25 lines
940 B
Plaintext
25 lines
940 B
Plaintext
Demonstrations of tcpsynbl, the Linux bpftrace/eBPF version.
|
|
|
|
|
|
This tool shows the TCP SYN backlog size during SYN arrival as a histogram.
|
|
This lets you see how close your applications are to hitting the backlog limit
|
|
and dropping SYNs (causing performance issues with SYN retransmits). For
|
|
example:
|
|
|
|
# ./tcpsynbl.bt
|
|
Attaching 4 probes...
|
|
Tracing SYN backlog size. Ctrl-C to end.
|
|
^C
|
|
@backlog[backlog limit]: histogram of backlog size
|
|
|
|
|
|
@backlog[500]:
|
|
[0] 2266 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
|
|
[1] 3 | |
|
|
[2, 4) 1 | |
|
|
|
|
This output shows that for the backlog limit of 500, there were 2266 SYN
|
|
arrivals where the backlog was zero, three where the backlog was one, and
|
|
one where the backlog was either two or three. This indicates that we are
|
|
nowhere near this limit.
|