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smcd-stats.8
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.TH SMCD-STATS 8 "June 2021" "smc-tools" "Linux Programmer's Manual"
.SH NAME
smcd-stats \- Print statistics about SMC-D usage
smcr-stats \- Print statistics about SMC-R usage
.SH "SYNOPSIS"
.sp
.ad l
.in +8
.ti -8
.B smcd
.RI "[ " OPTIONS " ]"
.B stats
.RI " { " COMMAND " | "
.BR help " }"
.sp
.ti -8
.B smcr
.RI "[ " OPTIONS " ]"
.B stats
.RI " { " COMMAND " | "
.BR help " }"
.sp
.SH DESCRIPTION
The smcd stats and smcr stats commands display statistics about SMC-D and
SMC-R, respectively. Data includes number of connections, number of failed
connections, buffer information, and special calls.
Statistics are collected at various data points in the smc kernel module.
Therefore, minor inconsistencies in the data can occur and are to be
expected.
.SH COMMANDS
.TP
.BR "show " (default)
Display statistics on respective SMC mode usage. Values displayed are
cumulative since last reset, unless option
.B -a/--absolute
is specified.
.TP
.BR reset
Display current statistics and reset all counters to zero.
.TP
.BR json
Display current statistics in JSON format.
.SH OPTIONS
.TP
.B \-d, \-\-details
Display additional fields and information in the output.
.TP
.B \-a, \-\-absolute
Display values since smc module load, ignoring any resets.
.SH OUTPUT
The
.B -d/--details
option displays a number of additional fields as indicated in the following.
It also breaks up a number of counters in section
.I Connections Summary
into separate counts for client and server.
.SS "Total connections handled"
Total number of connections handled by the SMC module. Includes
.I TCP fallback
connections as well as
.IR "handshake errors" .
.SS "SMC connections"
Number of connections that successfully entered the respective SMC mode.
.B -d/--details
breaks up connections by SMC versions.
.SS Handshake errors
Number of connections that failed due to errors during the handshaking
phase, e.g. peer no longer responding.
.SS Avg requests per SMC conn
Average number of requests sent and received (including
.IR "special socket calls" )
per SMC connection.
.SS TCP fallback
Number of connections that fell back to TCP/IP.
.SS Data transmitted
Amount of data sent (TX) or received (RX) in Bytes.
.SS 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.
.SS 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).
.SS 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.
.SS Buffer too small (\-\-details only)
Number of occurrences where a send request was larger than the local send
buffer's total capacity.
.SS Buffer too small (remote) (\-\-details only)
Number of occurrences where a send request exceeded the total capacity of the
peer's receive buffer.
.SS 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.
.SS 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.
.SS Bufs
Histogram of buffer sizes for all connections, including
.I buffer downgrades
and
.IR "buffer reuses" .
The histogram scale presents exact buffer sizes.
.SS 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
.I "Total requests"
is due to requests not transferring any data and/or erroneous requests.
.SS 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
.I -d/\-\-details
option.
.TP
.I cork
Counts occurrences of sockopt TCP_CORK enablements. That is, does not reflect
the number of send requests with TCP_CORK enabled.
.TP
.I nodelay
Counts occurrences of sockopt TCP_NODELAY enablements. That is, does not
reflect the number of send requests with TCP_CORK enabled.
.TP
.I sendpage
Counts occurrences of the AF_SMC implementation of the sendpage call.
.TP
.I splice
Counts number of calls of the splice() system call.
.TP
.I urgent data
Counts number of send and receive calls with MSG_OOB set.
.SH "EXAMPLES"
.HP 2
1. Show SMC-D statistics:
.br
\fB# smcd stats\fP
.br
.HP 2
2. Show detailed SMC-R statistics:
.br
\fB# smcr -d stats show\fP
.br
.HP 2
3. Show detailed SMC-R statistics and reset SMC-R statistics counters:
.br
\fB# smcr -d stats reset\fP
.br
.HP 2
4. Show detailed SMC-D statistics since module load in JSON format:
.br
\fB# smcd -da stats json\fP
.br
.HP 2
.HP 2
5. Show SMC-R statistics since module load:
.br
\fB# smcr -a stats\fP
.br
.HP 2
.P
.SH SEE ALSO
.BR smcd (8),
.BR smcr (8)