⑶ What is the independence of the equipment? Depending on the type of equipment, equipment allocation strategy What? (Exclusive of equipment, shared devices, the virtual device, and SPOOLing system). Disk, for example, the optimized scheduling algorithm? Should consider what factors?
3 channel control block
3, device drivers, to achieve the physical I / O operations;
1, device control block
2, take full advantage of the interruption technology, channel and buffer and improve the parallelism between the ability to work in the CPU and equipment, devices and equipment, to make full use of equipment resources, to improve the efficiency in the use of external devices.
device management tasks:
For multiple procedures, enter the batch job in advance through the input device sent to the disk. The operating result in the output and all temporary disk rather than directly on the output, until a job to get the full results at the end of the line output. (That is, analog input and printers work with the disk to save the content of their work, and then together with the implementation of)
array of selected channel (Block Selector Channal)
2. Interrupt mode Disadvantages:
(3) channel works by transmission of data can be divided into several categories?
device management functions:
(1) the request made by the user needs access to external devices, distribution and management system according to a certain algorithm control, and users do not have the actual device address and control instructions;
l process data is required by the CPU to issue the “start” instruction to start the peripheral devices to prepare data
(1) exclusive equipment; (2) shared equipment; (3) virtual device
virtual equipment conditions
A: There are four major: 1, cycle test I / O modes; 2, the interrupt handler; way of direct memory access (DMA); 4 channel mode
improve system reliability: when a path controller or channel failure and disconnect, you can use other pathways. the
(3) the input process SPi and output process Spo
external device classification (1): system and user system equipment, user equipment
(4) the physical characteristics of the device hardware: the order access equipment, direct access to the equipment
l at a later time, the process scheduler to select the requested and received data process, the process is out of the memory unit agreed to continue working.
device independence: the replacement of the physical device can not affect the normal operation of the user program;
, equipment distribution and recycling;
(4) control and input-output operations < br /> 4, the system device table
disk scheduling in general can use the following algorithm:
1. to improve the speed between the CPU and I / O device does not match the contradictions
virtual device its realization.
buffer means the buffer memory used to temporarily hold data.
byte multiplexer channel (Byte Multiplexor Channal)
l issued a directive to start the process equipment, the process to give up the processor, waiting for input to complete.
1. Data input steps:
according to the different ways of information exchange channel is divided into the following three types:
A: The channel is a hardware mechanism used to control external devices, which is equivalent to a simple function processor.
(1) outlined the channel and the channel control structure.
disk drive scheduling purposes: to reduce the total time of multiple visitors to perform input and output operations, to increase the number of operations of the input and output per unit time, the system efficiency.
(1) block device; character device (2)
controller block
(3) Management
array of multi-channel input and output buffer (Block Multiplexor channal)
interrupt the way (interrupt) is used to control data transfer between peripherals and memory and CPU. This approach requires that the corresponding interrupt request lines between the CPU and the device (or controller), but also allows the device controller control status register interrupt bit.
:
in the general large-scale computer systems, host control of external devices can be divided into three levels, namely, channels, controllers and equipment.
(2) the allocation of equipment and release
:
1) First Come First Served algorithm (FCFS);
A: General equipment for cross connections, and its benefits :
Once the CPU has issued instructions to start the channel, the channel can be independent of the CPU. Channel control of the controller, the controller used to control the circuit part of the equipment. In this way, a channel can be connected to multiple controllers, a controller can be connected to a number of the same type of external device. In the end, the device controller to perform the operation.
(6) according to the data organization: block device, character device
2, the shortest seek time first disk scheduling algorithm (leaf Total Flavonoid Against)
1. SPOOL system components
SPOOLing, peripherals online parallel operation, it is a speed matching technology, is also a virtual device (a physical device simulation of other physical devices, so that during execution of each job only use the virtual device without direct use of the exclusive equipment of the physical. This exclusive technology enables the device into the shared equipment, equipment utilization and system efficiency can be improved).
(5): equipment, the use of physical devices, logical devices pseudo-device
SPOOLing systems are mainly of three parts:
When the mobile arm positioning, if the number of visitors to wait for access to the cylinder, according to the delay time to determine the scheduling of the execution order is called rotation scheduling.
3, the resource allocation point of view classification
1, to provide users with the convenience of external devices, unified interface, in accordance with the requirements of the user and the type of equipment, control equipment, completion of user input input request.
according to the number of buffer system settings, buffer technology is divided into: single buffering, double buffering, buffer and buffer pool
4) one-way scan scheduling algorithm (CSCAN).
disk drive scheduling: multiprogramming system, while the number of visitor requests a disk operation, then the system uses a scheduling policy to decide to wait for the execution order of the visitors, so decided to wait for the disk the order of execution of the work of the visitors is the disk drive scheduling.
(2) equipment can be classified in accordance with the manner in which each classification also includes what?
1, fairness, efficiency
3, device management is to ensure that the multi-process environment, when multiple processes compete for use of equipment, in accordance with the strategy allocation and management of equipment, so that The system can work in an orderly manner.
disk debugging algorithm should consider two basic factors: more
(1) input wells and output wells
1) in a data transmission process, the number of disruptions. This costs a lot of CPU processing time.
3) elevator scheduling algorithm (SCAN);
According to the I / O control, buffer implementation in two ways: one is using a dedicated hardware buffer; the other is in memory set aside a n units dedicated buffer to store the input / output of data. Memory buffer, also known as a software buffer.
(4) What are the external device input, output mode?
(4) for the effective management of the equipment, what kind of data structure?
shifting the arm scheduling algorithm consists of the following four: What is the
(1) equipment assigned tasks?
This article is reproduced, the source and belongs to China University of Science and Technology School of Software the Dianthus all:
(6) in some of the larger system virtual device technology
October 23, 2010 A: Japanese
byte multiplexer channel; select a channel; group channels
(1) What is the operating system management, device management?
in memory to open up two buffers, the input buffer for temporary storage of data sent by the input device, input wells are then transmitted to later; output buffer for temporary sent from the output well data, after the re-transmission sent to the output device.
(3) the characteristics of resources: exclusive equipment, shared equipment, the virtual device
(2) brief channel control device which connection? What are its advantages?
4, an external device interrupt handling;
improve the parallelism of the equipment: the same device, when a path it is connected to a controller or channel is occupied, you can choose another one free path, reducing the time it takes to equipment due to the need to wait for the pathway.
cylinder location specified by the visitors to the scheduling of the execution order of said shift arm scheduling;
(3) equipment management objectives and functions?
process Spi peripheral control of the simulated off-line input, the user request data from the input machine through the input buffer to the input shaft. When the CPU needs to input data directly from the input well read into memory. The Spo process analog line output of the peripheral control the user output data to start with the memory to the output of the well, until the output device idle wells and then output the data through the output buffer to the output device.
A: The goal of the Device Manager:
, management input input buffer;
2
in the organization of data on the device, a first-come first-served disk scheduling algorithm ( FCFS)
3, the virtual device realization principle
(1) of storage devices; (2) the input and output devices
A: To achieve equipment, controllers, channel resource allocation and recovery, system need to record the relevant information. Usually the Device Manager to establish the following data structures to implement effective management.
scanning algorithm (SCAN)
(1) dynamic control and recording equipment status
system security: device allocation can not lead to deadlock.
interrupt (Interrupt) refers to computer during execution, the system occurred in unusual or unexpected need to handle the event, making the CPU to temporarily interrupt the currently executing program and turn the event handler to execute the response. To be disposed of and then returned to the original point of interruption to continue execution or scheduling a new program execution process. The interrupt can generally be divided into software interrupts and hardware interrupts.
(2) maximize the utilization of input and output devices, for example, play the real work in parallel between the host and peripherals, and peripherals, and peripherals. The main use of technology: technology interrupts, DMA technology, channel, buffer technology.
they are opened up two large buffer on disk. Wells of the input analog input offline disk, for the resettlement of the input data I / O devices; output well is the disk when the analog line output, output data for the resettlement of the user program.
(5) to provide equipment to use user interface
A: The equipment assigned tasks in accordance with the strategy assigned the appropriate equipment for the process of applying for equipment, the controller and channel.
computer experts – knowledge of the operating system Detailed (d) Device Manager
(7) data transfer rate: low-speed device, medium-speed equipment, high-speed equipment
l When the input is complete, I / O controller sends an interrupt to the CPU interrupt request line request.
(2) (UNIX or Linux operating system), according to the input and output transmission: character device, block device
2 can reduce the CPU interrupt frequency to relax the restrictions on the interrupt response time
A: 1, according to the operating characteristics of the device.
(2) device allocation should adhere to the principle of what is?
channel channel (channel): a computer system capable of independent completion of the operation of input and output hardware device, also known as the “input and output processor.
disk scheduling is divided into the shift arm scheduling and rotation scheduling.
2) When the device data into the data buffer register and sends an interrupt signal, the CPU has enough time to the next (group) data into the data buffer register before the removal of data. If the peripheral speed is very fast, may cause data loss of the data buffer register.
CPU does not directly operate the peripheral device connection channel (I / O processor), the channel connection device controller, device controller connected devices. CPU only “I / O devices to start, and gives the operating requirements. By the channel to handle input and output issues, done after the report of the CPU.
the DMA stands for Direct Memory Access, which means “direct memory access”. It refers to a high-speed data transfer operations, and allow direct read and write data between external devices and memory, that is, not through the CPU does not need the CPU intervention. The entire data transfer operation is under the control of a DMA controller. CPU in addition to make a little deal with the beginning and end of data transmission in the transmission process, the CPU can carry out other work. Thus, most of the time, CPU and input and output are in parallel operation. Therefore, the entire computer system efficiency is greatly improved.
device management goals and mission equipment management objectives:
A: Device Manager is a computer system in addition to all input and output devices other than the CPU and memory management.
3. improve the condition of parallelism between the CPU and I / O devices
software: the operating system uses multi-channel programming. The
buffer technology is a common means of transmitting information between the two kinds of speed equipment a smooth transfer process. It can increase the peripheral utilization as much as possible so that the peripheral is busy. The main reason for the introduction of buffer can be attributed to the following:
A: The process of application for equipment, shall specify the required equipment categories, rather than specify a specific device, the system based on the current request as well as equipment distribution, an idle equipment and assigned to the application process, select the appropriate category of equipment known as the independence of the equipment.
2) the shortest find time priority scheduling algorithm (leaf Total Flavonoid Against);
hardware conditions: high-capacity disk; interrupt devices and channels; the central processor and channel the ability to work in parallel.
(2) the input buffer and output buffer
the