Mac OS X uses a Mach scheduling system with different process priorities like normal, high, and real-time. It also uses pThreads API to adjust thread priorities within tasks. Kernel threads are created through I/O Kit functions and deleted using thread_terminate after locking and disabling timers. The renice command can alter the priority of running processes by ID, group, or user.

1. Mac OS X
Process Management Saksham
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3.  Mach Scheduling is based on a system of run queues based on process
priorities.
o Normal Priority
o System High Priority
o Kernel Mode Only
o Real Time

4. CPU Bound
Threads
Low Priority
I/O Threads High Priority
More CPU Need
Less CPU Need

5. pThreads API
» pthreads API adjusts the priority of threads within a given task .
pthread_setschedparam(pthread_t , int , struct ) ;
ID Parameters
Influence Scheduling

6.  Used to create, destroy, and alter kernel threads .
 Kernel threads would be of limited utility without certain services .

7. Creating Kernel Threads
Created through I/O Kit
• IOCreateThread
• IOThreadSelf
• IOExitThread

8. Deleting Kernel Threads
Thread_terminate is used to destroy threads.
Before tearing down a thread with thread_terminate :
» Lock the thread .
» Disable any outstanding timers .

10. Alters priority of running processes.
It takes ID of
• A Process
• A Process Group
• A User

11. renice priority [[-p]] pid …][[-g] pgrp …] [[-u] user …]
renice –n increment [[-p] pid …] [[-g] pgrp …] [[-u] user …]
-p interpreted to be process ID
-g interpreted to be group ID
-n changing to a particular priority
-u interpreted to be user ID

12. http://www.apple.com/developer/
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Sakshi Mantri
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