Unusual QIOs That Require Complex Processing
Simple QIOs, such as read or write requests, are either serviced by the kernel itself or by device drivers. Certain more complicated requests, specifically those involving tape drives and file-level operations, were originally executed by an Ancillary Control Processor (ACP) (a special purpose task with its own address mapping). The Files-11 ODS-1 file system on RSX-11 was provided by a process called F11ACP; originally, the Files-11 ODS-2 file system was provided by F11BACP on VMS, but the functionality of F11BACP was later rearchitected into the VMS kernel to save the overhead of process context switches and is now called an XQP (eXtended Qio Processor).
Read more about this topic: QIO
Famous quotes containing the words unusual, require and/or complex:
“You do not become a “dissident” just because you decide one day to take up this most unusual career. You are thrown into it by your personal sense of responsibility, combined with a complex set of external circumstances. You are cast out of the existing structures and placed in a position of conflict with them. It begins as an attempt to do your work well, and ends with being branded an enemy of society.”
—Václav Havel (b. 1936)
“Criticism occupies the lowest place in the literary hierarchy: as regards form, almost always; and as regards moral value, incontestably. It comes after rhyming games and acrostics, which at least require a certain inventiveness.”
—Gustave Flaubert (1821–1880)
“Young children constantly invent new explanations to account for complex processes. And since their inventions change from week to week, furnishing the “correct” explanation is not quite so important as conveying a willingness to discuss the subject. Become an “askable parent.””
—Ruth Formanek (20th century)