Buffered transfer of data blocks between memory and processors independent of the order of allocation of locations in the buffer

• US 7,003,628 B1
• Filed: 12/27/2002
• Issued: 02/21/2006
• Est. Priority Date: 12/27/2002
• Status: Expired due to Fees

• Current Assignee: Unisys Corporation
• Original Assignee: Unisys Corporation
• Inventors: Wiedenman, Gregory B., Ryan, Raymond G., Eckel, Nathan A..
• Primary Examiner(s): Elmore, Stephen C.
• Application Number:
  US10/330,982
• Time in Patent Office: 1,152 Days
• Field of Search: 711/118, 711/147, 711/154, 711/156, 711/170
• US Class Current: 711/118
• CPC Class Codes: G06F 12/0859 with reload from main memory

Abstract

A data transfer system uses a data buffer and individual control of each storage location within the data buffer for improved control of data block transfers. The storage locations are assigned deallocate, active, or valid assignment bands to enable transfer control of the data blocks within the system. The deallocated storage locations are returned to an allocation pool for use as a future resource, where the active and valid assignment bands remain unavailable until deallocated. Error checking and depth control prohibit consecutive allocation or deallocation assignments as well as overflow.

Claims

1. A method for controlling data block transfers, comprising:

maintaining a pool of available storage locations within a buffer;

allocating a storage location from the pool in response to a pending request for transfer of a data block, wherein allocating includes designating the allocated storage location to be in a first state that indicates that the allocated storage location is unavailable for subsequent allocation and contains invalid data;

transferring the data block into the allocated storage location, wherein transferring includes designating the allocated storage location to be in a second state that indicates that the allocated storage location is unavailable for subsequent allocation and contains valid data; and

retrieving the data block from the allocated storage location, wherein retrieving the data block is independent of an order in which other storage locations within the buffer are allocated.

2. The method according to claim 1, wherein retrieving the data block includes

returning an allocated storage location to the pool of available storage locations once a data block is retrieved from the allocated storage location and designating the returned storage location to be in a third state that indicates that the returned storage location is available for subsequent allocation and contains invalid data.

3. The method according to claim 1, wherein a first control signal is used to determine the allocated storage location used to receive the transferred data block.

4. The method according to claim 1, wherein a second control signal is used to determine the allocated storage location from which the data block is retrieved.

5. A multiprocessor system, comprising:

a plurality of multiprocessors sharing a common system bus with access to a common memory pool; and

a node controller coupled to each of the plurality of multiprocessors, wherein the node controller includes,

a plurality of buffers coupled to receive data blocks and coupled to provide the data blocks independently of a position of the data blocks within the plurality of buffers; and

a buffer tracker coupled to the plurality of buffers to control data block transfer according to assignment bands associated with the data blocks, wherein the buffer tracker includes,

an allocation controller coupled to receive an allocation request for a storage location within the plurality of buffers and coupled to provide a first assignment band to the storage location in response to the allocation request; and

a deallocation controller coupled to receive a deallocation request for the storage location within the plurality of buffers and coupled to provide a second assignment band to the storage location in response to the deallocation request.

6. The multiprocessor system according to claim 5, wherein the plurality of buffers comprises:

a first set of buffers used to facilitate data transfer from the multiprocessors to the common memory pool; and

a second set of buffers used to facilitate data transfer from the common memory pool to the multiprocessors.

7. The multiprocessor system according to claim 5, wherein the buffer tracker further comprises an allocation pool coupled to receive the first and second assignment bands to maintain a list of available storage locations.

8. The multiprocessor system according to claim 7, wherein the allocation pool removes the storage location associated with the first assignment band from the list of available storage locations in response to receiving the first assignment band.

9. The multiprocessor system according to claim 7, wherein the allocation pool adds the storage location associated with the second assignment band to the list of available storage locations in response to receiving the second assignment band.

10. The multiprocessor system according to claim 5, wherein the buffer tracker further comprises a depth counter coupled to receive the first and second assignment bands to monitor a capacity level of the plurality of buffers and coupled to provide a signal indicative of a zero capacity level of the plurality of buffers.

11. The multiprocessor system according to claim 10, wherein the depth counter decrements the capacity level in response to receiving the first assignment band.

12. The multiprocessor system according to claim 10, wherein the depth counter increments the capacity level in response to receiving the second assignment band.

13. The multiprocessor system according to claim 5, wherein the buffer tracker further comprises an error checker coupled to receive the first and second assignment bands, wherein an error signal is provided in response to a duplicate band assignment to the same storage location.

14. A method of maintaining an assignment band of a data block within a buffer to control access to the data block, the method comprising:

establishing a first assignment band for the data block in response to receiving an allocation request;

establishing a second assignment band for the data block when data is written to the data block in accordance with a first data pointer; and

establishing a third assignment band for the data block when data is read from the data block in accordance with a second data pointer.

15. The method according to claim 14, wherein the first assignment band reserves the data block for write only access.

16. The method according to claim 15, wherein the second assignment band reserves the data block for read only access.

17. The method according to claim 14, wherein the third assignment band makes the data block available for reallocation to write only access.