Chapter 2 Operating System Structures

Transcription

1 Chapter 2 Operating System Structures User Services User Interface Cmmand Line Interface cmmands entered via keybard Batch Interface cmmands are placed in text file which is executed Graphical User Interface icns, menus, pint, click, keybard Prgram Executin I/O Operatins File-System Manipulatin Cmmunicatins Shared Memry Message Passing Errr detectin Hardware Sftware Efficient Operatin Resurce Allcatin CPU Cycles Memry Access Files I/O Devices Accunting Prtectin Prcess Interference Effective User Identificatin (EUID) Security Authenticatin f Users Securing I/O Device Access Mnitring Invalid Access Attempts Virus Scanning

2 Cmmand Interpreter Sme perating systems prvide a kernel resident cmmand interpreter Windws XP Unix cmmand interpreters are special prgrams which are nt kernel resident The purpse f a cmmand interpreter is t get and execute the next user specified cmmand cmmand interpreter cntains the cde necessary t execute the cmmand uses the cmmand t identify a file t be laded int memry and executed cntains shell scripting languages fr easy manipulatin f cmmand line strings Shells cmmand interpreters prvided by vendrs, users r third parties Burne Shell C Shell Burne-Again Shell Krn Shell Bash Shell Graphical User Interfaces Desktp Metaphr (Xerx PARC Research Facility circa ) Icns Menus Files Flders (directries) Apple MacIntsh circa 1980 Unix Cmmn Desktp Envirnment (CDE) X-Windws Open-Surce GUI K Desktp Envirnment (KDE) GUI GNOME

3 System Calls Interface between user prgrams and O/S service rutines API Applicatin Prgramming Interface specifies a set f functins available t facilitate system calls prgram prtability Win 32 API -- Windws POSIX -- UNIX, Linux, Mac OS/X Java API -- JVM Run-Time Supprt System prvides a system-call interface intercepts functin calls frm the API & invkes the system call in the kernel Silberschatz page 57 Win32 API example Silberschatz page 58 figure 2.6 Passing Parameters pass parameters in registers stre parameters in a memry blck; pass the blck address Linux, Slaris Silberschatz page 59 figure 2.7 push parameters nt the stack Prcess Cntrl abrt( ) errr trap( ) memry dump debugger runtime errrs exit( ) wait( ) wait fr spawned prcess t cmplete executin and return result frk( ) spawn an prcess fr independent executin exec( ) lads new prcess int memry and initiates executin Actins fllwing Prcess Terminatin Cmmand Interpreter reads next cmmand GUI ppup windw asks fr guidance Batch terminates jb; cntinues with next jb reads cntrl card fr special errr cde instructins Errr Cdes 0 nrmal terminatin Larger numbers indicate mre serius situatins lck( ) reserve resurces, e.g., file1, fr exclusive use by prcess issuing the call release( ) releasing the lcked resurces printf( ) Standard C Library invkes write( ) system call in O/S O/S write( ) system call returns value t Standard C Library which returns it t printf( ) Silberschatz page 62 figure 2.9 FreeBSD memry map Silberschatz page 63 figure 2.11

4 File Management create( ) pen clse( ) delete( ) read( ) write( ) mkdir( ) rmdir( ) get_attribute( ) set_attribute( ) Unix File-Device Management Plicy -- devices are treated as if they were files Device Management acquire( ) release( ) Infrmatin Management date( ) returns date & time wh( ) versin( ) trace( ) prvides fr run-time trace requires hardware supprt t execute a trap after every instructin prfile( ) returns executin statistics Cmmunicatin message-passing Prcess Name A Hst Name IP Address Prcess Name B Hst Name IP Address OR Mailbx shared-memry Shared Memry Prcess Name A Hst Name IP Address Prcess Name B Hst Name IP Address Prtectin see Silberschatz Chapters 14 & 15

5 System Prgrams System Utilities File Management System Status Infrmatin perfrmance infrmatin cnfiguratin infrmatin, e.g., registry File Mdificatin text editrs grep, sed, awk tr, etc. Prgramming Language Supprt cmpilers assemblers surce cde debuggers interpreters Executin Utilities abslute laders relcatable laders link editrs verlay laders run-time debuggers Cmmunicatin O/S Design & Implementatin Design Gals Separatin between Plicy what will be dne Mechanism hw t d smething Slaris scheduler table driven time-share, batch prcessing, real-time, fair share Windws & Mac OS/X scheduler plicy & mechanism is built int the kernel Implementatin C Linux assembly language register management & device drivers C/C++ Windws assembly language register management & device drivers C r C/C++ Unix (all versins) assembly language register management & device drivers Areas f Critical Perfrmance memry manager CPU scheduler

6 O/S Structure IBM OS/ Mnlithic Structure Frederick Brks Mythical Man-Mnth MS DOS limited hardware supprt nt an O/S, i.e., NAOS page 71 figure 2.12 Original Unix limited hardware supprt mnlithic tendencies page 71 figure 2.13 Layered Structure Layer 0 Layer 1 Layer N Difficult t Specify the Levels fr Selected Cmpnents due t Cnflicting Requirements Windws NT (versin 1) Reduced Efficiency, Increased Size Windws XP Reduced Layering, Increased Functinality Hardware Layer Micrkernels Carnegie Melln University Mach O/S remve nnessential cmpnents frm the kernel implement them as system prgrams micrkernels prvide minimal prcess management minimal memry management full cmmunicatins between client prgrams and services running in user space uses message-passing new O/S services run in user space Digital Unix, i.e., Tru64 Unix Unix interface, Mach kernel Mac OS/X kernel Darwin QNX real-time system Mdules Object-Oriented Design & Develpment Dynamically Ladable Mdules Slaris, Linux, MacOS/X Slaris design Silberschatz page 75 figure 2.15 mre flexible than layered apprach Mac OS/X hybrid design Silberschatz page 75 figure 2.16 Mach + BSD cmprise kernel Mach prvides Memry Mngt (MM) Remte Prcedure Calls (RPC)Interprcess Cmmunicatins Facilities (IPC) Message-Passing Thread Scheduling BSD prvides Cmmand-Line Interface Netwrking Supprt File System Supprt POSIX API including Pthreads

7 Virtual Machines hst O/S prvides an interface that is identical t the underlying bare hardware guest O/S is prvided with a virtual set f hardware IBM VM370 created multiple virtual machines supprted IBM CMS single user O/S Benefits Sharing Hst Resurces with Strict Prtectin frm ther Virtual Installatins Sharing Resurces between Virtual Installatins, e.g., disk space Operating Systems Research & Develpment Installing prttype O/S fr testing Reinstalling Prductin O/S fr further develpment multiple O/S available n the develpers wrkstatin cncurrently prductin data center cnslidatin resurce ptimizatin Simulatin Emulatin Hst has a systems architecture different than that f the Guest Emulatin prgram translates each f the Guests instructins int the native instructin set f the Hsts system XP emulatr fr MS DOS Perfrmance Issues a prgram running n an emulatr will run an rder f magnitude slwer than the ld prgram Nt all features may be capture in the emulatin prgram Parallels Emulatr running n Mac OS/X supprting ther Operating Systems Para-Virtualizatin Slaris 10 znes (cntainers) Operating System & Devices are virtualized prvides each prcess with a zne; as if they were the nly prcess n the system virtual user mde virtual kernel mde must run in physical user mde system dwn (develpment) time thse actins that cause a transfer frm user mde t kernel mde n the physical machine must cause a transfer frm virtual user mde t virtual kernel mde n the virtual machine Implementatin virtual machine in virtual user mde issues a system call transfer f cntrl t the real machine virtual-machine mnitr virtual-machine mnitr can change register cntents & prgram cunter t reflect the virtual system call change the virtual mde frm user t kernel restart the virtual machine VMware Wrkstatin creates independent virtual Intel X86 machines runs n hst O/S, e.g., Linux, Windws Silberschatz page 81 figure 2.19

8 Java Virtual Machine (JVM) Sun Micrsystems 1995 Language Specificatin API Library JVM specificatin (abstract cmputer) architecture-neutral bytecde file, i.e., (.class file) JVM Cmpnents Class Lader lads Java prgram.class files + Java API.class files Java Interpreter f bytecdes Verifier checks that.class files are valid bytecde, i.e., will nt underflw nr verflw the stack des nt perfrm pinter arithmetic Garbage Cllectr reclaims unused memry as sn as pssible JVM Implementatin Sftware interprets bytecde instructins each time they are executed JIT (just-in-time) cmpiler the first time the bytecde is executed, it is cnverted t native machine cde the native cde is cached fr repeat usage Hardware special java chip that executes bytecde as native machine cde.net Framewrk Cmmn Language Runtime (CLR) implementatin f the.net Virtual Machine C# VB.NET CLR cmpiles the surce cde int an intermediate architecture-independent language called Micrsft Intermediate Language (MS-IL); these files, i.e., assemblies, als include metadata and have file extensins f either.dll r.exe CLR lads the assemblies int the Applicatin Dmain as the executing prgram requests instructins, the CLR cnverts he MS-IL instructins int native cde fr executin and where they are stred fr repeat usage as demanded Silberschatz page 83 figure 2.21 Debugging Failure Analysis -- Lcating Bugs, i.e., Errrs Lg Files errr infrmatin Cre Dump image f memry at a particular pint in time Debugger explre the prcess, i.e., cde, registers, memry and ther run-time infrmatin Kernel Failure crash OS detects a kernel failure, it writes the cntents f memry t a sectin f disk w/ a file-system When system rebts, a system prcess cpies the crash dump data t the crash dump file in the file-system

9 Perfrmance Tuning, i.e., Lcating Bttlenecks Hardware implementatin trace listings prduced by the hardware Interactive investigative tls query state f the system Prfiling peridically samples the IP t determine what cde is being executed yields statistical trends Slaris DTrace Dynamic Tracing Facility Cmpnents Cmpiler generates a byte cde (ECB) that is run in the kernel t enable prbes cnsumers in user mde cmmunicatins between users and kernel prbes Framewrk Prvider supplies prbes written w/in the Framewrk Cnsumer requests prvider create ne r mre prbes Actins prbe created kernel prvides a HashTable Data Structure t keep track f the prbes prbe enabled a bit f cde in the area t be prbed is rewritten t call the prbe cde cntinues its riginal peratin kernel executes the ECB upn demand prbe cnsumer terminates ECB are remved if there are n ECB s cnsuming a prbe, the prbe is remved rewriting the cde t remve the prbe call Infrmatin Generated kernel system state prcesses System Generatin Hardware Infrmatin Internal Sensing Operatr Query SYSGEN Surce Cde Mdificatin + Cmpilatin Table Creatin Mdules are selected frm a precmpiled Library unselected mdules are remved frm the system selected Mdules are linked t create the peratinal system Table Driven entire Library is always part f the system selectin f mdules ccurs at run-time Enabling Cntrl Blcks (ECB) cntain a list f actins t be perfrmed when a prbe fires cntains a predicates, i.e., an if statement, t filter perfrmance (whether r nt the prbe applies t the ECB)

10 System Bt btstrap (lader) prgram firmware ROM, EPROM, etc events reset event PC laded with address f btstrap lader btstrap lader fragment -- firmware resident lcates bt blck -- disk resident bt blck cntains remainder f the btstrap lader lads btstrap prgram run diagnstics initialize system lcates kernel lads kernel starts kernel executing