Method and apparatus for non-sequential resource access

A method for accessing shared resources in a multiprocessor system having a plurality of processors coupled to a plurality of hardware shared resources, the method comprising the steps of:

• generating in unique hardware for each processor a plurality of resource requests from that processor, each of the resource requests comprising:
• an address for a requested shared resource;
• and
• a request tag designating a memory element physically located within the processor where the resource request is to be returned;
• presenting all of the resource requests to a switching mechanism separate from and physically connected to all of the processors and to the hardware shared resources in a time order in which the resource requests were issued;
• storing the request tags associated with the resource requests in a tag queue in the switching mechanism;
• sending the resource requests to the requested one of a plurality of hardware shared resources that will service the resource requests as the requested shared resources become available to produce a resource response and return the resource response to the switching mechanism in an order in which the resource requests are serviced;
• associating the respective tag from the tag queue with the resource response;
• and
• returning the resource response and respective tag to the processor,
• whereby the resource responses may be returned out-of-order as compared with the time order in which the resource requests were issued.

An apparatus for non-sequential shared resource access in a multiprocessor system having a plurality of hardware requestors coupled to at a plurality of hardware shared resources, the apparatus comprising:

• a unique request generation means physically connected to each hardware requestor for generating a plurality of resource requests from that hardware requestor, each of the resource requests comprising;
• an address for a requested shared resource;
• and
• a request tag designating a memory means physically located within the processor for storing the resource request that is to be returned;
• a separate switching means physically connected to all of the request generation means for receiving the resource requests in a time order in which the resource requests were generated and routing the resource requests to the requested hardware shared resources, the switching means including:
• tag queue means for storing the request tags associated with the resource requests;
• and
• logic means for associating the respective request tag from the tag queue means with a resource response;
• and
• means for returning the resource response and respective request tag to the hardware requestor;
• and
• a plurality of hardware shared resource means physically connected to the switching means for servicing the resource requests as the requested hardware shared resources become available and returning the resource response to the switching means in an order in which the resource requests are serviced that is not required to be the same as the time order in which the resource requests were issued.

A method for accessing shared resources in a multiprocessor system having a plurality of hardware requestors physically coupled to a plurality of hardware shared resources, the hardware requestors including both processors and external interface ports, the hardware shared resources including main memory, global registers and interrupt mechanisms, the method comprising the steps of:

• generating in unique hardware for each hardware requestor a plurality of resource requests from that hardware requestor, each of the resource requests comprising:
• an address for a requested shared resource;
• and
• a request tag designating a memory element physically located within the hardware requestor where the resource request is to be returned;
• presenting the resource requests to a switching mechanism separate from and physically connected to both the requestors and the hardware shared resources in a time order in which the resource requests were issued;
• storing the request tags associated with the resource requests in a tag queue in the switching mechanism;
• sending the resource requests to the requested one of a plurality of hardware shared resources that will serve the resource requests as the requested hardware shared resources become available to produce a resource response and return the resource response to the switching mechanism in an order in which the resource requests are serviced that may be different than the time order in which the resource requests were issued;
• associating the respective tag from the tag queue with the resource response;
• and
• returning the resource response and respective tag to the hardware requestor.