Mac OS X

1. Mac OS X CS-351 (Operating Systems), Spring 2001) Section 1 Term Project by Jonathan Chapin - chapinjs@jmu.edu - x7785 Brian Jones - jonesba@jmu.edu 442-9251 Frank Machnick - machnife@jmu.edu 435-7922 Paul Veraa - veraapr@jmu.edu - 438-4064

2. Mac OS X: Overview & System Fundamentals • Integrated desktop and server OS • Full replacement of OS 9 • Combines reliability and performance with simple and refined user interface expected of Mac • New, so not commercially successful

3. Mac OS X: Overview & System Fundamentals (cont.) • A few problems - speed of GUI rendering sluggish • Mac 9 applications are emulated slowly

4. Rebuilt from the ground up • Mach micro-kernel architecture • manages cpu usage and memory • handles scheduling • provides memory protection • provides a messaging infrastructure

5. To provide more efficiency • FreeBSD • file system management, • networking, • security policies, • the standard BSD process model with process IDs and signals. • It also provides the standard POSIX threads implementation which many applications (such as MySQL) find very useful.

6. Improvements • Enhancements have been added to the file system buffer cache and file I/O clustering. • adaptive and speculative read ahead, • user process controlled read ahead, • and time aging of the file system buffer cache • Additions to file system: • HFS, HFS+, and Apple extensions to the ISO9660 CD file system standard.

7. Enhanced state of the Art? • Quartz graphics subsystem • PDF for all graphics • dynamic resizing • vectors instead of bitmap • Reliability and functionality are a reality • Supports symmetric multiprocessing

8. Allowable process states

9. Process Management • Getting Process Information • GetCurrentProcess: Gets information about the current process, if any. • GetFrontProcess: Gets the process serial number of the front process. • GetNextProcess: Gets information about the next process, if any, in the Process Manager's internal list of open processes. • GetProcessInformation: Get information about a specific process. • SameProcess: Determines whether two process serial numbers specify the same process. • SetFrontProcess: Sets the front process. • WakeUpProcess: Makes a process suspended by WaitNextEvent eligible to receive CPU time.

10. Process Management • Launching Applications and Desk Accessories • LaunchApplication: Launches an application. • LaunchDeskAccessory: Launches desk accessories. Use this function only when your application needs to launch a desk accessory for some reason other than the user's choosing one from the Apple menu.

11. Process Management • Terminating Processes • ExitToShell: Terminates your application directly.

12. Memory Management • Accessing Heap Zones • ApplicationZone: Returns a pointer to the original application heap zone. • GetZone: Returns a pointer to the current heap zone. • HandleZone: Returns a pointer to the heap zone containing a specified handle. • PtrZone: Returns a pointer to the heap zone containing a specified pointer. • SetZone: Changes the current heap zone. • SystemZone: Returns a pointer to the system heap zone.

13. Memory Management • Allocating Temporary Memory • TempFreeMem: Returns the total amount of memory available for temporary allocation. • TempMaxMem: Compacts the current heap zone and returns the size of the largest contiguous block available for temporary allocation. • TempNewHandle: Allocates a new relocatable block of temporary memory.

14. Memory Management • Allocating and Releasing Nonrelocatable Blocks of Memory • DisposePtr: Releases memory occupied by a nonrelocatable block. • NewPtr: Allocates a nonrelocatable block of memory of a specified size. • NewPtrClear: Allocates a nonrelocatable block of memory of a specified size with all its bytes set to 0. • NewPtrSys: Allocates a nonrelocatable block of memory of a specified size in the system heap. • NewPtrSysClear: Allocates a nonrelocatable block of a specified size in the system heap with all its bytes set to 0.

15. File Management • Accessing Information About Files and Directories on HFS Volumes • FSGetCatalogInfo: Returns catalog information about a file or directory. You can use this function to map an FSRef to an FSSpec. • FSSetCatalogInfo: Sets catalog information about a file or directory. • FSpGetFInfo: Obtains the Finder information for a file. • FSpSetFInfo: Sets the Finder information about a file. • HGetFInfo: Obtains the Finder information for a file. • HSetFInfo: Sets the Finder information for a file.

16. File Management • Allocating Storage for Forks on HFS Plus Volumes • FSAllocateFork: Allocates space on a volume to an open fork. • PBAllocateForkAsync: Allocates space on a volume to an open fork. • PBAllocateForkSync : Allocates space on a volume to an open fork.

17. File Management • Comparing File System References • FSCompareFSRefs: Determines whether two FSRef structures refer to the same file or directory. • PBCompareFSRefsAsync: Determines whether two FSRef structures refer to the same file or directory. • PBCompareFSRefsSync: Determines whether two FSRef structures refer to the same file or directory.

18. File Management • Controlling Directory Access • PBHGetDirAccessAsync: Returns the access control information for a directory. • PBHGetDirAccessSync: Returns the access control information for a directory. • PBHSetDirAccessAsync: Changes the access control information for a directory. • PBHSetDirAccessSync: Changes the access control information for a directory.

19. Threads • Multiple threads per process • Processes are called “tasks” • tasks are a collection of resource and contain threads • Threads are point of control inside of tasks • potentially execute in parallel (SMP) • minimal state and low overhead

20. Types of threads • High priority real time - fixed priority • execute for certain quantum • Timesharing threads • piority is raised and lowered to balance its resource consumption against other threads

21. Tasks • Expensive entities • cannot share resources with another task • All threads share task’s resources • Traps are requests for services to the Kernel on behalf of the thread • create, delete and state change

22. Mutual Exclusion and Synchronization • Use of ports for unidirectional communication • Resources are referred to in object oriented fashion • Objects can have multiple ports • name and control ports

23. Mutual Exclusion and Synchronization • Message queues - A message may consist of pure data, copies of memory ranges, port rights, kernel and implicit attributes, such as the sender s security token. • Semaphores - Counting semaphores supporting wait, post, and post all operations, but contain no data. • Notifications - support the post and wait methods, but with the addition of a state field. Each post overwrites the previous state. \ • Locksets - During the transaction, the thread holds the lock. When it returns from the transaction, the lock is released. • Remote procedure calls (RPC) - RPCs are designed to facilitate and optimize remote procedure calls.

24. Scheduling • Mac OS 9 was Cooperative Multitasking • Depends on honest processe • Max OS X - preemptive multitasking with dynamic priority adjustment • Darwin assigns priorities • Mach swapps processes • Preemption: time-sharing, round robin, and through first in first out (FIFO) fixed priority.

25. File Management • Supports several systems • Mac OS Extended Format, BSD standard file system format, the industry standard for networking file systems (NFS), and ISO 9660 • Third party file systems mounted through virtual file system