Hi, I have several doubts, that is about the basics in operating system, and I w

Question

Hi,

I have several doubts, that is about the basics in operating system, and I wonder if anyone can help:

1- Regarding Memory Paritioning:

A. How to keep track of the free memory blocks in case of using FIXED partitioning. I know that in case of Dynamic Paritioning there is a need for data structures to keep track of the free spaces such as (linked list, tree, and hash tables)

B. Does the internal fragmentation occurs with Dynamic memory partitioning or it is just a problem that occurs with static memory paritioning?

3- Does using Dynamic memory allocation means that dynamic partitioning technique is used?

2- Regarding Periodic Tasks in real time systems,,, I don't understand what kind of tasks belong to this type which is generated at every of time. I need an example in real time system

Thanks in advance,

Explanation / Answer

1A. How to keep track of the free memory blocks in case of using FIXED partitioning. I know that in case of Dynamic Paritioning there is a need for data structures to keep track of the free spaces such as (linked list, tree, and hash tables)

The fixed partitions are the one which are static. these partitioned are handled by the Initial program Load. Initial Program Load is nothing but the boot program. so we can say that the fixed partitions for the programs are decided by the routines(automatic) at the time of the booting based on the memory required for the process and the total memory available. If there are no routines for this , then it would be done by the computer operator manually, who can decide the amount of memory to be granted based on the available memory.

To keep track of free memory ,Bit map method is used. 1 bit is allocated to each fixed partition. if bit is 0 the memory unit is free ,if the bit is 1 the memory unit is allocated.

Linked list of free node is also maintained. A node start address, size and address of the next node is maintained.

1B Does the internal fragmentation occurs with Dynamic memory partitioning or it is just a problem that occurs with static memory paritioning?

Internal Fragmentation is the problem of static memory partiotion but not the problem of dynamic memory partition.There will be no Internal Fragmentation Problem in Dynamic memory partition.

3- Does using Dynamic memory allocation means that dynamic partitioning technique is used?

   Yes,the Dynamic Memory allocation for the process includes dynamic partition techniques.

Periodic Tasks in real time systems

A Real time operating system (RTOS) is an operating system intended to serve real-time application process data as it comes in. that means the application which ever comes in has to be processed immediately.
There are two types of RTOS:
1.Soft- the RTOS that can accept some small or minute delays
2.Hard-the RTOS which are bound to restrictions. which cannot accept even a minute delay. an occurence of delay might lead to hazardous situations.

Periodic Tasks in RTS or RTOS are the tasks which have regular time intervals and hard deadlines. that means these are the tasks which are to be served almost immediately upon the arrival.

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