System interconnect dynamic scaling by lane width and operating frequency balancing

• US 9,529,406 B2
• Filed: 06/12/2014
• Issued: 12/27/2016
• Est. Priority Date: 04/16/2014
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Dreps, Daniel Mark, Ferraiolo, Frank D., Haridass, Anand, Jayaraman, Prasanna
• Primary Examiner(s): Rahman, Fahmida
• Application Number:
  US14/302,628
• Publication Number:
  US 20150301576A1
• Time in Patent Office: 929 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 1/324 by lowering clock frequency
• CPC Class Codes: G06F 1/3243 Power saving in microcontroller unit
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

Interface management techniques provide reduced power consumption along with reducing heat and EMI generation in a computer system having multiple interconnected processing units. Physical link layers of external interfaces that interconnect the processing units have dynamically adjustable bandwidth provided by an adjustable width and adjustable operating frequency. The bandwidths may be dynamically adjusted by predicting interface bandwidth requirements. From a required bandwidth, an active width and an operating frequency for the physical link layers are determined and set. The interface is operated according to the determined width and operating frequency.

Claims

1. A method of managing a physical link layer of an external interface connecting processing units within a computer system, the method comprising:

receiving an indication of a required bandwidth for operation of the physical link layer;

from the required bandwidth, determining an active width and operating frequency for the physical link layer that meet the required bandwidth;

setting a current active width of the physical link layer to the determined active width;

setting a current operating frequency of the physical link layer to the determined operating frequency;

operating the physical link layer using the current active width and the current operating frequency;

predicting a future bandwidth requirement for the physical link layer, and wherein the receiving receives the predicted future bandwidth requirement;

determining whether or not a current utilization of the external interface is less than a threshold usage;

evaluating a quality of the predicting;

comparing the quality of the predicting to a threshold quality; and

responsive to determining that the current utilization of the external interface is less than the threshold usage and responsive to the comparing determining that the quality of the predicting is less than the threshold quality, reducing at least one of the current operating frequency or the current active width, wherein the reducing the at least one of the current operating frequency or the current active width comprises reducing the current operating frequency while maintaining the current active width of the physical link layer.

2. The method of claim 1, further comprising determining that the current utilization of the external interface is less than the threshold usage and responsive to the comparing determining that the quality of the predicting is greater than the threshold quality, reducing the current active width while maintaining the current operating frequency of the physical link layer.

3. The method of claim 2, wherein the reducing the current active width is performed periodically by reducing the current active width to zero by powering down the physical link layer of the external interface at periodic intervals and re-powering the physical link layer of the external interface at the end of the periodic intervals.

4. The method of claim 2, further comprising, responsive to determining that the current utilization of the external interface is greater than the threshold usage, setting the current active width to a maximum width and setting the current operating frequency of the physical link layer in conformity with the predicted future bandwidth requirement.

5. The method of claim 4, wherein the predicting predicts a shape of a predicted utilization of the external interface and wherein the setting the current operating frequency controls the current operating frequency in conformity with the shape of the predicted utilization.

6. A method of managing a physical link layer of an external interface connecting processing units within a computer system, the method comprising:

receiving an indication of a required bandwidth for operation of the physical link layer;

from the required bandwidth, determining an active width and operating frequency for the physical link layer that meet the required bandwidth;

setting a current active width of the physical link layer to the determined active width;

setting a current operating frequency of the physical link layer to the determined operating frequency;

operating the physical link layer using the current active width and the current operating frequency;

predicting a future bandwidth requirement for the physical link layer, and wherein the receiving receives the predicted future bandwidth requirement;

determining whether or not a current utilization of the external interface is less than a threshold usage;

evaluating a quality of the predicting;

comparing the quality of the predicting to a threshold quality; and

responsive to determining that the current utilization of the external interface is less than the threshold usage and responsive to the comparing determining that the quality of the predicting is less than the threshold quality, reducing at least one of the current operating frequency or the current active width, wherein the reducing the at least one of the current operating frequency or the current active width comprises reducing the current active width while maintaining the current operating frequency of the physical link layer.