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accept2close-nd_example.txt
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accept2close-nd_example.txt
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Examples of accept2close-nd.stp, the Linux SystemTap version.
This shows accepted socket lifespans, by measuring the time from syscall
accept() to close() on the same file descriptor. Sessions are printed as they
occur, and a histogram summary is printed at the end. For example:
# ./accept2close-nd.stp
TIME PID COMM FD DURATION
Sat Jan 31 05:31:14 2015 29042 node 11 1 ms
Sat Jan 31 05:31:15 2015 29042 node 11 1 ms
Sat Jan 31 05:31:15 2015 29042 node 11 1 ms
Sat Jan 31 05:31:15 2015 29042 node 11 1 ms
Sat Jan 31 05:31:15 2015 29042 node 11 1 ms
Sat Jan 31 05:31:15 2015 29042 node 11 1 ms
Sat Jan 31 05:31:15 2015 29042 node 11 1 ms
Sat Jan 31 05:31:15 2015 29042 node 11 1 ms
Sat Jan 31 05:31:15 2015 29042 node 11 1 ms
Sat Jan 31 05:31:15 2015 29042 node 11 1 ms
Sat Jan 31 05:31:15 2015 29042 node 11 1 ms
Sat Jan 31 05:31:15 2015 29042 node 11 1 ms
Sat Jan 31 05:31:15 2015 29042 node 11 2 ms
Sat Jan 31 05:31:15 2015 29042 node 11 3 ms
Sat Jan 31 05:31:15 2015 29042 node 11 2 ms
Sat Jan 31 05:31:15 2015 29042 node 11 1 ms
Sat Jan 31 05:31:15 2015 29042 node 11 1 ms
Sat Jan 31 05:31:15 2015 29042 node 11 1 ms
Sat Jan 31 05:31:15 2015 29042 node 11 1 ms
[...]
Duration (ns):
value |-------------------------------------------------- count
131072 | 0
262144 | 0
524288 | 1
1048576 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 138
2097152 |@@ 6
4194304 | 1
8388608 | 0
16777216 | 0
Most of these sessions were between 1 and 2 milliseconds in lifespan.
The socket lifespan is expected to represent the time taken by a server to
respond to a request. This time may include cycles on-CPU, and cycles off-CPU
blocked on another resource. Note that HTTP keep-alive sessions may have long
durations which process multiple requests.
accept2close-nd.stp accepts an optional argument: a minimum lifespan threshold
in milliseconds. For example, socket sessions that are 5 milliseconds and
longer:
# ./accept2close-nd.stp 5
Only tracing events slower than 5 ms.
TIME PID COMM FD DURATION
Sat Jan 31 05:36:23 2015 5236 node 11 5 ms
Sat Jan 31 05:37:39 2015 5236 node 11 5 ms
Sat Jan 31 05:37:50 2015 5236 node 11 9 ms
Sat Jan 31 05:38:09 2015 5236 node 11 7 ms
^C
Duration (ns):
value |-------------------------------------------------- count
1048576 | 0
2097152 | 0
4194304 |@@@ 3
8388608 |@ 1
16777216 | 0
33554432 | 0