International Business Machines Corporation

Benjamin Lee Goodman

John Steven Dodson

Jeffrey A Stuecheli

Stephen J Powell

Mark Andrew Brittain

Ryan Scott Haraden

A method for performing refresh operations on a rank of memory devices is disclosed. After the completion of a memory operation, a determination is made whether or not a refresh backlog count value is less than a predetermined value and the rank of memory devices is being powered down. If the refresh backlog count value is less than the predetermined value and the rank of memory devices is being powered down, an Idle Count threshold value is set to a maximum value such that a refresh operation will be performed after a maximum delay time. If the refresh backlog count value is not less than the predetermined value or the rank of memory devices is not in a powered down state, the Idle Count threshold value is set based on the slope of an Idle Delay Function such that a refresh operation will be performed accordingly.

Method for scheduling memory refresh operations including power states

The disclosure relates to a method and apparatus to efficiently address livelock in a multi-processor system. In one embodiment, the disclosure is directed to a method for preventing a system bus livelock in a system having a plurality of processors communicating respectively through a plurality of bus masters to a plurality of IO Controllers across a system bus by: receiving at an MMIO state machine a plurality of snoop commands issued from the plurality of processors, identifying a first processor and a second processor from the plurality of processors, each of the first processor and the second processor having a first number of snoop commands in the input queue and a second number of responses in the output queue, the first number and the second number exceeding a threshold; issuing a burst prevention response to the first processor and the second process.

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Cedar Park, TX, United States of America

Benjamin Lee Goodman