System and method for facilitating efficient packet forwarding in a network interface controller (NIC)
A network interface controller (NIC) capable of efficient packet forwarding is provided. The NIC can be equipped with a host interface, a packet generation logic block, and a forwarding logic block. During operation, the packet generation logic block can obtain, via the host interface, a message from the host device and for a remote device. The packet generation logic block may generate a plurality of packets for the remote device from the message. The forwarding logic block can then send a first subset of packets of the plurality of packets based on ordered delivery. If a first condition is met, the forwarding logic block can send a second subset of packets of the plurality of packets based on unordered delivery. Furthermore, if a second condition is met, the forwarding logic block can send a third subset of packets of the plurality of packets based on ordered delivery.
1. A network interface controller (NIC), comprising:
one or more processors; and
memory including computer code that when executed, causes the one or more processors to send packets of a message according to a prescribed ordered-delivery-at-message-boundary policy that utilizes both ordered delivery and unordered delivery of the message to improve performance while preserving order at boundaries of the message, the prescribed ordered-delivery-at-message-boundary policy comprising instructions to:
send an initial subset of the packets associated with an initial portion of the message based on ordered delivery;
in response to a first condition associated with the ordered delivery, send a middle subset of the packets associated with a middle portion of the message based on unordered delivery;
refrain from sending a last subset of the packets until the NIC has received responses for the unordered delivery; and
in response to a second condition associated with unordered delivery, send the last subset of the packets associated with a last portion of the message based on the ordered delivery.
2. The network interface controller of claim 1 , wherein triggering the first condition comprises receiving, from a remote device that is an intended recipient of the message, a response for one of the initial subset of the packets.
3. The network interface controller of claim 1 , wherein triggering the second condition comprises determining that a number of packets in the last subset of the packets is less than a second threshold.
4. The network interface controller of claim 3 , wherein the second threshold indicates a number of outstanding packets in the initial subset of the packets and middle subset of the packets.
5. The network interface controller of claim 1 , wherein the computer code when executed further causes the one or more processors to:
identify a final packet in the last subset of the packets; and
refrain from sending the final packet until receiving respective responses for all packets in the middle subset of the packets.
6. The network interface controller of claim 1 , wherein the initial, middle, and last subsets of the packets are sent in a non-overlapping sequence.
7. The network interface controller of claim 1 , wherein the computer code when executed further causes the one or more processors to:
maintain a first counter indicating a number of outstanding packets in the initial subset of the packets and last subset of the packets; and
maintain a second counter indicating a number of outstanding packets in the middle subset of the packets.
8. The network interface controller of claim 1 , wherein the computer code when executed further causes the one or more processors to set a flag in a respective packet in the initial subset of the packets and last subset of the packets, wherein the flag indicates that an ordered delivery of the packets is required.
9. The network interface controller of claim 1 , wherein the message corresponds to a remote direct memory access (RDMA) command.
10. The NIC of claim 1 , wherein the boundaries of the message correspond with a size of the message or a number of the packets of a packet stream.
11. The NIC of claim 1 , wherein the initial subset of the packets, the middle subset of the packets, and the last subset of the packets each correspond with indicators indicating that in-order delivery is strictly enforced.
12. The NIC of claim 1 , wherein the initial subset of the packets correspond with a first set of sequence numbers that are less than a second set of sequence numbers corresponding to the middle subset of the packets and the last subset of the packets.
13. A method, comprising:
obtaining, via a host interface, a message from a host device and for a remote device; and
sending packets of the message according to a prescribed ordered-delivery-at-message-boundary policy that utilizes both ordered delivery and unordered delivery of the message to improve performance while preserving order at boundaries of the message, the prescribed ordered-delivery-at-message-boundary policy comprising:
sending an initial subset of the packets associated with an initial portion of the message based on ordered delivery,
in response to a first condition associated with the ordered delivery, sending a middle subset of the packets associated with a middle portion of the message based on unordered delivery,
refrain from sending a last subset of the packets until responses are received for the unordered delivery, and
in response to a second condition associated with unordered delivery, sending the last subset of the packets associated with a last portion of a message based on the ordered delivery.
14. The method of claim 13 , wherein triggering the first condition comprises receiving, from the remote device, a response for one of the initial subset of the packets.
15. The method of claim 13 , wherein triggering the second condition comprises determining that a number of packets in the last subset of the packets is less than a second threshold.
16. The method of claim 15 , wherein the second threshold indicates a number of outstanding packets in the initial subset of the packets and middle subset of the packets.
17. The method of claim 13 , further comprising:
identifying a final packet in the last subset of the packets; and
refraining from sending the final packet until receiving respective responses for all packets in the middle subset of the packets.
18. The method of claim 13 , further comprising:
maintaining a first counter indicating a number of outstanding packets in the initial subset of the packets and last subset of the packets; and
maintaining a second counter indicating a number of outstanding packets in the middle subset of the packets.
19. The method of claim 13 , further comprising setting a flag in a respective packet in the initial subset of the packets and last subset of the packets, wherein the flag indicates that an ordered delivery of the packets is required.
20. The method of claim 13 , wherein the message corresponds to a remote direct memory access (RDMA) command.