# US 2015/0178239 A1 · Command rate configuration in data processing system

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- Number: US 2015/0178239 A1
- Document ID: US20150178239A1
- Status: Published application
- Kind: A1
- Application number: 14/311,508
- Filed: 2014-06-23
- Published: 2015-06-25
- Earliest claimed: 2013-12-20
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: GUY L. GUTHRIE; DAVID J. KROLAK; CHARLES F. MARINO; PRAVEEN S. REDDY; MICHAEL S. SIEGEL
- Web page: https://patentgrep.com/patent/US20150178239A1

## CPC

- G06F 13/4208: {being a system bus, e.g. VME bus, Futurebus, Multibus}
- G06F 3/00: Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F 9/54: Interprogram communication
- G06F 13/36: for access to common bus or bus system
- G06F 13/4022: {using switching circuits, e.g. switching matrix, connection or expansion network (G06F13/4009 takes precedence)}
- G06F 15/00: Digital computers in general (details G06F1/00 – G06F13/00); Data processing equipment in general
- Y02D 10/00: Energy efficient computing, e.g. low power processors, power management or thermal management
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE

## Abstract

In one or more embodiments, one or more systems, devices, methods, and/or processes described can continually increase a command rate of an interconnect if one or more requests to lower the command rate are not received within one or more periods of time. In one example, the command rate can be set to a fastest level. In another example, the command rate can be incrementally increased over periods of time. If a request to lower the command rate is received, the command rate can be set to a reference level or can be decremented to one slower rate level. In one or more embodiments, the one or more requests to lower the command rate can be based on at least one of an issue rate of speculative commands and a number of overcommit failures, among others.

## Claims

### Claim 1

A method of operating a data processing system that includes an interconnect and a plurality of processor units coupled to the interconnect, the method comprising:
determining that a request to change a current command rate of a fabric arbiter of the interconnect was not received within a first sample window;
determining whether a incremental rate increase is to be utilized;
in response to determining the incremental rate increase is to be utilized, configuring a first new command rate to a command rate level incrementally greater than the current command rate;
in response to determining the incremental rate increase is not to be utilized, configuring the first new command rate to a predetermined command rate greater than the current command rate; and
issuing, to the fabric arbiter of the interconnect, a first change rate command that includes the first new command rate.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
determining whether or not an ascent time has transpired; and
wherein configuring the first new command rate to the command rate level incrementally greater than the current command rate is performed only in response to determining that the ascent time has transpired and otherwise refraining from configuring the first new command rate to the command rate level incrementally greater than the current command rate until at least a second sample window.

### Claim 3 (depends on 1)

The method of claim 1, further comprising:
determining that a request to change the command rate was received within a second sample window;
determining if the current command rate is less than a reference command rate;
in response to determining the current command rate is less than a reference command rate, configuring a second new command rate to the reference level;
in response to determining the current command rate is not less than a reference command rate, configuring the second new command rate to a command rate level incrementally less than the current rate level; and
issuing, to the fabric arbiter of the interconnect, a second change rate command that includes the second new command rate.

### Claim 4 (depends on 3)

The method of claim 3, wherein the request to change the command rate is based on a number of overcommit failures.

### Claim 5 (depends on 3)

The method of claim 3, wherein the request to change the command rate is based on an issue rate of speculative commands.

### Claim 6 (depends on 1)

The method of claim 1, wherein the first change rate command is associated with one of a group scope, a remote group scope, and a system scope.

### Claim 7 (depends on 1)

The method of claim 1, wherein the data processing system includes a symmetric multiprocessor system.