Bus system providing dynamic control of pipeline depth for a multi-agent computer

• US 5,761,449 A
• Filed: 06/06/1997
• Issued: 06/02/1998
• Est. Priority Date: 03/01/1994
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Rhodehamel, Michael, Sarangdhar, Nitin, Fisch, Matthew
• Primary Examiner(s): Ray, Gopal C.
• Application Number:
  US08/871,593
• Time in Patent Office: 361 Days
• Field of Search: 395/670-672, 395/675, 395/286, 395/800.41
• US Class Current: 710/106
• CPC Class Codes: G06F 13/387 for adaptation of different data processing systems to different peripheral devices, e.g. protocol converters for incompatible systems, open system
• CPC Class Codes: G06F 13/4027 using bus bridges G06F13/4022 takes precedence
• CPC Class Codes: G06F 13/4217 with synchronous protocol

Abstract

A bus system for a computer having multiple agents provides a mechanism for unilaterally and dynamically limiting the pipelining depth. Each agent includes a state machine which indicates whether the bus is in a throttled state, a stalled state or a free state. When in a free state, an agent having control of the bus may transmit any number of bus transactions and the depth of the pipeline may therefore increase. In the throttled state, the agent may transmit only a single bus transaction from the throttled state. The state machine always transitions either to the stalled state or to the free state. In the stalled state, no agents may transmit transactions onto the bus and the depth of the pipeline therefore cannot increase and instead may decrease with time as previously issued transactions are drained from the bus.

Claims

1. A system comprising:

a plurality of interconnected agents;

means for transmitting pipelined bus transactions on a bus with a current pipeline depth varying up to a current maximum pipeline depth; and

means within each of the plurality of interconnected agents connected to the bus for unilaterally and dynamically changing the current maximum pipeline depth.

2. A system comprising:

a plurality of interconnected agents;

a bus; and

a bus controller, within each of the plurality of interconnected agents connected to the bus, for transmitting pipelined bus transactions on the bus with a current pipeline depth varying up to a current maximum pipeline depth, and for unilaterally and dynamically changing the current maximum pipeline depth.

3. A system comprising:

a plurality of agents; and

a bus controller, within each of the plurality of agents connected to a bus, to transmit pipelined bus transactions on the bus with a current pipeline depth varying up to a current maximum pipeline depth and to unilaterally and dynamically change the current maximum pipeline depth.