Bus arbitration method

Abstract

The present invention provides a bus arbitration method. Said bus arbitration method is used in bus tiebreaker. Said bus arbitration method has first priority and second priority, in which the second priority is higher than first priority. Said method includes the following steps: giving a life period to request of first priority; backwards timing said lift period; when the described life period is completed, promoting the priority with the described request to be second priority; in which the described life period can be transferred with said request.

Description

technical field [0001] The invention relates to a bus arbitration method. Background technique [0002] The computer system includes a master unit (MASTER) and a slave unit (SLAVE), and the data exchange between the master unit and the slave unit is completed through the bus (BUS). When a master unit wants to access a slave unit, it first sends a request to the bus, and the bus arbiter arbitrates the received request, selects the request with the highest priority order, and the master unit corresponding to the request with the highest priority order can The control bus accesses the corresponding slave units. Each main unit has certain requirements on bus bandwidth (Bandwidth) and delay (Latency). For example, the central processing unit (CPU) has higher requirements on delay, while the video processing module has higher requirements on bandwidth. Generally speaking, the request sent by the master unit with high delay requirement will be given high priority, while the maste...

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Problems solved by technology

[0004] However, the above scheme still has the following shortcomings: first, the difficulty of chip wiring is high; second, the degree of componentization is not high; third, the control of the response time is not precise enough, as detailed below

If the priority of the request is raised through the lower-level arbiter, it may happen that the request gets the response of the arbiter more smoothly (the priority is not raised) but is blocked in the higher-level arbiter, and there is no guarantee that it will Obtain a response from the top-level arbiter within the specified delay; if the priority of the request is raised through the higher-level arbiter, it may occur that the request has been blocked in the lower-level arbiter for more than the specified maximum delay, and cannot Guaranteed to get a response from the top-level arbitrator within the specified delay, the existing technology obviously cannot accurately control the response time of the request

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