Memory controller for heterogeneous computer
A memory controller for heterogeneous computer processors dynamically adjusts access priorities by the different processors to maximize performance in the execution of a single parallel application program on both processor architectures. In one embodiment, the memory controller predicts sequential memory accesses by the processor having higher memory latency or fewer access requests to lockout the other processor during those sequences for improved implementation of the intended prioritization.
1. A computer for heterogeneous computing of a single parallel application comprising;
a first processor having a first architecture;
a second processor having a second architecture different from the first architecture;
an electronic memory; and
a memory controller communicating memory access requests from the first and second processor to the memory, the memory controller giving priority to memory access requests from the first processor to a portion of the memory during a predetermined lockout period after a first memory access request from the first processor to the portion of the memory following a memory access request from the first processor to a different portion of memory.
2. The computer of claim 1 wherein the first processor has at least one of greater sensitivity to memory latency than the second processor, and a lower rate of memory access requests than the second processor.
3. The computer of claim 1 further including a lockout period adjuster measuring successive memory access requests from the first processor to the portion during execution of the single parallel application and adjusting the lockout period according to that measurement.
4. A memory controller comprising:
inputs adapted to receive memory requests from a first processor having a first architecture and a second processor having a second architecture different from the first architecture;
outputs adapted to communicate memory requests received from the first and second processors to all electronic memory to obtain data requested by the memory requests; and
a memory request lockout giving priority to memory access requests from the first processor to a portion of the memory during a predetermined lockout period after a first memory access request from the first processor to the portion of the memory following a memory access request from the first processor to a different portion of memory;
wherein the first processor has at least one of greater sensitivity to memory latency than the second processor, and a lower rate of memory access requests than the second processor.
5. The computer of claim 4 further including a lockout period adjuster measuring successive memory access requests from the first processor to the portion during execution of the single parallel application and adjusting the lockout period according to that measurement.
6. The computer of claim 5 wherein the lockout period adjuster combines multiple measures of successive memory access requests to determine the lockout period to be representative of an expected number of successive memory accesses.
7. The computer of claim 1 wherein the lockout period adjuster combines multiple measures of successive memory access requests to determine the lockout period to be representative of an expected number of successive memory accesses.
8. The computer of claim 7 wherein the lockout period adjuster is at least in part a program executing on one of the first and second processors.
9. The computer of claim 1 wherein the electronic memory includes different hanks, and wherein the portion is a given bank and the lockout period adjuster independently controls a lockout period for each bank.
10. The computer of claim 1 wherein the first processor has greater sensitivity to memory latency than the second processor.
11. The computer of claim 1 wherein the first processor makes fewer memory access requests than the second processor.
12. The computer of claim 1 wherein the first processor is at least one general-purpose computer processing unit providing a first instruction set and the second processor is at least one graphic processing unit providing a second instruction set different from the first instruction set.