Performing an allreduce operation using shared memory

1. A method for performing an allreduce operation using shared memory, the method comprising:

receiving, by at least one of a plurality of processing cores on a compute node, an instruction to perform an allreduce operation, wherein the plurality of processing cores share the shared memory;

establishing, by the core that received the instruction, a job status object that specifies a plurality of shared memory allreduce work units, the plurality of shared memory allreduce work units together perform the allreduce operation on the compute node, wherein the job status object is a data structure in shared memory that indicates, for each of the plurality of shared memory allreduce work units, at least one data element to be processed and a type of processing to be performed on the at least one data element;

determining, by an available core of the plurality of processing cores on the compute node, a next shared memory allreduce work unit in the job status object to be processed; and

performing, by that available core on the compute node, that next shared memory allreduce work unit.

2. The method of claim 1 wherein establishing, by the core that received the instruction, a job status object for specifying a plurality of shared memory allreduce work units further comprises assigning a plurality of threads for executing the shared memory allreduce work units.

3. The method of claim 1 further comprising:

copying, by each available core on the compute node into separate shared memory buffers, an array to be reduced by the allreduce operation; and

updating, by each available core on the compute node, the job status object with a descriptor of the shared memory buffer into which the available core copied the array.

4. The method of claim 1 further comprising:

providing, by each available core to each other available core, a read-only window into a local memory buffer containing an array to be reduced by the allreduce operation; and

updating, by each available core on the compute node, the job status object with a descriptor of the buffer into which the read-only window is provided.

5. The method of claim 1 wherein performing, by that available core on the compute node, that next shared memory allreduce work unit further comprises performing a reduction operation on elements of arrays to be reduced.

6. The method of claim 1 wherein:

the compute node is connected to a plurality of other compute nodes through a data communications network; and

performing, by that available core on the compute node, that next shared memory allreduce work unit further comprises transmitting, by that available core, local reduction results to one or more of the other compute nodes through the network.

7. The method of claim 1 wherein:

the compute node is connected to a plurality of other compute nodes through a data communications network;

performing, by that available core on the compute node, that next shared memory allreduce work unit further comprises:

receiving global reduction results through the network, and

storing the global reduction results into shared memory; and

the method further comprises copying, by each available core on the compute node, the global reduction results from the shared memory to local memory of the available core.

8. A compute node for performing an allreduce operation using shared memory, the compute node comprising a plurality of processing cores, computer memory operatively coupled to the plurality of processing cores, the computer memory having disposed within it computer program instructions capable of:

receiving, by at least one of a plurality of processing cores on a compute node, an instruction to perform an allreduce operation, wherein the plurality of processing cores share the shared memory;

establishing, by the core that received the instruction, a job status object that specifies a plurality of shared memory allreduce work units, the plurality of shared memory allreduce work units together perform the allreduce operation on the compute node, wherein the job status object is a data structure in shared memory that indicates, for each of the plurality of shared memory allreduce work units, at least one data element to be processed and a type of processing to be performed on the at least one data element;

determining, by an available core of the plurality of processing cores on the compute node, a next shared memory allreduce work unit in the job status object to be processed; and

performing, by that available core on the compute node, that next shared memory allreduce work unit.

9. The compute node of claim 8 wherein the computer memory also has disposed within it computer program instructions capable of:

copying, by each available core on the compute node into separate shared memory buffers, an array to be reduced by the allreduce operation; and

updating, by each available core on the compute node, the job status object with a descriptor of the shared memory buffer into which the available core copied the array.

10. The compute node of claim 8 wherein the computer memory also has disposed within it computer program instructions capable of:

providing, by each available core to each other available core, a read-only window into a local memory buffer containing an array to be reduced by the allreduce operation; and

updating, by each available core on the compute node, the job status object with a descriptor of the buffer into which the read-only window is provided.

11. The compute node of claim 8 wherein performing, by that available core on the compute node, that next shared memory allreduce work unit further comprises performing a reduction operation on elements of arrays to be reduced.

12. The compute node of claim 8 wherein:

the compute node is connected to a plurality of other compute nodes through a data communications network; and

performing, by that available core on the compute node, that next shared memory allreduce work unit further comprises transmitting, by that available core, local reduction results to one or more of the other compute nodes through the network.

13. The compute node of claim 8 wherein:

the compute node is connected to a plurality of other compute nodes through a data communications network;

performing, by that available core on the compute node, that next shared memory allreduce work unit further comprises:

receiving global reduction results through the network, and

storing the global reduction results into shared memory; and

the computer memory also has disposed within it computer program instructions capable of copying, by each available core on the compute node, the global reduction results from the shared memory to local memory of the available core.

14. A computer program product for performing an allreduce operation using shared memory, the computer program product disposed upon a computer-readable medium that is not a signal, the computer program product comprising computer program instructions capable of:

receiving, by at least one of a plurality of processing cores on a compute node, an instruction to perform an allreduce operation, wherein the plurality of processing cores share the shared memory;

establishing, by the core that received the instruction, a job status object that specifies a plurality of shared memory allreduce work units, the plurality of shared memory allreduce work units together perform the allreduce operation on the compute node, wherein the job status object is a data structure in shared memory that indicates, for each of the plurality of shared memory allreduce work units, at least one data element to be processed and a type of processing to be performed on the at least one data element;

determining, by an available core of the plurality of processing cores on the compute node, a next shared memory allreduce work unit in the job status object to be processed; and

performing, by that available core on the compute node, that next shared memory allreduce work unit.

15. The computer program product of claim 14 wherein establishing, by the core that received the instruction, a job status object for specifying a plurality of shared memory allreduce work units further comprises assigning a plurality of threads for executing the shared memory allreduce work units.

16. The computer program product of claim 14 further comprising computer program instructions capable of:

copying, by each available core on the compute node into separate shared memory buffers, an array to be reduced by the allreduce operation; and

updating, by each available core on the compute node, the job status object with a descriptor of the shared memory buffer into which the available core copied the array.

17. The computer program product of claim 14 further comprising computer program instructions capable of:

providing, by each available core to each other available core, a read-only window into a local memory buffer containing an array to be reduced by the allreduce operation; and

updating, by each available core on the compute node, the job status object with a descriptor of the buffer into which the read-only window is provided.

18. The computer program product of claim 14 wherein performing, by that available core on the compute node, that next shared memory allreduce work unit further comprises performing a reduction operation on elements of arrays to be reduced.

19. The computer program product of claim 14 wherein:

the compute node is connected to a plurality of other compute nodes through a data communications network; and

performing, by that available core on the compute node, that next shared memory allreduce work unit further comprises transmitting, by that available core, local reduction results to one or more of the other compute nodes through the network.

20. The computer program product of claim 14 wherein:

the compute node is connected to a plurality of other compute nodes through a data communications network;

performing, by that available core on the compute node, that next shared memory allreduce work unit further comprises:

receiving global reduction results through the network, and

storing the global reduction results into shared memory; and

the computer program product further comprises computer program instructions capable of copying, by each available core on the compute node, the global reduction results from the shared memory to local memory of the available core.