Move rdma control channel traffic to its own endpoint #321
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rebased against the master branch and resolved conflicts from the id pool changes. |
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Fixed an |
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| /* look for control messages and then retry the message search | ||
| to avoid unnecessary polling / queueing. */ | ||
| if (OFI_UNLIKELY(!polled_cq && !have_ctrl)) { | ||
| ofi_process_cq_rail(ep, &ep->control_rail); |
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| @@ -4659,6 +4661,14 @@ static int send(nccl_net_ofi_send_comm_t *send_comm, void *data, int size, int t | |||
| goto error; | |||
| } | |||
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| /* look for control messages and then retry the message search | |||
| to avoid unnecessary polling / queueing. */ | |||
| if (OFI_UNLIKELY(!polled_cq && !have_ctrl)) { | |||
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Because it's going to take forever, so optimize for the fast path.
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Converting this PR to a draft. #344 includes all but the last two patches, which actually create the control QP/CQ. Those two patches impact performance in a way that needs more work. Leaving this PR so that we don't lose the work, but in the mean time, we'll get the refactoring code in as part of #344. |
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Please merge master. |
Signed-off-by: Brian Barrett <[email protected]>
For the long message RDMA protocol, we want to make sure that we never starve the sender for data to move, which means prioritizing control messages from the receiver to the sender. This patch moves both the communicator setup and recv control messages to a new endpoint, which is always on device rail 0. Future patches will optimize polling of the control message cq in the send path and setting priority bits on the control cq. Signed-off-by: Brian Barrett <[email protected]>
If a match isn't found for the current send, poll the control cq to see if the match can be found. While this extends the current send() call, it potentially lowers the time until data transfer starts. Signed-off-by: Brian Barrett <[email protected]>
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This is now so hopelessly out of date that I'm going to close the PR. @rajachan is working on refactoring to work with HEAD of master. |
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This is a series of cleanup patches that includes splitting some of the initialization of Libfabric between the send/recv and rdma transports, with the end goal of making it easier to move the control channel data from the data endpoint to its own endpoint (always on "NIC 0"), so that we can eventually increase the priority level of control messages over data messages (when Libfabric/rdma-core supports the service level feature through to the card).
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.