![Bounded-Buffer – Shared-
Memory Solution
Shared data
#define BUFFER_SIZE 10
typedef struct {
. . .
} item;
item buffer[BUFFER_SIZE];
int in = 0;#if free one process enter in
int out = 0;# one process comes out and
becomes NULL
Solution is correct, but can only use BUFFER_SIZE-1 elements](https://image.slidesharecdn.com/inter-processcommunicationinoperatingsystem-231102073525-0d5bcfb4/85/Inter-Process-communication-in-Operating-System-ppt-10-320.jpg)
![Bounded-Buffer – Producer
item next_produced;
while (true) {
/* produce an item in next produced */
while (((in + 1) % BUFFER_SIZE) == out)
; /* do nothing */
buffer[in] = next_produced; #next new item
is stored
in = (in + 1) % BUFFER_SIZE;
}](https://image.slidesharecdn.com/inter-processcommunicationinoperatingsystem-231102073525-0d5bcfb4/85/Inter-Process-communication-in-Operating-System-ppt-11-320.jpg)
![Bounded Buffer – Consumer
item next_consumed;
while (true) {
while (in == out)
; /* do nothing */
next_consumed = buffer[out];
out = (out + 1) % BUFFER_SIZE;
/* consume the item in next
consumed */
}](https://image.slidesharecdn.com/inter-processcommunicationinoperatingsystem-231102073525-0d5bcfb4/85/Inter-Process-communication-in-Operating-System-ppt-12-320.jpg)
More Related Content
Similar to Inter-Process communication in Operating System.ppt (20)
![BBC NW_Tech Facilities_30 Odd Yrs Ago [J].pdf](https://cdn.slidesharecdn.com/ss_thumbnails/bbcnwtechfacilities30oddyrsagoj-250830230619-0d747bd6-thumbnail.jpg?width=560&fit=bounds)
Inter-Process communication in Operating System.ppt
- 1. Inter-process Communication in Operating System 1. Inter-process Communication 2. Communication Model 3. Communication Process 4. Shared Memory 5. Producer-Consumer Problem 6. Direct Communication 7. Indirect Communication Ms.C.Nithiya Computer Science and Engineering KIT-Kalaignarkarunanidhi Institute Of Technology
- 2. Processes within a system may be independent or cooperating Cooperating process can affect or be affected by other processes, including sharing data Reasons for cooperating processes: Information sharing Computation speedup Modularity Convenience Cooperating processes need interprocess communication (IPC) Two models of IPC Shared memory Message passing Interprocess Communication
- 3. Communications Models (a) Message passing. (b) shared memory.
- 4. Cooperating Processes Independent process cannot affect or be affected by the execution of another process Cooperating process can affect or be affected by the execution of another process Advantages of process cooperation Information sharing Computation speed-up Modularity Convenience
- 5. Interprocess Communication – Shared Memory An area of memory shared among the processes that wish to communicate The communication is under the control of the users processes not the operating system. Major issues is to provide mechanism that will allow the user processes to synchronize their actions when they access shared memory.
- 6. Producer-Consumer Problem Under cooperating processes, producer process produces information that is consumed by a consumer process unbounded-buffer places no practical limit on the size of the buffer bounded-buffer assumes that there is a fixed buffer size
- 7. Examples of IPC Systems - POSIX n POSIX Shared Memory include shared memory and message passing. l Process first creates shared memory segment shm_fd = shm_open(name, O_CREAT | O_RDWR, 0666); l Also used to open an existing segment to share it. It returns a integer value. l Set the size of the object ftruncate(shm fd, 4096); l Now the process could write to the shared memory sprintf(shared memory, "Writing to shared memory"); Mmap()memory mapping func creates a pointer to shared memory object.
- 10. Bounded-Buffer – Shared- Memory Solution Shared data #define BUFFER_SIZE 10 typedef struct { . . . } item; item buffer[BUFFER_SIZE]; int in = 0;#if free one process enter in int out = 0;# one process comes out and becomes NULL Solution is correct, but can only use BUFFER_SIZE-1 elements
- 11. Bounded-Buffer – Producer item next_produced; while (true) { /* produce an item in next produced */ while (((in + 1) % BUFFER_SIZE) == out) ; /* do nothing */ buffer[in] = next_produced; #next new item is stored in = (in + 1) % BUFFER_SIZE; }
- 12. Bounded Buffer – Consumer item next_consumed; while (true) { while (in == out) ; /* do nothing */ next_consumed = buffer[out]; out = (out + 1) % BUFFER_SIZE; /* consume the item in next consumed */ }
- 13. Interprocess Communication – Message Passing Mechanism for processes to communicate and to synchronize their actions without sharing address space. Message system – process communication takes place between different computer systems through network. IPC facility provides two operations: send(message) receive(message) The message size is either fixed or variable
- 14. Message Passing (Cont.) If processes P and Q wish to communicate, they need to: Establish a communication link between them Exchange messages via send/receive Implementation issues: How are links established? Can a link be associated with more than two processes? How many links can there be between every pair of communicating processes? What is the capacity of a link? Is the size of a message that the link can accommodate fixed or variable? Is a link unidirectional or bi-directional?
- 15. Message Passing (Cont.) Implementation of communication link Issues faced : Naming Synchronization Buffering Logical: Direct or indirect Synchronous or asynchronous Automatic or explicit buffering
- 16. Direct Communication Processes must name each other explicitly: send (P, message) – send a message to process P receive(Q, message) – receive a message from process Q Properties of communication link Links are established automatically A link is associated with exactly one pair of communicating processes Between each pair there exists exactly one link The link may be unidirectional, but is usually bi- directional
- 17. Indirect Communication Messages are directed and received from mailboxes (also referred to as ports) Each mailbox has a unique id Processes can communicate only if they share a mailbox Properties of communication link Link established only if processes share a common mailbox A link may be associated with many processes Each pair of processes may share several communication links Link may be unidirectional or bi-directional
- 18. Indirect Communication Operations create a new mailbox (port) send and receive messages through mailbox destroy a mailbox Primitives are defined as: send(A, message) – send a message to mailbox A receive(A, message) – receive a message from mailbox A
- 19. Indirect Communication Mailbox sharing P1, P2, and P3 share mailbox A P1, sends; P2 and P3 receive Who gets the message? Solutions Allow a link to be associated with at most two processes Allow only one process at a time to execute a receive operation Allow the system to select arbitrarily the receiver. Sender is notified who the receiver was.
- 20. Synchronization Implement : Message passing may be either blocking or non- blocking Blocking is considered synchronous Blocking send -- the sender is blocked until the message is received Blocking receive -- the receiver is blocked until a message is available Non-blocking is considered asynchronous Non-blocking send -- the sender sends the message and continue Non-blocking receive -- the receiver receives: A valid message, or Null message Different combinations possible
- 21. Synchronization (Cont.) Producer-consumer becomes little important. message next_produced; while (true) { /* produce an item in next produced */ send(next_produced); } message next_consumed; while (true) { receive(next_consumed); /* consume the item in next consumed */ }
- 22. Buffering Send and receive will reside in temp queue. implemented in one of three ways 1. Zero capacity – no messages are queued on a link. Sender is blocked, no message is waiting, nothing is stored. 2. Bounded capacity – finite length of n messages Sender must wait if link full 3. Unbounded capacity – infinite length Sender never waits
- 23. Thread A thread is a flow of execution through the process code, with its own program counter that keeps track of which instruction to execute next, system registers which hold its current working variables, and a stack which contains the execution history. ... A thread is also called a lightweight process.
- 25. Benefits of Multithreading Responsiveness – may allow continued execution if part of process is blocked, especially important for user interfaces Resource Sharing – threads share resources of process, easier than shared memory or message passing , share code and data . Economy – cheaper than process creation, thread switching lowers cost than context switching Scalability – process run concurrently and hence process complete quicker
- 26. Multithreading Models User thread – supported above the kernel and managed without kernel support Kernel thread – supported and managed directly by the os Relationship between user thread and kernel thread exist There are 3 common ways in establishing relationship Many-to-One One-to-One Many-to-Many
- 27. Many-to-One Many user-level threads mapped to single kernel thread One thread blocking causes all to block Thread management is done in user level Multiple threads may not run in parallel on system because only one may be in kernel at a time Few systems currently use this model
- 28. One-to-One Each user-level thread maps to kernel thread Creating a user-level thread creates a kernel thread If one send block message other thread works that increase concurrency. Whenever you are creating user thread a kernel thread need to be created. If you have 4processor and 5 threads need to run at a time that could not work.
- 29. Many-to-Many Model More kernel thread can be mapped with same or lesser kernel thread. Kernel thread is associated with particular application. Developer create more user thread and made to run parallel with kernel Thread perform blocking call, kernel set another thread to work for execution.