Browse Prior Art Database

Improvement of Interrupt Controller Performance by Fake Local Memory Acknowledge Signal

IP.com Disclosure Number: IPCOM000043566D
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 3 page(s) / 40K

Publishing Venue

IBM

Related People

Hung, TC: AUTHOR

Abstract

To improve performance of an interrupt controller in a disk-based system, the disk adapter process, the disk interrupt service routine and physical format of the disk itself are designed such that the disk interrupt service routine will use as little time as possible. More specifically, a fake local memory acknowledge signal is used in combination with single-sector commands and a two-sector interleave scheme, whereby the lower priority interrupt levels will not be masked off for a long period of time by the disk local memory request interrupts. The disk adapter transfers data to and from the local memory (LM) within a system memory via a direct memory access (DMA) controller. There are two kinds of disk interrupts, i.e., normal command end interrupt and LM request interrupt.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 52% of the total text.

Page 1 of 3

Improvement of Interrupt Controller Performance by Fake Local Memory Acknowledge Signal

To improve performance of an interrupt controller in a disk-based system, the disk adapter process, the disk interrupt service routine and physical format of the disk itself are designed such that the disk interrupt service routine will use as little time as possible. More specifically, a fake local memory acknowledge signal is used in combination with single-sector commands and a two-sector interleave scheme, whereby the lower priority interrupt levels will not be masked off for a long period of time by the disk local memory request interrupts. The disk adapter transfers data to and from the local memory (LM) within a system memory via a direct memory access (DMA) controller. There are two kinds of disk interrupts,
i.e., normal command end interrupt and LM request interrupt. The LM request interrupt is used by the disk adapter to signal to the system software that LM had been filled (during a read command), or fill LM for the next sector to be written to the disk (during a write command). In either case, when interrupted by the hardware, the software is supposed to move data from LM to the user buffer (during a read command) or to move data from the user buffer into LM (during a write command). Then, an acknowledge signal is issued by the interrupt software to the disk adapter, indicating LM transfer is completed. In the case of multi-sector read/write commands, LM request interrupts will occur until all the required sectors are read/written and, subsequently thereto, the normal command end interrupt will occur to transfer status of the executed command. In the contemplated disk-based system, the disk interrupt service routine is assumed to run on interrupt level 2. When the disk interrupt service routine is invoked by the interrupt service driver module, interrupt level 2 and all the lower interrupt levels are masked off. Thus, if level 2 interrupt service routine has to move data to/from LM from/to the user buffer, the lower interrupt levels will be masked off for a long period of time. To avoid the performance of the interrupt controller to be degraded in this way, the present arrangement does use a fake LM acknowledge signal...