Browse Prior Art Database

Reducing Scrub Interference With Interruptible/Restartable Scrubs

IP.com Disclosure Number: IPCOM000036307D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Hardell, WR: AUTHOR [+4]

Abstract

Disclosed is a means to reduce scrub interference by having scrubs interruptible. Other requests can be serviced between the read and write procedures of a scrub operation. However, the scrub must be restarted if a store occurs to the scrub line or the scrub buffer is modified.

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Reducing Scrub Interference With Interruptible/Restartable Scrubs

Disclosed is a means to reduce scrub interference by having scrubs interruptible. Other requests can be serviced between the read and write procedures of a scrub operation. However, the scrub must be restarted if a store occurs to the scrub line or the scrub buffer is modified.

A scrub operation is made up of a read and a write to main storage. A scrub write (of corrected data) only occurs if a single bit error is detected during the scrub read cycle.

With this scrub method, a high priority memory request may be processed faster by interrupting scrubs between the read and write parts. When a high priority request is serviced between the read and write parts of a scrub, two things can happen: 1) When all other requests are complete, the scrub

will continue. The scrub was only INTERRUPTED.

2) When all other requests are complete, the scrub

must start over with the read part. The scrub

will RESTART.

There are two things that can occur between a scrub read and write that will force the scrub to restart: 1) The data in the scrub buffer can be over-written

(if the scrub buffer is shared).

2) The data in RAM, at the scrub address, can be

modified by a write operation.

When a high priority request is serviced in between the read and write parts of a scrub, the hardware must determine if the scrub was only INTERRUPTED or the scrub must be RESTARTED.

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