Programmable system for invalidating pending requests within a data processing system

• US 6,401,223 B1
• Filed: 05/21/1999
• Issued: 06/04/2002
• Est. Priority Date: 05/21/1999
• Status: Expired due to Term

• Current Assignee: Unisys Corporation
• Original Assignee: Unisys Corporation
• Inventors: DePenning, James L.
• Primary Examiner(s): Iqbal, Nadeem
• Application Number:
  US09/316,825
• Time in Patent Office: 1,110 Days
• Field of Search: 714/42, 714/43, 714/44, 714/54, 714/5, 714/8, 714/13, 714/20, 714/25, 711/112, 711/114, 711/133
• US Class Current: 714/42
• CPC Class Codes: G06F 11/0724 in a multiprocessor or a multi-core unit multiprocessors per se G06F15/80
• CPC Class Codes: G06F 11/0793 Remedial or corrective actions recovery from an exception in an instruction pipeline G06F9/3861; by retry G06F11/1402; for recovering from a failure of a protocol instance or entity H04L69/40
• CPC Class Codes: G06F 2209/5013 Request control
• CPC Class Codes: G06F 9/5011 the resources being hardware resources other than CPUs, Servers and Terminals

Abstract

A request invalidation system for invalidating pending requests within a data processing system is disclosed. According to the system of the preferred embodiment, one or more requesting units may make requests to gain access to one or more shared resources. These requests are stored in a central request storage unit and are processed according to a predetermined priority scheme. Each request includes multiple fields for storing information about the request. Within the data processing system, error indicators are provided to indicate the occurrence of a fault, and to further provide an error indication value that provides information about the nature of the fault. Ones of these error indicators are associated with a respective one of the request fields. According to the current request invalidation system, mode control logic is provided to programmably select one of the request fields as the invalidation field. If any error indicator is asserted that is associated with the selected invalidation field, the error indication value for this error indicator is compared against the invalidation field of all pending requests. In the event a predetermined relationship exists between the two compared values, the associated pending request is discarded without being presented to the requested shared resource. According to one aspect of the invention, the invalidation field is selectable by a scan-set interface that may be dynamically re-programmed during normal system operations. According to another aspect of the invention, ones of the error indicators are each associated with a respective requesting unit or a shared resource. Once an error indicator that is associated with a requesting unit or a shared resource has been asserted, no further requests for that requesting unit or shared resource will be stored within the request storage unit until a reset operation is performed. In one embodiment of the current invalidation system, the system includes logic to generate invalidation requests, which are requests to invalidate one or more pending requests based on an invalidation field and error indication value included in the request. The invalidation system further includes logic for using the invalidation field provided by an invalidation request to override the invalidation field that is programmably selected by the scan-set interface.

Claims

1. For use in a data processing system having multiple requesting units making requests to multiple receiving units wherein each of the requests includes multiple request data fields, the data processing system further including error indicators each to indicate a respective error condition occurring within the data processing system and wherein each of the error indicators is associated with an error indication value, and is further associated with a respective one of the multiple request data fields, a request invalidation system, comprising:

a storage unit to store the requests;

a programmable mode control logic to programmably select one of the multiple request data fields as an invalidation field; and

a storage unit control logic coupled to said storage unit, coupled to said programmable mode control logic, and further coupled to detect the assertion of any of the error indicators, said storage unit control logic to cause the removal of any request from said storage unit that has a value stored in said selected invalidation field having a predetermined relationship to the error indication value associated with any of the asserted error indicators that are associated with said invalidation field.

2. The request invalidation system of claim 1, wherein said storage unit comprises multiple Content Addressable Memories (CAMs).

3. The request invalidation system of claim 1, wherein one of the multiple request data fields in each of the requests is a requester identity field indicating the identity of the requesting unit making the request, wherein ones of the error indicators are requester error indicators indicating a failure in a respective one of the requesting units, and wherein said storage unit control logic includes circuits to cause the removal of all requests stored in said storage unit that were made by any requesting unit indicated as failing by any of said requester error indicators if said requester identity field is selected as said invalidation field.

4. The request invalidation system of claim 1, wherein one of the multiple request data fields in each of the requests is a destination identity field indicating the identity the receiving unit that is to receive the request, wherein ones of the error indicators are receiving unit error indicators indicating a failure in a respective one of the receiving units, and wherein said storage unit control logic includes circuits to cause the removal of all requests stored in said storage unit that are made to any receiving unit indicated as failing by any of said receiving error indicators if said destination identity field is selected as said invalidation field.

5. The request invalidation system of claim 1, wherein one of the multiple request data fields in each of the requests is a job number field that stores data signals uniquely identifying a specific request, wherein ones of the error indicators are job number indicators identifying a request, and wherein said storage unit control logic includes circuits to cause the removal of any request stored in said storage unit for which said job number field stores data signals identifying a request identified by said job number indicators if said job number field is selected as said invalidation field.

6. The request invalidation system of claim 1, wherein the data processing system includes a scan interface, and wherein said programmable mode control logic includes a mode selection storage device that is programmable by the scan interface to store said invalidation field.

7. The request invalidation system of claim 6, and further including:

invalidation request generation logic for generating invalidation requests, wherein each of said invalidation requests is one of the error indicators, and wherein each of said invalidation requests selectably indicates one of the multiple request data fields as an invalidation-request selected field; and

wherein said programmable mode control logic includes selection circuits coupled to receive said invalidation-request selected field from said invalidation request generation logic, and to select said invalidation-request selected field as said invalidation field instead of said invalidation field stored by said mode selection storage device.

8. The request invalidation system of claim 7, wherein said invalidation request generation logic includes timer circuits for generating invalidation requests for those requests that have been pending for greater than a predetermined period of time.

9. The request invalidation system of claim 6, wherein said programmable mode control logic is further coupled to receive the error indicators, and wherein said programmable mode control logic further includes circuits to automatically override said invalidation field stored by said mode selection storage device based on the reception of error indicators not associated with said invalidation field stored by said mode selection storage device.

10. A storage device having multiple addressable locations each for storing data entries, wherein each of the data entries includes multiple fields, the memory further for receiving input compare signals to be compared against a selectable one of the multiple fields, the storage device comprising:

multiple Content Addressable Memories, each having multiple addressable locations to store a respective one of the multiple fields for each of the data entries, wherein each of said CAMs is capable of generating a respective group of CAM compare signals to indicate whether the input compare signals has a predetermined relationship to the signals stored in any of the multiple address locations;

a CAM compare selection circuit coupled to each of said multiple CAMs to receive each of said groups of CAM compare signals; and

a programmable mode selection circuit coupled to said CAM compare selection circuit to cause said CAM compare selection circuit to select one of said groups of CAM compare signals from a selected one of said multiple CAMs that stores a selected one of the multiple fields based on programmable mode selection signals provided by said programmable mode selection circuit.

11. The storage device of claim 10, and further including a scan-set interface coupled to said programmable mode selection circuit to program said programmable mode selection circuit with said programmable mode selection signals.

12. The storage device of claim 10, and further including a Random Access Memory device coupled to each of said CAMs to implement selected ones of the multiple fields.

13. The storage device of claim 10, and further including control logic coupled to receive from said CAM compare selection circuit said selected one of said groups of CAM compare signals as invalidation signals, and to utilize said invalidation signals to discard ones of the data entries having signals stored in said selected one of the multiple fields that have a predetermined relationship to the input compare signals.

14. The storage device of claim 13, wherein the storage device is for use in a data processing system having one or more requesting units and one or more receiving units, wherein the memory is to store as each of the entries a respective request, each of the requests provided by one of the requesting units requesting access to a receiving unit and each request including each of the multiple fields, the data processing system further including error indicators indicative of an error associated with a respective one of the multiple fields, and further comprising an input selection circuit coupled to said programmable mode selection circuit to select one of said error indicators as the input compare signals.

15. The storage device of claim 14, wherein the data processing system further includes circuits to generate invalidation requests, each of said invalidation requests including ones of the multiple fields, wherein said invalidation request includes field select signals, and further including an invalidation request selection circuit coupled to said input selection circuit to receive each of said invalidation requests, and to select one of the multiple fields in each of said invalidation requests as the input compare signals based on said field select signals in said each of said invalidation requests.

16. The storage device of claim 15, wherein said programmable mode selection circuit includes a selection circuit to receive said field select signals from each said invalidation request, and to select said field select signals as said programmable mode selection signals.

17. The storage device of claim 14, wherein said programmable mode selection circuit includes a priority logic circuit coupled to receive the error indicators, said programmable mode selection circuit to generate said programmable mode selection signals upon the assertion of any of the error indicators, wherein said programmable mode selection signals selects said respective one of the multiple fields associated with said error indicated by said asserted error indicator.

18. For use in a data processing system having multiple requesting units requesting access to multiple receiving units, a request invalidation system, comprising:

storage means for storing requests provided by a respective one of the multiple requesting units for gaining access to one of the multiple receiving units, wherein each of said requests includes multiple data fields;

error storage means for receiving error indicators each indicative of a fault occurring within the data processing system and each being associated with a respective one of said data fields;

mode selection means for programmably selecting one of said data fields for use as an invalidation field; and

storage address means for removing from said storage means any of said stored requests for which said invalidation field has a predetermined relationship to any of said error indicators that is associated with said one of said data fields selected as said invalidation field.

19. The request invalidation system of claim 18, wherein the mode selection means includes means for detecting the assertion of any of said error indicators and for selecting as said invalidation field the data field that is associated with a selected one of said asserted error indicators.

20. The request invalidation system of claim 18, wherein ones of said error indicators are each associated with a respective one of the requesting units, and other ones of said error indicators are each associated with a respective one of the receiving units, and further including request blocking means for preventing requests received from a requesting unit associated with a previously-received error indicator, or requests to a receiving unit associated with a previously-received error indicator are blocked from being stored in said storage means.