SOLARIS

1. SOLARIS Andrew Trice Jon Rossman Alex Kozel Gary Greene Jake Cyrus

2. What is Solaris? • UNIX based operating system made by Sun: • SPARC and Intel Architecture systems • SunOS • Designed for the network • Designed for efficiency

3. Basic Requirements • SPARC (32- and 64-bit) or Intel Architecture (32-bit) platforms • Disk space: 600 Mbytes for desktops; one Gbyte for servers • Memory: 64 Mbytes minimum

4. Solaris 8 • Efficiently manage resources and provide a higher level of service • Minimization of planned and unplanned downtime • Reduction of administration errors • Simplification of troubleshooting • High-speed, reliable access to the data

5. An Important Note About Directories • Similar to DOS • “Home" directory • current working directory when they login • Case sensitive

6. Who Uses Solaris? • AOL (America On Line), • Apple Computers (in addition to Mac OS X Server), • AT&T, • BillGates.com, • BMGMusicService.com, • CNN (Cable News Network) • CNNSI.com • Discovery.com • Disney.com • E-Trade.com • General Electric • MTV

7. Solaris Security • Solaris incorporates four levels of security: • Level 1 - consists of features and tools that help administrators tightly control who can log onto the system. • Level 2 - describes tools that enable administrators to set the overall security state of the system. • Level 3 - covers Secure Distributed services and Developers Platforms, describing how Solaris supports different authentication and encryption mechanisms. • Level 4 - describes the tools to control access to the physical network.

8. Process Management • Process creation and termination • Process scheduling and dispatching • Process switching • Process synchronization and support for interprocess communication • Management of process control blocks

9. Process Creation • A slot in the process table is allocated for the new process • A unique process ID is assigned to the child process • A copy of the process image of the parent is made • Counters for any files owned by the parents are incremented to show that an additional process now owns those files • The child process is set to the ready state • The ID number of the child is returned to the parent process and a value of 0 is returned to the child process.

10. Process Scheduling • Two different types of processes • Real-time processes • Time-sharing processes • All the real-time processes are given higher priority than any time-sharing processes. • Whenever a real-time process is ready to run, it is picked up for execution by the scheduler. • the frequency of priority update is once every 100ms.

11. Process Switching • Running process is interrupted and the OS assigns another process to the running state. • Interrupt or Trap • If an interrupt occurs, the interrupt goes to the interrupt handler and the goes to an OS routine that is concerned with it. • If a trap occurs, if it is fatal, the process is switched, if not, it depends on the error. • Mode switching in Solaris • Saves the context of the current program being executed • Sets the program counter to the starting address of an interrupt-handler • Switches from user mode to kernel mode to have higher privilege

12. Process Synchronization • To enforce mutual exclusion and event ordering • Solaris implements thread synchronization using: • MUTEX Lock • mutex_enter(), mutex_exit(), mutex_tryenter() • Reader/Writer Lock • rw_enter(), rw_exit(), rw_tryenter(), rw_downgrade(), rw_tryupgrade() • Semaphores • sema_p(), sema_v(), sema_tryp() • Condition Variables • cv_wait(), cv_signal(), vc_broadcast()

13. Management of Process Control Blocks • The data needed by the operating system to control the process • This includes • Process state • e.g. Running, ready waiting • Priority • Scheduling priority of process • Scheduling-related information • e.g. Amount of time process has been waiting • Event • Identity of event the process is awaiting before it can be resumed

14. Threads in Solaris • Threads can be implemented using Solaris’ own API, Solaris threads, or with POSIX’s API, pthreads. • Both APIs behave similarly in action and syntax. • They are not 100% compatible, however, as each API has functions that are not present in the other.

15. Threads in Solaris • Solaris allows the safe use of both APIs in the same program. • This gives a programmer the flexibility of exploiting the exclusive functions found in Solaris threads and pthreads.

16. Unique Solaris thread features: Reader/Writer Locks Ability to create “daemon” threads Suspending and continuing a thread Setting concurrency; determining concurrency level Unique pthread features: Attribute objects (these replace many Solaris arguments or flags with pointers to pthreads attribute objects) Cancellation semantics Scheduling policies Threads in Solaris

17. Deadlock Avoidance • Solaris utilizes several synchronization objects in order to prevent deadlock. • These objects are: • Mutual Exclusion Locks • Condition Variables • Semaphores

18. Mutual Exclusion Locks • Solaris uses mutual exclusion locks (mutexes) to serialize thread execution. • Mutual exclusion locks synchronize threads, usually by ensuring that only one thread at a time executes a critical section of code. • Mutex locks can also preserve single-threaded code.

19. Condition Variables • Condition variables atomically block threads until a particular condition is true. • The condition is tested under the protection of a mutual exclusion lock. • When the condition is false, a thread usually blocks on a condition variable and atomically releases the mutex waiting for the condition to change. • When another thread changes the condition, it can signal the associated condition variable to cause one or more waiting threads to wake up, acquire the mutex again, and reevaluate the condition.

20. Semaphores • Semaphores are integers. • A thread waits for permission to proceed and then signals that it has proceeded by performing a P operation on the semaphore. • the thread must wait until the semaphore's value is positive, then change the semaphore's value by subtracting one from it. • When it is finished, the thread performs a V operation, which changes the semaphore's value by adding one to it.

21. Solaris Memory Management Two kinds: Virtual Memory Paging System Kernel Memory Allocator

22. Kernel Memory Allocator • Kernel Processes: • Many buffers and small tables • Lazy buddy system

23. Virtual Memory Paging System • User Processes • Data Structures: • Page table • Disk block descriptor • Page frame data table • Swap use table

24. End of page list Front of page list Backhand Handspread Fronthand Global Clock-hand LRU

25. Solaris File Systems • Uses UFS (UNIX File System) • Directories organize files • Files hold information • Directories are files. • Only hold information about other files. • Do not contain other files.

26. Solaris File Systems • File System has 3 components. • Superblock • Inodes • Blocks

27. Solaris File Systems • Filenames can be up to 255 characters • Almost any charcters are allowed. • Even ! $ * _ ( )

28. Solaris File Systems • Organized like a typical UNIX environment • Root directory is base of organization. • Every other file & directory extends from root.