US 7,454,648 B2 · System and method for calibrating a time of day clock in a computing system node provided in a multi-node network

Abstract

A system, method and computer program product for calibrating a Time Of Day (TOD)-clock in a computing system node provided in a multi-node network. The network comprises an infrastructure of computing devices each having a physical clock providing a time base for executing operations that is stepped to a common oscillator. The system implements steps for obtaining samples of timing values of a computing device in the network, the values including a physical clock value maintained at that device and a TOD-offset value; computing an oscillator skew value from the samples; setting a fine steering rate value as equal to the opposite of the computed oscillator skew value; and, utilizing the fine steering rate value to adjust the physical clock value and correct for potential oscillator skew errors occurring in the oscillator crystal at the computing device.

Claims20

Dependent claims

A method for calibrating a Time Of Day (TOD)-clock in a computing system node provided in a multi-node network, said network comprising an infrastructure of computing devices each having a physical clock providing a time base for executing operations that is stepped to a common oscillator, said method comprising:

a) obtaining samples of timing values of a computing device in said network, said values including a physical clock value maintained at that device and a TOD-offset-aggregate value;
b) computing an oscillator skew value from said samples;
c) setting a fine steering rate value as equal to the opposite of the computed oscillator skew value;
and,
d) utilizing said fine steering rate value to adjust said physical clock value and correct for potential oscillator skew errors occurring in the oscillator crystal at said computing device,
wherein said TOD-offset-aggregate value comprises:
a TOD-offset value component that is added to a physical clock value to obtain a basic machine TOD clock at that node, a primary reference time (PRT) offset value component, and a Coordinated Server Time (CST) offset value component maintained at a computing device at that node.

4 more elements

An apparatus for calibrating a Time Of Day (TOD)-clock in a computing system node provided in a multi-node network, said network comprising an infrastructure of computing devices each having a physical clock providing a time base for executing operations that is stepped to a common oscillator, said apparatus comprising:

means for obtaining samples of timing values of a computing device in said network, said values including a physical clock value maintained at that device and a TOD-offset-aggregate value;
means for computing an oscillator skew value from said samples;
and,
a means for setting a fine steering rate value as equal to the opposite of the computed oscillator skew value, said means utilizing said fine steering rate value to adjust said physical clock value and correct for potential oscillator skew errors occurring in the oscillator crystal at said computing device,
wherein said TOD-offset-aggregate value comprises:
a TOD-offset value component that is added to a physical clock value to obtain a basic machine TOD clock at that node, a primary reference time (PRT) offset value component, and a Coordinated Server Time (CST) offset value component maintained at a computing device at that node.

3 more elements

Dependencies are inferred from the claim text.

System and method for calibrating a time of day clock in a computing system node provided in a multi-node network

Life of this patent

System and method for calibrating a time of day clock in a computing system node provided in a multi-node network

Life of this patent

Abstract

Claims20