Lecture 7 - 10/13/2011 CNIT 17600 IT Architectures I/O and...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
10/13/2011 1 CNIT 17600 IT Architectures I/O and Storage Systems Lecture 7 Objectives Understand how I/O systems work, including I/O methods and architectures Become familiar with storage media, and the differences in their respective formats Understand how RAID improves disk performance and reliability, and which RAID systems are most useful today Appreciate the role of enterprise storage as a distinct architectural entity Understand the interplay between data communications and storage architectures Become familiar with a variety of widely installed I/O interfaces 2
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
10/13/2011 2 7.1 Introduction Data storage and retrieval is one of the primary functions of computer systems One could easily make the argument that computers are more useful to us as data storage and retrieval devices than they are as computational machines All computers have I/O devices connected to them to achieve high performance, I/O should be kept to a minimum In studying I/O, we seek to understand the different types of I/O devices as well as how they work 3 7.2 I/O and Performance Sluggish I/O throughput can have a ripple effect, dragging down overall system performance This is especially true when virtual memory is involved The fastest processor in the world is of little use if it spends most of its time waiting for data If we really understand what’s happening in a computer system we can make the “best possible” use of its resources 4
Background image of page 2
10/13/2011 3 7.3 Amdahl’s Law The overall performance of a system is a result of the interaction of ALL of its components required for a specific process System performance is most effectively improved when the performance of the most heavily used components is improved This idea is quantified by Amdahl’s Law: 5 where S is the overall speedup; f is the fraction of work performed by a faster component; and k is the speedup of the faster component 7.4 I/O Architectures We define input/output as a subsystem of components that moves coded data between external devices and a host system I/O subsystems include: Blocks of main memory that are devoted to I/O functions Buses that move data into and out of the system Control modules in the host and in peripheral devices Interfaces to external components such as keyboards and disks Cabling or communications links between the host system and its peripherals 6
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
10/13/2011 4 7.4 I/O Architectures This is a model I/O configuration 7 7.4 I/O Architectures I/O can be controlled in five general ways Programmed I/O reserves a register for each I/O device. Each register is continually polled to detect data arrival Interrupt-Driven I/O allows the CPU to do other things until I/O is requested Memory-Mapped I/O shares memory address space between I/O devices and program memory Direct Memory Access ( DMA ) offloads I/O processing to a special-purpose chip that takes care of the details Channel I/O uses dedicated I/O processors 8
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/30/2012 for the course CNIT 176 taught by Professor Hansen during the Fall '09 term at Purdue University-West Lafayette.

Page1 / 42

Lecture 7 - 10/13/2011 CNIT 17600 IT Architectures I/O and...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online