US 9,178,832 B2Granted

Queue credit management

AssigneeInternational Business Machines Corporation

InventorsPrakash B. Baratam, Brian T. Vanderpool

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Abstract

To prevent buffer overflow, a receiving entity may use credits to control the total amount of packets any single transmitting entity can forward. Once the assigned credits are spent, the transmitting entity cannot send data portions to the receiving entity until additional credits are provided. However, the logic in the receiving entity may be designed to manage a maximum number of credits that is less than the capacity of the buffer in the transmitting entity. For example, the receiving entity is designed to manage a maximum of eight credits but the buffer has room for twelve data portions. To use the buffer efficiently, the transmitting entity may identify when extra buffer storage is available and provide additional credits. In addition, the transmitting entity may control when the credits are provided such that the receiving entity is not allocated more credits that it was designed to manage.

Claims11

Dependent claims

A computer program product comprising:

a computer-readable storage device having computer-readable program code embodied therewith, the computer-readable program code comprising computer-readable program code configured to:
provide a number of credits to a first module not in excess of a maximum number of credits the first module is designed to manage, wherein the first module maintains a credit count that is decreased each time a data packet is transmitted from the first module to a second module;
store a plurality of received data packets from the first module in a memory buffer in the second module, the memory buffer having predefined memory locations dedicated to storing data packets received only from the first module, wherein the number of memory locations exceeds the maximum number of credits the first module is designed to manage;
determine a total number of extra credits allowed to the first module by subtracting the maximum number of credits from the number of memory locations;
and
upon determining that the credit count of the first module is less than the maximum number of credits and that there is available space in the memory locations, provide an extra credit to the first module from the total number of extra credits to thereby increase the credit count without exceeding the maximum number of credits that the first module is designed to manage.

3 more elements

A system, comprising:

a first module designed to manage no more than a maximum number of credits, the first module is configured to maintain a credit count that decreases each time a data packet is transmitted by the first module;
a second module comprising a memory buffer;
and
an interconnect coupling the first module to the memory buffer in the second module,
wherein the second module is configured to:
provide the maximum number of credits to the first module;
store a plurality of data packets received from the first module in the memory buffer, the memory buffer having predefined memory locations dedicated to storing data packets received only from the first module, wherein the number of memory locations exceeds the maximum number of credits the first module is designed to manage;
determine a total number of extra credits allowed to the first module by subtracting the maximum number of credits from the number of memory locations;
and
upon determining that the credit count of the first module is less than the maximum number of credits and that there is available space in the memory locations, provide an extra credit to the first module from the total number of extra credits to thereby increase the credit count without exceeding the maximum number of credits that the first module is designed to manage.

7 more elements

Dependencies are inferred from the claim text.