The following is an example of the writedist.d script,
Here the writedist.d script is run for a few seconds, then Ctrl-C is hit,
# writedist.d
dtrace: description 'sysinfo:::writech ' matched 4 probes
^C
[...]
Xorg
value ------------- Distribution ------------- count
16 | 0
32 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 169
64 |@@@ 16
128 |@@ 10
256 | 0
gnome-terminal
value ------------- Distribution ------------- count
0 | 0
1 |@@ 6
2 | 0
4 | 0
8 | 1
16 |@ 2
32 |@@@ 7
64 | 0
128 |@@@@@@@@@@@@@@@@@@@@@@@ 63
256 |@@@@ 10
512 | 1
1024 |@@@@@ 13
2048 |@ 2
4096 |@@@ 7
This allows us to understand the write behaviour of each process. The
gnome-terminal command has executed 6 writes that returned 0 bytes, through
to 7 writes that were at least 4096 bytes (up to 8192).