Influence of Input/output Operations on Processor Performance

Nowadays, computers are frequently equipped with peripherals that transfer great amounts of data between them and the system memory using direct memory access techniques (i.e., digital cameras, high speed networks, . . . ). Those peripherals prevent the processor from accessing system memory for significant periods of time (i.e., while they are communicating with system memory in order to send or receive data blocks). In this paper we study the negative effects that I/O operations from computer peripherals have on processor performance. With the help of a set of routines (SMPL) used to make discrete event simulators, we have developed a configurable software that simulates a computer processor and main memory as well as the I/O scenarios where the periph-erals operate. This software has been used to analyze the performance of four different processors in four I/O scenarios: video capture, video capture and playback, high speed network, and serial transmission

A New Hierarchical Disk Architecture

Large RAM caches are generally used to speed up disk accesses. Such caches more effectively improve read performance than write performance, since write requests must be frequently written into disks to protect them from data loss or damage due to system failures. While Non-volatile RAM (NVRAM) caches can be used to improve write performance, large NVRAM caches are too expensive for many applications. This paper presents a new disk cache architecture called DCD, Disk Caching Disks. DCD takes the advantage of large data transfer sizes and uses inexpensive disk space to provide a high-performance, low-cost and reliable caching solution