Os Services for Ensuring Efficiency: Systems with multiple users can gain efficiency bysharing the computer resources·Resource allocation- Resources must be allocated to each user/job- Resource types - CPU cycles, main memory, file storage,I/O devices Special allocation code may be required, e.g., CPUscheduling routines depend on· Speed of the CPU, jobs, number of registers, etc.11
11 OS Services for Ensuring Efficiency • Systems with multiple users can gain efficiency by sharing the computer resources • Resource allocation – Resources must be allocated to each user/job – Resource types - CPU cycles, main memory, file storage, I/O devices – Special allocation code may be required, e.g., CPU scheduling routines depend on • Speed of the CPU, jobs, number of registers, etc
OsServicesforEnsuringEfficiency· Accounting - To keep track of-which users use how much and what kinds of resources: Usage- Accounting for billing users Accumulating usage statistics, can be used for·Reconfiguration of the system.Improvement of the efficiency12
12 OS Services for Ensuring Efficiency • Accounting - To keep track of – which users use how much and what kinds of resources • Usage – Accounting for billing users – Accumulating usage statistics, can be used for • Reconfiguration of the system • Improvement of the efficiency
OsServicesfor EnsuringEfficiency· Protection and security- Concurrent processes should not interfere w/ each other- Control the use of computerProtection- Ensure that all access to system resources is controlled? Security- User authentication by password to gain access Extends to defending external l/O devices from invalidaccess attempts13
13 OS Services for Ensuring Efficiency • Protection and security – Concurrent processes should not interfere w/ each other – Control the use of computer • Protection – Ensure that all access to system resources is controlled • Security – User authentication by password to gain access – Extends to defending external I/O devices from invalid access attempts
OsServicesforHelpingUsers User interface - Almost all operating systems have auserinterface (Ul)- Three formsCommand-Line(CLI)-Shell command·Batch- Shell script·GraphicsUserInterface(GUl- Windows system14
14 OS Services for Helping Users • User interface - Almost all operating systems have a user interface (UI). – Three forms • Command-Line (CLI) – Shell command • Batch – Shell script • Graphics User Interface (GUI) – Windows system
UserOperatingSystem Interface-CLI Command line interface or command interpreter-Allowsdirectcommand entry-Included in the kernel or treated as a special programSometimes multipleflavors implemented-shells- Linux: multiple shells (C shell, Korn Shell etc.- Third-party shell or free user-written shell- Most shells provide similar functionality (personalpreference)15
15 User Operating System Interface - CLI • Command line interface or command interpreter – Allows direct command entry – Included in the kernel or treated as a special program • Sometimes multiple flavors implemented – shells – Linux: multiple shells (C shell, Korn Shell etc.) – Third-party shell or free user-written shell – Most shells provide similar functionality (personal preference)