This page was last edited on bangalore city map free download pdf January 2018, at 03:03. How do you execute one program from within another? The execlp call overlays the existing program with the new one , runs that and exits.

The original program gets back control only when an error occurs. A variant of execlp called execvp is used when the number of arguments is not known in advance. What are the various schemes available? One-way communication scheme through which different process can communicate. Message queues can be used between related and unrelated processes running on a machine.

This is the fastest of all IPC schemes. The speed achieved is attributed to the fact that there is no kernel involvement. But this scheme needs synchronization. Various forms of synchronisation are mutexes, condition-variables, read-write locks,     record-locks, and semaphores. What is the difference between Swapping and Paging? Whole process is moved from the swap device to the main memory for execution. Process size must be less than or equal to the available main memory.

It is easier to implementation and overhead to the system. Swapping systems does not handle the memory more flexibly as compared to the paging systems. Only the required memory pages are moved to main memory from the swap device for execution. Process size does not matter.

Gives the concept of the virtual memory. It provides greater flexibility in mapping the virtual address space into the physical memory of the machine. Allows more number of processes to fit in the main memory simultaneously. Allows the greater process size than the available physical memory. Demand paging systems handle the memory more flexibly.