Browse Prior Art Database

Prevention of Low Priority Lockout

IP.com Disclosure Number: IPCOM000040857D
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Geiger, SP: AUTHOR [+3]

Abstract

Normally, interrupt and priority of tasks are ordered from a h priority to a low priority ranking. This results in servicing the most critical tasks with the highest priority first while other lower priority tasks await completion of the higher priority tasks. In some cases, high occurrence of high priority tasks results in the lower priority tasks being locked-out such that they will never be serviced. To overcome this, a hang detector at the highest priority level 0 monitors the performance of level 1 which is the most active priority level. When the time-out mechanism monitoring level 1 tasks times out, level 0 will turn priority over to lower level tasks such as level X and set a hang detector with a priority level 1.

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Prevention of Low Priority Lockout

Normally, interrupt and priority of tasks are ordered from a h priority to a low priority ranking. This results in servicing the most critical tasks with the highest priority first while other lower priority tasks await completion of the higher priority tasks. In some cases, high occurrence of high priority tasks results in the lower priority tasks being locked-out such that they will never be serviced. To overcome this, a hang detector at the highest priority level 0 monitors the performance of level 1 which is the most active priority level. When the time-out mechanism monitoring level 1 tasks times out, level 0 will turn priority over to lower level tasks such as level X and set a hang detector with a priority level 1. If the level 1 hang detector times out before operation has returned to level 1 tasks, it stops performance of lower priority tasks and starts the processing of level 1 priority.

Disclosed anonymously

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