Compiled by: Jayakumar BalasubramanianWeb: http://www.jwritings.com

Email: b.jayakumar@gmail.com

Introduction Basics of Embedded Systems Program segments The ‘fork()’ system call Concurrent and Iterative servers I/O multiplexing methods Programming using select

Basics of Embedded SystemsDevelopment system TargetCross compilersDevelopment processDevelopment challenges:

Less resources Inter process communication issues Timing problems

Process vs. Threads

Servers and connections Servers:

Iterative servers Concurrent servers

Connections Control connections Data connections

Apartment vs. Bungalow

Process Vs Threads

The fork()

Concurrent servers

Concurrent servers

I/O MultiplexingBlocking I/ONon-blocking I/OI/O multiplexing (Select)Asynchronous I/O Signal driven I/O

Blocking I/O

Non-blocking I/O

I/O Multiplexing

Select() : The I/O Multiplexer

What does it do?This function allows the process to instruct

the kernel to wait for any one of multiple events to occur and to wake up the process only when one or more of these events occurs or when a specified amount of time has passed

The syntax for ‘select()’ int numfds;int numfds; struct timeval timeout; struct timeval timeout; fd_set rfds; fd_set rfds; fd_set wfds; fd_set wfds; fd_set efds; fd_set efds; s=select (numfds, &rfds, &wfds, &exfds, &timeout); s=select (numfds, &rfds, &wfds, &exfds, &timeout);

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