ARBITER, CROSSBAR, REQUEST SELECTION METHOD AND INFORMATION PROCESSING DEVICE

• US 20080043767A1
• Filed: 04/26/2007
• Published: 02/21/2008
• Est. Priority Date: 08/18/2006
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Kinoshita, Takayuki, Ichimiya, Junji, Itozawa, Shintarou
• Granted Patent: US 7,830,902 B2
• Time in Patent Office: Days
• US Class Current: 370/412
• CPC Class Codes: G06F 13/1657 Access to multiple memories
• CPC Class Codes: G06F 13/364 using independent requests or grants, e.g. using separated request and grant lines
• CPC Class Codes: G06F 13/4022 using switching circuits, e.g. switching matrix, connection or expansion network G06F13/4009 takes precedence

Abstract

A plurality of units (processing units) connected to a crossbar are divided into a plurality of groups and one is selected from requests selected for each group according to priority among the groups that changes at prescribed time intervals. Thus, the number of times per unit time requests issued from units belonging to a group whose priority is improved at the prescribed time intervals can be maintained over a certain value regardless of a request state.

Claims

1. An arbiter for selecting one from requests issued by each of a plurality of units that are mounted on and connected to a crossbar, comprising:

first request selection part for selecting one from requests issued by each of the units belonging to the same one of a plurality of groups respectively;

second request selection part for selecting one from the requests selected for each of the groups by the first request selection part;

selection control part for enabling the second request selection part to select requests according to predetermined priority among the plurality of groups; and

the priority among the groups can be changed at prescribed time intervals.

2. The arbiter according to claim 1, wherein

when one or more system boards mounting one or more CPUs and one or more IO units for connection with peripheral devices are connected to the crossbar as the units, the plurality of groups are divided into two of a first group to which only the system boards belong and a second group to which only the IO units belong, and

the selection control part temporarily makes priority of the first group higher than that of the second group.

3. An arbiter for selecting one from requests issued by each of a plurality of units that are mounted on and connected to a crossbar, comprising:

first request selection part for selecting one from requests issued by each of the units belonging to the same one of a plurality of groups respectively;

second request selection part for selecting one from the requests selected for each of the groups by the first request selection part;

selection control part for enabling the second request selection part to select requests according to predetermined priority among the plurality of groups; and

the priority among the groups can be dynamically changed.

4. The arbiter according to claim 3, wherein

the selection control part comprises a plurality of counting part for counting a number of times the request is issued for each of the groups, the priority is dynamically changed on the basis of the number of times counted for each group by the plurality of counting part.

5. The arbiter according to claim 4, wherein

the selection control part gives top priority to a group, the number of times counted by the plurality of counting part is a minimum.

6. The arbiter according to claim 3, wherein

when one or more system boards mounting one or more CPUs and one or more IO units for connection with peripheral devices are connected to the crossbar as the units, the plurality of groups are divided into two of a first group to which only the system boards belong and a second group to which only the IO units belong.

7. A crossbar to which a plurality of units are connected, comprising:

first request selection part for selecting one from requests issued by each of the units belonging to the same group for each of the groups obtained by dividing the plurality of units;

second request selection part for selecting one from the requests selected for each of the groups by the first request selection part; and

selection control part for enabling the second request selection part to select requests according to priority among the groups that change at predetermined time intervals.

8. The arbiter according to claim 7, wherein

when one or more system boards mounting one or more CPUs and one or more IO units for connection with peripheral devices are connected to the crossbar as the units, the plurality of groups are divided into two of a first group to which only the system boards belong and a second group to which only the IO units belong.

9. A crossbar to which a plurality of units are connected, comprising:

first request selection part for selecting one from requests issued by each of the units belonging to the same group for each of the groups obtained by dividing the plurality of units;

second request selection part for selecting one from the requests selected for each of the groups by the first request selection part; and

selection control part for dynamically changing priority among the groups and enabling the second request selection part to select requests according to the priority.

10. The crossbar according to claim 9, wherein

when one or more system boards mounting one or more CPUs and one or more IO units for connection with peripheral devices are connected to the crossbar as the units, the plurality of groups are divided into two of a first group to which only the system boards belong and a second group to which only the IO units belong.

11. A request selection method for enabling a crossbar to which each of a plurality of units are connected to select one from requests issued by the plurality of units, comprising:

selecting one from requests issued by each of the units belonging to the same group for each of the groups obtained by dividing the plurality of units; and

selecting one from the requests selected for each of the groups according to priority among the groups which changes at predetermined time intervals.

12. The request selection method according to claim 11, wherein

when one or more system boards mounting one or more CPUs and one or more IO units for connection with peripheral devices are connected to the crossbar as the units, the plurality of groups are divided into two of a first group to which only the system boards belong and a second group to which only the IO units belong.

13. A request selection method for enabling a crossbar to which each of a plurality of units are connected to select one from requests issued by the plurality of units, comprising:

selecting one from requests issued by each of the units belonging to the same group for each of the groups obtained by dividing the plurality of units; and

dynamically changing priority among the groups and selecting one from the requests selected for each of the groups according to the priority.

14. The request selection method according to claim 13, wherein

when one or more system boards mounting one or more CPUs and one or more IO units for connection with peripheral devices are connected to the crossbar as the units, the plurality of groups are divided into two of a first group to which only the system boards belong and a second group to which only the IO units belong.

15. An information processing device, comprising:

a plurality of processing units which is divided into a plurality of groups, each for issuing requests;

first request selection part for arbitrating the requests issued from the plurality of processing units and selecting one from the requests issued from the processing units belonging to the same group;

second request selection part for selecting one from the requests selected for each of the groups by the first request selection part;

selection control part for enabling the second request selection part to select requests according to predetermined priority among the plurality of groups; and

the priority among the groups can be dynamically changed.