To protect the network, the data sent will not overwhelming the network (Congestion Control, congestion control).Then if the data continues to be sent, the buffer cannot be stored, and the receiver can only discard it. The application fills up before it can be processed.

The kernel is responsible for receiving the packets and placing them in the buffer, and then the upper-layer application processes the contents of the buffer.

The process of sending data to the receiving end is similar to the process described above. To protect the receiving end, the data sent will not exceed the buffer size of the receiving end (Flow control).In order to optimize the transmission efficiency (note that the transmission efficiency here is not the transmission efficiency of a single TCP connection, but the efficiency of the overall network), it will: This happens when the application on the sending end has written the content into the system’s buffer, but the system does not send it out quickly. Most of the cases are the 2nd and 3rd cases, which are more difficult to investigate. If the buffer is full, the application will block (if using the block API) until the buffer is available before continuing to write, producer and consumer mode.īottlenecks on the sender side are generally easier to troubleshoot, and you can even see when they are blocked through the application log. The bottleneck at the sending end is generally that the buffer is not large enough, because the sending process is that the application calls syscall to put the data to be sent into the buffer, and then the system is responsible for sending it out. The middle network layer has a bottleneck.The throughput has not reached the upper limit of the network, which may be mainly affected by three aspects: Scenarios that value throughput are generally so-called long fat networks (Long Fat Networks, LFN, rfc7323 ). This article shares a way to debug throughput. The delay is better to verify, you can see it by pinging or mtr. When debugging network quality, we generally focus on two factors: latency and throughput (bandwidth).

Tcp retransmission wireshark