System and method for direct memory access buffer utilization by setting DMA controller with plurality of arbitration weights associated with different DMA engines
A DMA controller allocates space at a buffer to different DMA engines based on the length of time data segments have been stored at a buffer. This allocation ensures that DMA engines associated with a destination that is experiencing higher congestion will be assigned less buffer space than a destination that is experiencing lower congestion. Further, the DMA controller is able to adapt to changing congestion conditions at the transfer destinations.
1. A method, comprising:
assigning space at a buffer of a direct memory access (DMA) controller to a first DMA engine based on the amount of time a first data segment has been stored at the buffer, the first data segment to be transferred by the first DMA engine, the buffer to store data segments for a plurality of DMA engines including the first DMA engine.
2. The method of claim 1 , further comprising:
assigning space at the buffer to a second DMA engine of the plurality of DMA engines based on the amount of time a second data segment associated with the second DMA engine has been stored at the buffer.
3. The method of claim 2 wherein assigning space at the buffer to the first DMA engine comprises assigning space at the buffer based on the relative amount of time the first and second data segments have been stored at the buffer.
4. The method of claim 1 , further comprises assigning the space at the buffer to a second DMA engine instead of the first DMA engine in response to determining the first data segment has been stored at the buffer for greater than a threshold amount of time.
5. The method of claim 1 , wherein assigning space at the buffer comprises:
determining the amount of time the first data segment has been stored based on the difference between a first counter value corresponding to a time when the space at the buffer becomes available and a second counter value corresponding to when the first data segment was stored at the buffer.
6. The method of claim 5 , further comprising:
setting an indicator in response to determining a wrap of the counter with respect to the second counter value; and
assigning the space at the buffer to any of a plurality of DMA engines instead of the first DMA engine while the indicator is set.
7. The method of claim 1 , wherein assigning the space at the buffer comprises assigning the space at the buffer in response to determining a dedicated portion of the buffer associated with the first DMA engine is not available to store a second data segment.
8. A method, comprising:
setting by a DMA controller each of a plurality of arbitration weights based on the corresponding amount of time that each of a plurality of data segments have been stored at a buffer of a direct memory access (DMA) controller, each of the plurality of weights associated with a different corresponding one of a plurality of DMA engines; and
assigning one or more spaces at the buffer to each of the plurality of DMA engines of the DMA controller based on the plurality of arbitration weights.
9. The method of claim 8 , wherein setting the plurality of arbitration weights comprises:
setting by the DMA controller a first weight for a first DMA engine of the plurality of DMA engines based on the amount of time a first data segment of the plurality of data segments has been stored at the buffer; and
setting by the DMA controller a second weight for a second DMA engine of the plurality of DMA engines to be lower than the first weight in response to determining that a second segment of the plurality of data segments has been stored at the buffer for more time than the first data segment, the second data segment associated with the second DMA engine.
10. The method of claim 9 , wherein setting the plurality of arbitration weights comprises:
setting the first weight to a defined value in response to determining the first data segment has been stored at the buffer for a threshold amount of time.
11. The method of claim 10 , wherein determining the first segment has been stored at the buffer for the threshold amount of time comprises determining that a counter value has wrapped since the first data segment was stored at the buffer.
12. The method of claim 9 , wherein setting the first weight further comprises setting the first weight based on the amount of time the first data segment has been stored at the buffer in response to determining a dedicated buffer slot associated with the first DMA engine is not available to store a second data segment.
13. The method of claim 12 , wherein setting the plurality of arbitration weights further comprises setting the first weight to a defined value in response to determining that the dedicated buffer slot is available to store the second data segment.
14. A direct memory access (DMA) controller, comprising:
a plurality of DMA engines to execute data transfers;
a buffer comprising a plurality of buffer slots including a first buffer slot and a second buffer slot, the buffer to store data segments for the plurality of DMA engines; and
a control module to assign a buffer slot to one of the plurality of DMA engines based on an amount of time a plurality of data segments associated with the plurality of DMA engines have been stored at the buffer.
15. The DMA controller of claim 14 , further comprising:
an arbiter to determine a set of weights based on the amount of time the plurality of data segments have been stored at the second buffer slot; and
wherein the control module is to assign the first buffer slot based on the set of weights.
16. The DMA controller of claim 15 , wherein the arbiter is to set one of the plurality of weights to a defined value in response to determining one of the plurality of data segments has been stored at the buffer for a threshold amount of time.
17. The DMA controller of claim 16 , further comprising a counter and wherein the arbiter is to determine that the one of the plurality of data segments has been stored at the buffer for the threshold amount of time in response to determining that a value at the counter wrapped since the one of the plurality of data segments was stored at the buffer.
18. The DMA controller of claim 15 , wherein the arbiter is to set one of the plurality of weights to a defined value in response to determining that a buffer slot dedicated to the one of the plurality of DMA engines is available to store data.
19. The DMA controller of claim 14 , wherein the control module assigns buffer slots based on the amount of time the oldest data segment associated with each of the plurality of DMA engines has been stored at the buffer.
20. The DMA controller of claim 14 , further comprising a counter coupled to the control module, the control module to determine amount of time the plurality of data segments associated with the plurality of DMA engines have been stored at the buffer based on the counter.