The obsolescence of look-ahead buffering
H. Lynn Beus · Annual Simulation Symposium · 1975
This paper is concerned with the computer software technique called look-ahead buffering, or multiple buffering. This involves the use of two or more data input or output areas associated with a file or I/O device. These buffers are pre-read or post-written under control of the operating system. Historically there were two reasons for this technique: First, the program using look-ahead buffering was able to complete its operations in less real time. Second, in the early uni-programming systems multiple buffering increased system throughput by increasing resource utilization. Both of these were valid reasons for using the technique in those situations. The question is, whether this is still true in modern multiprogramming systems.At first glance it appears that reason number one is still equally valid in the multiprogramming environment. One factor which might affect this, however, is the increased channel loading and utilization generally found in these systems. Individual I/O requests will frequently have to wait longer for completion, thus counteracting to some extent their lookahead function. The second reason, that of increased throughput, is of even more questionable value in a multiprogramming environment.