Friday, February 24, 2012

ANSWERS FOR BSC-IT


rQ: what is diff/advantage of layered approach over monolithic architecture.
The monolithic kernel is the operating system and offers all the system calls for the user.the monolithic approach of OS offered services by using commands &syntaxes. The main drawback of monolithic approach is the poor design.CPU remains idle most of the time.

Layered model what is based to the microkernel idea to have a tiny microkernel and OS. But instead   of running every service alone distributes their functions to other layers. Every layer uses lower level layer functions and offers owns for others top of it. The microkernel controls all the layers.

Q: explain reader’s writer’s problem?
Readers-writers problems are examples of a common computing problem in concurrency. The two problems deal with situations in which many threadsmust access the same shared memory at one time, some reading and some writing, with the natural constraint that no process may access the share for reading or writing while another process is in the act of writing to it. (In particular, it is allowed for two or more readers to access the share at the same time.) A readers-writer lock is a data structure that solves one or more of the readers-writers problems.

Q: define/what is Dynamic Loading?
A:Dynamic loading is a mechanism by which a computer program can, at run time, load a library (or other binary) into memory, retrieve the addresses of functions and variables contained in the library, execute those functions or access those variables, and unload the library from memory
Q: what is the need of process synchronization?
 Process synchronization refers to the idea that multiple processes are to join up or handshake at a certain point, so as to reach an agreement or commit to a certain sequence of action. Because in concurrent environment’s resources are shared by multiple processes, due to this complexity sync is required to avoid critical sections/deadlocks.

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