling Criteria o Scheduling Algorithms
Goals for today Basic Concepts Scheduling Criteria Scheduling Algorithms
Diagram of Process State new admitted interrupt exit terminated ready running 1/O or event completion scheduler dispatch 1/O or event wait waiting
Diagram of Process State
Created Terminated Main Memory Running Ready Blocked Swapped out and waiting Swapped out and blocked Page file/swap space The various process states,displayed in a state diagram,with arrows indicating possible transitions between states-as can be seen,some processes are stored in main memory,and some are stored in secondary (virtual)memory. Reference from http://en.wikipedia.org/wiki/Process_states
The various process states, displayed in a state diagram, with arrows indicating possible transitions between states - as can be seen, some processes are stored in main memory, and some are stored in secondary (virtual) memory. Ready Reference from http://en.wikipedia.org/wiki/Process_states
Process and Thread Scheduling o Process scheduling Long term scheduling Move process to Ready List (RL")after creation (When and in which order?)Decision-making policies to determine the order in which active processes should compete for the use of the CPU(s). o Dispatching o Short term scheduling Select process from Ready List to run The actual binding of a selected process to a CPU,removal from the ready queue,change of status,and loading the processor state
Process and Thread Scheduling Process scheduling Long term scheduling Move process to Ready List (“RL”) after creation (When and in which order?) Decision-making policies to determine the order in which active processes should compete for the use of the CPU(s). Dispatching Short term scheduling Select process from Ready List to run The actual binding of a selected process to a CPU, removal from the ready queue, change of status , and loading the processor state. 7
Basic Concepts o Maximum CPU utilization obtained with multiprogramming o CPU-I/O Burst Cycle-Process execution consists of a cycle of CPU execution and I/O wait o CPU burst distribution
Basic Concepts Maximum CPU utilization obtained with multiprogramming CPU–I/O Burst Cycle – Process execution consists of a cycle of CPU execution and I/O wait CPU burst distribution
Alternating Sequence of CPU And I/O Bursts load store add store CPU burst read from file wait for l/O 1/O burst store increment index CPU burst write to file wait for l/O 1/O burst load store add store CPU burst read from file wait for l/O 1/O burst ●
Alternating Sequence of CPU And I/O Bursts
Histogram of CPU-burst Times 160 140 120 100 030 40 20 0 8 16 24 32 40 burst duration(milliseconds)
Histogram of CPU-burst Times
