In computer science, a computer is CPU bound (or compute bound) when the time for it to complete a task is determined principally by the speed of the central processor: processor utilization is high, perhaps at 100% usage for many seconds or minutes. Interrupts generated by peripherals may be processed slowly, or indefinitely delayed.
The concept of CPU bound was developed during early computers, when data paths between computer components were simpler, and it was possible to visually see one component working while another was idle. Example components were CPU, tape drives, hard disks, card-readers, and printers. Computers that predominantly used peripherals were characterized as I/O bound. Establishing that a computer is frequently CPU bound implies that upgrading the CPU or optimizing code will improve the overall computer performance.
With the advent of multiple busses, parallel processing, multiprogramming, preemptive scheduling, advanced graphics cards, advanced sound cards and generally, more decentralized loads, it became less likely to identify one particular component as always being a bottleneck. It is likely that a computer's bottleneck shifts rapidly between components. Furthermore, in modern computers it is possible to have 100% CPU utilization with minimal impact to another component. Finally, tasks required of modern computers often emphasize quite different components, so that resolving a bottleneck for one task may not affect the performance of another. For these reasons, upgrading a CPU does not always have a dramatic effect. The concept of being CPU bound is now one of many factors considered in modern computer performance.
Famous quotes containing the word bound:
“Affection, indulgence, and humor alike are powerless against the instinct of children to rebel. It is essential to their minds and their wills as exercise is to their bodies. If they have no reasons, they will invent them, like nations bound on war. It is hard to imagine families limp enough always to be at peace. Wherever there is character there will be conflict. The best that children and parents can hope for is that the wounds of their conflict may not be too deep or too lasting.”
—New York State Division of Youth Newsletter (20th century)