公开(公告)号：DE3585970D1

公开(公告)日：1992-06-11

申请号：DE3585970

申请日：1985-06-19

Applicant: IBM

Inventor： CHIESA GEORGE LOUIS ,  KRYGOWSKI MATTHEW ANTHONY ,  MESSINA BENEDICTO UMBERTO ,  PAPANASTASIOU THEODORE ATHANAS

IPC: G06F15/16 ,  G06F12/08 ,  G06F13/16 ,  G06F13/18

Abstract: A fast path (comprising control and data busses) directly connects between a storage controller (18) in a main storage (21) and a requestor (CPU). The fast path (12) is in parallel with the bus path (11, 16, 14) normally provided through the storage hierarchy between the requestor (CPU) and the storage controller (18). The fast path (12) may bypass intermediate levels in the storage hierarchy. The fast path (12) is used at least for fetch requests from the requestor (CPU), since fetch request have been found to comprise the majority of all storage access requests. System efficiency is significantly increased by using at least one fast path (12) in a system to decrease the peak loads on the normal path (11, 16, 14). A requestor (CPU) using the fast path (12) and to the normal path (11, 16, 14) in a system controller element (16). The request through the fast path (12) gets to the main storage (21) before the same request gets through the system controller element, but may be ignored by the storage (21) if the latter is busy. If accepted, the storage (21) can start its accessing controls sooner for a fast path request than if the request is received from the normal path. Every request must use controlled cross-interrogate (17) and storage protect (19) resources. Fast path request SP controls, the SCE priority controls, and by the storage element priority controls. When the accessed data is ready to be sent by the main storage (21), it can be sent to the requestor (CPU) faster on the fast path data bus (12) than on the SCE data bus (11,16,14). The fast path data bus (12) may be used to transfer data for requests ignored from the fast path.