Tunable NOOP Lookahead Algorithm
Original Publication Date: 1989-Apr-01
Included in the Prior Art Database: 2005-Jan-27
An algorithm enhances the performance of an I/O Processor (IOP), implementing a System/370 I/O Architecture to Intelligent Peripheral Interface (IPI-3) I/O control interface, for those operations defined by Channel Command Word (CCW) chains ending in NOOP CCWs. Certain applications commonly place either a NOOP CCW or a TIC-to-TIC+8 - NOOP CCW group at the end of the I/O CCW Chains, thus making these types of operation chains critical to overall system performance. Performance of these CCW chain types is impacted due to additional logical level (Image Omitted) control at the IPI-3 device interface, as well as overhead for the fetch and validation of the additional CCWs.