Device Management in Operating System
Device Management in Operating System – Several resources may require for a process to execute such as main memory, access to files, disk drives and so on. Resource can be granted if they are available and control can be reverted to the processor. Otherwise process will have to wait until the adequate resources are available. System has several devices and to manage these physical or virtual devices operating system needs a separate program to communicate these devices which is called ad device controller. It also checks whether requested device is available or not.
There are several resources controlled by the operating system which can be supposed of as devices, some of these are physical devices for example tapes and some are taken as virtual or abstract devices for example files. In case if there are multiple users of the system then the system may require to first request the device to confirm exclusive use of it. After implementation of the task for which the device was required will release it. This kind of functions has similar to the open and close system call for files. There are other operating systems that allow unmanaged access to devices which can be a cause of hazard or deadlock condition.
Once the requested device allocated then it can be read, write and possibly reposition the device same as can be done in case of files. Similarity between files and I/O devices is so prodigious that several operating systems including UNIX merge these two into a joined file which is called as device structure. A set of system calls is used on devices and files. Sometimes I/O devices are recognized by directory placement, special file name or file attributes. The user interface also make devices and files seems to be similar however the core system calls are dissimilar, this an example of the many design decisions that go into making a user interface and operating system. Operating system manages devices communication by their corresponding device drivers. Operating system performs the following activates to manage the devices
- It decides that which process and when gets the device for how much time.
- It holds track of all the devices, I/O controller is used to perform this task.
- It allocates the devices in convenient and efficient manner.
- Deallocate the devices which are no longer required for a task.