109 lines
3.0 KiB
Markdown
109 lines
3.0 KiB
Markdown
# perfi.sh
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A script that uses gnuplot to plot `iperf3` output in realtime.
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## iperf3
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```bash
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iperf3 -i $PINTERVAL -R -t $PTIME -f k -c $PERFHOST
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```
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`-i` is the interval in Seconds. Can be a float like `0.1`
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`-f` is the ouptut and allows
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- `-k` Kbit/s
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- `-m` Mbit/s
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- `-K` Kbyte/s
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- `-M` MByte/s
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There exists a [list of public iperf servers](https://iperf.fr/iperf-servers.php) but though it seemed quite recent as of today, none of the servers I tried did actually work.
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## stdbuf
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`iperf3` seems to buffer its `stdout`. A tool named `stdbuf` helps achieving realtime output, so the data can be piped into the next tool.
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```bash
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stdbuf -o0 iperf3 -i $PINTERVAL -R -t $PTIME -f k -c $PERFHOST
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```
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`-o` refers to the `STDOUT` (there is also `-i` for `STDIN` and `-e` for `STDERR`). `0` will turn buffering off. `L` would enable Line Buffering.
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## awk
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`awk` is used to only get the data rate (7th column)
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iperf3 example output:
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```bash
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iperf3 -c 192.168.2.70 -f k -t 2
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Connecting to host 192.168.2.70, port 5201
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[ 5] local 192.168.2.199 port 59798 connected to 192.168.2.70 port 5201
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[ ID] Interval Transfer Bitrate Retr Cwnd
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[ 5] 0.00-1.00 sec 28.3 MBytes 237649 Kbits/sec 0 1.21 MBytes
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[ 5] 1.00-2.00 sec 31.2 MBytes 261938 Kbits/sec 0 2.16 MBytes
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- - - - - - - - - - - - - - - - - - - - - - - - -
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[ ID] Interval Transfer Bitrate Retr
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[ 5] 0.00-2.00 sec 59.6 MBytes 249797 Kbits/sec 0 sender
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[ 5] 0.00-2.02 sec 57.2 MBytes 237330 Kbits/sec receiver
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iperf Done.
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```
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```bash
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awk '/sec/&&!/receiver/&&!/sender/ {print $7}'
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```
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The `/sec/` will filter all lines that show a data rate. To filter out the summary at the end, we add `&&!/receiver/&&!/sender/`. `&&` is logical `AND` and `!` negates the token.
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So this would result in
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```
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iperf3 -c 192.168.2.70 -f k -t 2 | awk '/sec/&&!/receiver/&&!/sender/ {print $7}'
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281725
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262140
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```
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## feedgnuplot
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`feedgnuplot` is a wrapper that makes it simpler to feed data to `gnuplot` in real time.
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```bash
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feedgnuplot --lines --stream --ylabel 'KBytes/sec' --xlabel 'seconds'
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```
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`--lines` tells (feed)gnuplot to connect datapoints by lines (which is easier to read then only points/dots
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`--stream` tells (feed)gnuplot to update its data as it comes in. Per default it will do this once per second.
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`--ylabel / --xlabel` will write a caption. It is not mandatory, but if you want to share the plot later it looks nicer.
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## Full commandline
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(See [perfi.sh](perfi.sh))
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```bash
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stdbuf -o0 iperf3 -i $PINTERVAL -R -t $PTIME -f k -c $PERFHOST | stdbuf -o0 awk '/sec/&&!/receiver/&&!/sender/ {print $7}' | stdbuf -o0 feedgnuplot --lines --stream $PINTERVAL --ylabel 'Kbit/s' --xlabel "$PINTERVAL seconds"
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```
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## Result
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## Room for improvement
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- Let user have a commandline switch for the unit (kbit/s vs. mbit/s etc.)
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- Add checks for dependencies and commandline switches
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