What does an Operating System do?Jonathan GeislerFebruary 5, 2007Jonathan Geisler What does an Operating System do?Perspectives on an OSThere are three perspe ctive s on an OS:1The user is concerned with the services it provides.2The programmer is concerned with the interfaces it provides.3The designer is concerned with the internal components andtheir interconnections.Jonathan Geisler What does an Operating System do?Perspectives on an OSThere are three perspe ctive s on an OS:1The user is concerned with the services it provides.2The programmer is concerned with the interfaces it provides.3The designer is concerned with the internal components andtheir interconnections.Jonathan Geisler What does an Operating System do?Perspectives on an OSThere are three perspe ctive s on an OS:1The user is concerned with the services it provides.2The programmer is concerned with the interfaces it provides.3The designer is concerned with the internal components andtheir interconnections.Jonathan Geisler What does an Operating System do?Services ProvidedUser interface (CLI vs. GUI)Run programsI/OAccess to filesNetworkingError handlingProtection & SecurityAccountingManaging resourcesJonathan Geisler What does an Operating System do?Interfaces Provided (i.e., system calls)This is how a program asks the OS to perform a specific service.Think back to chapter one, how do they work? Notice how manycalls were in the simple example from the book. This requiresthem to be done very efficiently.Jonathan Geisler What does an Operating System do?Typical system callsThis is a list of the type of system calls you would expect to find inmost OSes:endabortcreate processget/set process attributeswaitsignaldate/timeopenreadwriteget/set file attributescloseacquire resourcecreate connectionJonathan Geisler What does an Operating System do?Interesting system callsEvery operating system has its share of common system calls. Hereare a couple unique ones that you may not have thought aboutbefore:Trace can allow profiling programs to run or strace on LinuxStep allows debugging programs to workTerminate and Stay Resident allows MS-DOS to fakemultitaskingJonathan Geisler What does an Operating System do?Interesting system callsEvery operating system has its share of common system calls. Hereare a couple unique ones that you may not have thought aboutbefore:Trace can allow profiling programs to run or strace on LinuxStep allows debugging programs to workTerminate and Stay Resident allows MS-DOS to fakemultitaskingJonathan Geisler What does an Operating System do?Interesting system callsEvery operating system has its share of common system calls. Hereare a couple unique ones that you may not have thought aboutbefore:Trace can allow profiling programs to run or strace on LinuxStep allows debugging programs to workTerminate and Stay Resident allows MS-DOS to fakemultitaskingJonathan Geisler What does an Operating System do?Components and InterconnectionsComponentsManagementProcessMemoryFileI/OStorageNetworkingProtection &SecurityCommandInterpreterInterconnection typesLayered (OS/2)Pro: modularityCons: dependencies & efficiencyMicrokernel (Mach, WinNT, Mac OS X,etc.)Pros: extendibility, portability, &securityCons: efficiencyWhatever works (Linux, WinXP, etc.)Pro: run-time efficiencyCons: modularity & extendibilityJonathan Geisler What does an Operating System do?Components and InterconnectionsComponentsManagementProcessMemoryFileI/OStorageNetworkingProtection &SecurityCommandInterpreterInterconnection typesLayered (OS/2)Pro: modularityCons: dependencies & efficiencyMicrokernel (Mach, WinNT, Mac OS X,etc.)Pros: extendibility, portability, &securityCons: efficiencyWhatever works (Linux, WinXP, etc.)Pro: run-time efficiencyCons: modularity & extendibilityJonathan Geisler What does an Operating System do?Components and InterconnectionsComponentsManagementProcessMemoryFileI/OStorageNetworkingProtection &SecurityCommandInterpreterInterconnection typesLayered (OS/2)Pro: modularityCons: dependencies & efficiencyMicrokernel (Mach, WinNT, Mac OS X,etc.)Pros: extendibility, portability, &securityCons: efficiencyWhatever works (Linux, WinXP, etc.)Pro: run-time efficiencyCons: modularity & extendibilityJonathan Geisler What does an Operating System do?Components and InterconnectionsComponentsManagementProcessMemoryFileI/OStorageNetworkingProtection &SecurityCommandInterpreterInterconnection typesLayered (OS/2)Pro: modularityCons: dependencies & efficiencyMicrokernel (Mach, WinNT, Mac OS X,etc.)Pros: extendibility, portability, &securityCons: efficiencyWhatever works (Linux, WinXP, etc.)Pro: run-time efficiencyCons: modularity & extendibilityJonathan Geisler What does an Operating System do?Components and InterconnectionsComponentsManagementProcessMemoryFileI/OStorageNetworkingProtection &SecurityCommandInterpreterInterconnection typesLayered (OS/2)Pro: modularityCons: dependencies & efficiencyMicrokernel (Mach, WinNT, Mac OS X,etc.)Pros: extendibility, portability, &securityCons: efficiencyWhatever works (Linux, WinXP, etc.)Pro: run-time efficiencyCons: modularity & extendibilityJonathan Geisler What does an Operating System do?Components and InterconnectionsComponentsManagementProcessMemoryFileI/OStorageNetworkingProtection &SecurityCommandInterpreterInterconnection typesLayered (OS/2)Pro: modularityCons: dependencies & efficiencyMicrokernel (Mach, WinNT, Mac OS X,etc.)Pros: extendibility, portability, &securityCons: efficiencyWhatever works (Linux, WinXP, etc.)Pro: run-time efficiencyCons: modularity & extendibilityJonathan Geisler What does an Operating System do?Components and InterconnectionsComponentsManagementProcessMemoryFileI/OStorageNetworkingProtection &SecurityCommandInterpreterInterconnection typesLayered (OS/2)Pro: modularityCons: dependencies & efficiencyMicrokernel (Mach, WinNT, Mac OS X,etc.)Pros: extendibility, portability, &securityCons: efficiencyWhatever works (Linux, WinXP, etc.)Pro: run-time efficiencyCons: modularity & extendibilityJonathan Geisler What does an Operating System do?Components and InterconnectionsComponentsManagementProcessMemoryFileI/OStorageNetworkingProtection &SecurityCommandInterpreterInterconnection typesLayered (OS/2)Pro: modularityCons: dependencies & efficiencyMicrokernel (Mach, WinNT, Mac OS X,etc.)Pros: extendibility, portability, &securityCons: efficiencyWhatever works (Linux, WinXP, etc.)Pro: run-time efficiencyCons: modularity & extendibilityJonathan Geisler What does an Operating System
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