1. Processes, Threads and Scheduling OS Lecture #4

2. Processes Unit of resource allocation in the OS Allocation of space Clock time The abstraction of a process provides fault isolation between different “programs” (read: processes) Each process lives in its own world OS gives each process the illusion that it is the king of all resources, including processor time

3. Threads Unit of execution Assign a thread to a process to make it “runnable” Can have multiple threads in a process Threads “share” state -- no “fault isolation” Typically, threads also share the time- quantum allocated to their process Creating more threads typically does not mean your process will get more time on the processor

4. So why use threads? Operating System file.read Concurrency * to mask blocking I/O Zzzzzz …