Nt1310 Unit 4

manages to put two pointers to the PCB of his/her process with the intention that it can run twice as

slowest process and the slowest process controls the rate of system production. In order to maximize

Linux operating system is using virtual memory to support programs running in the system. The virtual memory provides lots of optimal ways to maximize the memory mapping and utilization. The virtual memory can allocate much more memory to processes than its actual physical memory size. Linux provides virtual memory great support to allow the processes running in the system, such as mapping the process’s memory to physical memory (Arora, 2012).

1) Short-term scheduling: It selects from jobs in memory, those jobs which are ready to execute, and allocates the CPU to one of them. CPU selects

To improve the quality of services and maintaining the efficiency and fairness among the jobs the scheduler

Although it is ideal to have each task started and finished in the earliest period, this situation may not be found in real cases. In most of time, the resource required to launching multiple tasks is greater than the maximum available resources. Consequently, some tasks have to be delayed to start after others are finished.

In reality, there are limited resources, so there are dependencies not shown in the charts. E.g. if only one person is available to work on the shed project, the siding and roofing tasks must be done in serial, due to the resource constraint. SAPM Spring 2006: Project Management 12 Crashing/Fast tracking If the critical path is still not fast enough, it’s possible to shorten the duration by changing some assumptions. E.g.:

processes. There are two different scheduling: real time and normal, for handling large data processes performance balance and sharing CPU equally in the system. In the scheduling of Kernel, each process has a priority value which ranges from 1 to 139. 1 is the highest priority level. 139 is the lowest priority level. The real time priorities range from 1 to 99 and the normal priorities range from 100 to 139. The smaller number of priority value, the priority is higher. All real time programs have a higher priority than normal programs in the system.

While using your computer you generally ask it to do more than one thing at a time. For the OS to do this it slices a piece of it’s time for each task, that requires the processors time. For example, you may be printing a paper, chatting with friends, watching a movie on your computer, all at the same time. It is called multitasking. To provide seamless multitasking, the OS controls the timing of events the processor works on.

If a process took 45 minutes then the user would have to run 2 blocks simultaneously, taking up 1 hour, this means 15 minutes would be wasted, as the process wouldn’t actually take that long. This means that running a number of processes would take too long. This is considered Phase 1 of Operating systems and is called Serial Processing

Each program is provided with a default process heap, but a process may optionally allocate any number of additional heaps, if more storage is needed. The heap functions will manage their virtual memory usage automatically, and therefore heaps can be set to grow if they are being filled up with data. If a heap is allowed to grow automatically, the heap functions will automatically allocate additional pages as needed. On the x86 architecture the heap grows in size towards higher memory addresses.

Previously, UNIX systems used batch jobs, which run a process until it is finished and then the next process will run [8]. What UNIX used is known as “non-preemptive scheduling” [8]. After years, preemptive scheduling was used to run processes in parallel by switching between them [8].

Distributes the workload over different processors and input/output devices. It can handle a large number of users.

Multithreading: Multithreading means running number of threads at the same given time. Usually, this term is used when we talk about single processes which use more than one thread. So, at the level of CPU, one thread is running at one time only, but at the OS level, multiple threads or processes can be at running state which means that they will be periodically scheduled to run on the processor. When we allude to a running thread or procedure, we by and

processor to the slowest memory components at a reasonable cost. It maintains the locality of information and support