Total connections handled¶

Total number of connections handled by the SMC module. Includes TCP fallback connections as well as handshake errors.

SMC connections¶

Number of connections that successfully entered the respective SMC mode. -d/--details breaks up connections by SMC versions.

Handshake errors¶

Number of connections that failed due to errors during the handshaking phase, e.g. peer no longer responding.

Avg requests per SMC conn¶

Average number of requests sent and received (including special socket calls) per SMC connection.

TCP fallback¶

Number of connections that fell back to TCP/IP.

Data transmitted¶

Amount of data sent (TX) or received (RX) in Bytes.

Total requests¶

Total number of individual send (TX) or receive (RX) requests handled. Includes requests that ended with errors or did not transfer any data.

Buffer full¶

Number of occurrences where the respective send buffer (TX) could not contain all data to be sent, or did not contain as much data as requested in a receive call (RX).

Buffer full (remote) (--details only)¶

Number of occurrences where the peer's receive buffer was exceeded by writing data. That is, requests that fill the buffer up to the last bit are not included in the count.

Buffer too small (--details only)¶

Number of occurrences where a send request was larger than the local send buffer's total capacity.

Buffer too small (remote) (--details only)¶

Number of occurrences where a send request exceeded the total capacity of the peer's receive buffer.

Buffer downgrades (--details only)¶

Number of occurrences where a buffer of the requested size could not be allocated for a new connection, and a smaller buffer was used.

Buffer reuses (--details only)¶

Number of occurrences where a buffer was provided as requested for a new connection by reusing a buffer from a previous connection.

Bufs¶

Histogram of buffer sizes for all connections, including buffer downgrades and buffer reuses. The histogram scale presents exact buffer sizes.

Reqs¶

Histogram of request sizes. The histogram scale includes upper boundaries of request sizes. Counts reflect requested send sizes for TX, and actual receive sizes for RX. Difference to Total requests is due to requests not transferring any data and/or erroneous requests.

Special socket calls¶

Summarizes the total number of sockets calls that require special handling in SMC. To categorize these calls into individual counters as follows, use the -d/--details option.

cork

Counts occurrences of sockopt TCP_CORK enablements. That is, does not reflect the number of send requests with TCP_CORK enabled.

nodelay

Counts occurrences of sockopt TCP_NODELAY enablements. That is, does not reflect the number of send requests with TCP_CORK enabled.

sendpage

Counts occurrences of the AF_SMC implementation of the sendpage call.

splice

Counts number of calls of the splice() system call.

urgent data

Counts number of send and receive calls with MSG_OOB set.