Method and apparatus for response modes in a pipelined environment

• US 20020184421A1
• Filed: 06/01/2001
• Published: 12/05/2002
• Est. Priority Date: 06/01/2001
• Status: Active Grant

• Current Assignee: META Platforms Technologies LLC (Meta Platforms, Inc. (f/k/a Facebook, Inc.))
• Original Assignee: Sonics Incorporated (Meta Platforms, Inc. (f/k/a Facebook, Inc.))
• Inventors: Weber, Wolf-Dietrich, Wingard, Drew E., Tomlinson, Jay S.
• Granted Patent: US 6,785,753 B2
• Time in Patent Office: Days
• US Class Current: 710/107
• CPC Class Codes: G06F 13/4226 with asynchronous protocol

Abstract

A pipelined network is disclosed which provides for at least one mode to control the state of a response flag and when the target device is unable to respond to an initiator device request.

Claims

1. A pipelined network comprising:

at least one initiator device configured to issue requests;

at least one target device coupled to receive requests from at least one initiator device;

a target device configured to receive the request; and

bus signal lines comprising lines to issue requests and responses to requests between initiator devices and target devices and a response flag coupled between at least one target device and at least one initiator device;

said target device comprising logic to respond to the request comprising;

a first mode wherein a no-response-available NRA response is selectively issued if there is no space available in the target device to service the request and a response flag is set to a first state when space is available in the target device to service the request;

a second mode wherein the NRA response is selectively issued if there is no space available in the target device to service the request or the target device is busy and the response flag is set to the first state if space is available in the target device to service the request and the target device is not busy;

a third mode wherein the response flag is set to the first state and the NRA response is selectively issued; and

control logic to select the mode to utilize an NRA response and response flag with respect to an initiator device when a target device is unavailable to service the initiator device request.

2. The pipelined network as set forth in claim 1, wherein the control logic is selected from the group consisting of static control, program controlled and hardwired controlled.

3. The pipeline as set forth in claim 1, wherein the logic comprises response logic configured to issue a NRA response and a response flag logic configured to selectively place the response flag in the first state or the second state.

4. The pipeline as set forth in claim 3, wherein the logic further comprises a fourth mode wherein an NRA is selectively issued and the response flag is set to the first state if an early-flow-control mode is in a first state, and a fifth mode wherein an NRA response is selectively issued and the response flag is set to the first state.

5. The pipeline as set forth in claim 4, wherein the control logic selects one of the first, second and third modes, one of the fourth and fifth modes and logically combines the states of the response flag corresponding to the selected modes to generate a response flag received by the at least one initiator device.

6. A pipelined network comprising:

at least one initiator device configured to issue requests;

at least one target device coupled to receive requests from at least one initiator device;

a target device configured to receive the request; and

bus signal lines comprising lines to issue requests and responses to requests between initiator devices and target devices and a response flag coupled between at least one target device and at least one initiator device;

said target device comprising logic to respond to the request comprising;

a first mode wherein a no-response-available NRA response is selectively issued when an early-flow-control mode is in an active state and a response flag is set to a first state when an early-flow-control mode is in an inactive state;

a second mode wherein the response flag is set to the first state and the NRA response is selectively issued; and

control logic to select the mode to utilize the NRA and response flag with respect to an initiator device when a target device is unavailable to service the initiator device request.

7. The pipelined network as set forth in claim 6, wherein the control logic is selected from the group consisting of static control, program controlled and hardwired controlled.

8. The pipeline as set forth in claim 6, wherein the logic comprises response logic configured to issue a NRA response and a response flag logic configured to selectively place the response flag in the first state or the second state.

9. A pipelined network comprising:

at least one initiator device configured to issue requests;

at least one target device coupled to receive requests from at least one initiator device;

a target device configured to receive the request; and

bus signal lines comprising lines to issue requests and responses to requests between initiator devices and target devices and a response flag coupled between at least one target device and at least one initiator device;

said target device comprising logic to respond to the request comprising;

a first mode wherein a no-response-available NRA response is selectively issued and a response flag is set to a first state when a first condition exists;

a second mode wherein an NRA response is selectively issued and the response flag is set to the first state when a second condition exists; and

control logic to select the mode to utilize an NRA and response flag with respect to an initiator device when a target device is unavailable to service the initiator device request.

10. The pipeline as set forth in claim 9, wherein the control logic logically combines the states of the response flag corresponding to the first and second modes to generate a response flag to be received by the at least one initiator device.

11. The pipeline as set forth in claim 9, wherein the first condition comprises space availability in the target device to service the request and whether the target device is busy.

12. The pipeline as set forth in claim 9, wherein the second condition comprises a state of an early-flow-control.

14. The method as set forth in claim 13, wherein selecting is performed at a time selected from the group consisting of at run-time and at network configuration.

15. The method as set forth in claim 13, further comprising selectively issuing an NRA response and setting the response flag to the first state if an early-flow-control mode is in a first state.

16. The method as set forth in claim 15, further comprising logically combining response flag states of selected responses and to generate a response flag received by the at least one initiator device.

18. The method as set forth in claim 17, wherein selecting is performed at a time selected from the group consisting of at run-time and at network configuration.

20. The method as set forth in claim 18, further comprising logically combining the states of the response flag corresponding to the first and second conditions to generate a response flag to be received by the at least one initiator device.

21. The method as set forth in claim 18, wherein the first condition comprises space availability in the target device to service the request and whether the target device is busy.

22. The method as set forth in claim 18, wherein the second condition comprises a state of an early-flow-control.

13. In a pipelined network comprising at least one initiator device configured to issue requests and at least one target device coupled to receive requests from at least one initiator device, a method for notifying initiator devices that a target device is unavailable to service an initiator device request, the method comprising:

selectively issuing a no-response-available NRA response if space is not available in the target device to service the request and setting a response flag to a first state if space is available in the target device to service the request;

selectively issuing an NRA response if space is not available in the target device to service the request or the target device is busy and setting the response flag to the first state if space is available in the target device to service the request and the target device is not busy;

setting the response flag to the first state and selectively issuing the NRA response; and

selecting a response to issue to an initiator device when a target device is unavailable to service the initiator device request.

17. In a pipelined network comprising at least one initiator device configured to issue requests and at least one target device coupled to receive requests from at least one initiator device, a method for notifying initiator devices that a target device is unavailable to service an initiator device request, the method comprising:

selectively issuing a no-response-available (NRA) response when an early-flow-control condition is in an active state and setting the response flag to a first state if an early-flow-control mode is in an inactive state;

setting the response flag to the first state and selectively issuing the NRA response; and

selecting a response to issue to an initiator device when a target device is unavailable to service the initiator device request.

19. In a pipelined network comprising at least one initiator device configured to issue requests and at least one target device coupled to receive requests from at least one initiator device, a method for notifying initiator devices that a target device is unavailable to service an initiator device request, the method comprising:

selectively issuing a no-response-available NRA response and setting a response flag to a first state when a first condition exists;

selectively issuing an NRA response and setting the response flag to the first state when a second condition exists; and

selecting a response to issue to an initiator device when a target device is unavailable to service the initiator device request.