1. What important part of the process switch operation is not shown in Figure 3.4? 2. What is the operational difference between single-threaded and multi-threaded processes? i.e., how does it change the usage of each? 3. What kinds of operations take advantage of threads? Think of depth and breadth. 1).consider task parallelism 2).consider data parallelism 4.What is the difference between Many to One, One to One, and Many to Many models? 1).What are the benefits and constraints of each of these? 2).Provide examples of each of these 3).How does the two-level model help thread operations? process Po operating system process P interrupt or system call executing save state into PCBo idle reload state from PCB1 dle interrupt or system call executing save state into PCB1 idle reload state from PCB0 executing Figure 3.4 Diagram showing CPU switch from process to process. Solution PCB daigaram. 1.The Program control Block diagram is important ,we have PCB in the diagram,but in detail. For each process there is a Process Control Block, PCB, which stores the following ( types of ) process-specific information, as illustrated in Figure 3.1. ( Specific details may vary from system to system. ) •Process State - Running, waiting, etc., as discussed above. •Process ID, and parent process ID. •CPU registers and Program Counter - These need to be saved and restored when swapping processes in and out of the CPU. •CPU-Scheduling information - Such as priority information and pointers to scheduling queues. •Memory-Management information - E.g. page tables or segment tables. •Accounting information - user and kernel CPU time consumed, account numbers, limits, etc. •I/O Status information - Devices allocated, open file tables, etc. 2.With a single thread process, the process runs/executes on single path.With multiple thread process is where a process runs/executes on two or more paths. Applications with multithreading implementation increases its responsiveness to the application’s users, for instance; with traditional single-threaded process implementation within a web server can serve only one client request at a time and can make the waiting period for other users requesting services a very long time. With more efficient multithreaded server implementation; separate threads can be created to respond to different users’ requests. Multithreading technique in the above example increased the application responsiveness to the users’ requests. 3. Multiple Processes ,example proxy server satisfying the requests for a number of computers on a LAN would be benefited by a multi-threaded process. Task parallelism is the simultaneous execution on multiple cores of many different functions across the same or different datasets. This form of parallelism covers the execution of computer programs across multiple processors on same or multiple machines. It focuses on executing different operations in parallel to fully utilize the available computing resources in form of proces.

1. 1. What important part of the process switch operation is not shown in Figure 3.4?
2. What is the operational difference between single-threaded and multi-threaded processes? i.e.,
how does it change the usage of each?
3. What kinds of operations take advantage of threads? Think of depth and breadth.
1).consider task parallelism
2).consider data parallelism
4.What is the difference between Many to One, One to One, and Many to Many models?
1).What are the benefits and constraints of each of these?
2).Provide examples of each of these
3).How does the two-level model help thread operations? process Po operating system process P
interrupt or system call executing save state into PCBo idle reload state from PCB1 dle interrupt
or system call executing save state into PCB1 idle reload state from PCB0 executing Figure 3.4
Diagram showing CPU switch from process to process.
Solution
PCB daigaram.
1.The Program control Block diagram is important ,we have PCB in the diagram,but in detail.
For each process there is a Process Control Block, PCB,
which stores the following ( types of ) process-specific information, as illustrated in Figure 3.1. (
Specific details may vary from system to system. )
•Process State - Running, waiting, etc., as discussed above.
•Process ID, and parent process ID.
•CPU registers and Program Counter - These need to be saved and restored when swapping
processes in and out of the CPU.
•CPU-Scheduling information - Such as priority information and pointers to scheduling queues.
•Memory-Management information - E.g. page tables or segment tables.
•Accounting information - user and kernel CPU time consumed, account numbers, limits, etc.
•I/O Status information - Devices allocated, open file tables, etc.
2.With a single thread process, the process runs/executes on single path.With multiple thread
process is where a process runs/executes on two or more paths.
Applications with multithreading implementation increases its responsiveness to the
application’s users, for instance;
with traditional single-threaded process implementation within a web server can serve only one
client request at a time and can make the waiting period for other users requesting services a very

2. long time.
With more efficient multithreaded server implementation; separate threads can be created to
respond to different users’ requests.
Multithreading technique in the above example increased the application responsiveness to the
users’ requests.
3.
Multiple Processes ,example proxy server satisfying the requests for a number of computers on a
LAN would be benefited by a multi-threaded process.
Task parallelism is the simultaneous execution on multiple cores of many different functions
across the same or different datasets.
This form of parallelism covers the execution of computer programs across multiple processors
on same or multiple machines. It focuses on executing different operations in parallel to fully
utilize the available computing resources in form of processors and memory.
example of task parallelism would be an application creating threads for doing parallel
processing where each thread is responsible for performing a different operation
This form of parallelism focuses on distribution of data sets across the multiple computation
programs. In this form, same operations are performed on different parallel computing
processors on the distributed data sub set.
One example of data parallelism would be to divide the input data into sub sets and pass it to the
threads performing same task on different CPUs
Data parallelism (aka SIMD) is the simultaneous execution on multiple cores of the same
function across the elements of a dataset.
4.
•One popular variation of the many-to-many model is the two-tier model, which allows either
many-to-many or one-to-one operation.
Example:
•IRIX, HP-UX, and Tru64 UNIX use the two-tier model, as did Solaris prior to Solaris 9.
a. Many to one Model
•In the many-to-one model, many user-level threads are all mapped onto a single kernel
thread.Thread management is handled by the thread library in user space, which is very efficient.
Example
•Green threads for Solaris and GNU Portable Threads implement the many-to-one model in the
past, but few systems continue to do so today.
b. One-To-One Model
•The one-to-one model creates a separate kernel thread to handle each user thread.One-to-one
model overcomes the problems listed above involving blocking system calls and the splitting of

3. processes across multiple CPUs.
Example:
•Linux and Windows from 95 to XP implement the one-to-one model for threads.
c.Many-To-Many Model
•The many-to-many model multiplexes any number of user threads onto an equal or smaller
number of kernel threads, combining the best features of the one-to-one and many-to-one
models.
Users have no restrictions on the number of threads created.
Example:
•Individual processes may be allocated variable numbers of kernel threads, depending on the
number of CPUs present and other factors.