Current File : //usr/share/doc/bpfcc-tools/examples/tracing/disksnoop_example.txt
Demonstrations of disksnoop.py, the Linux eBPF/bcc version.
This traces block I/O, a prints a line to summarize each I/O completed:
# ./disksnoop.py
TIME(s) T BYTES LAT(ms)
16458043.435457 W 4096 2.73
16458043.435981 W 4096 3.24
16458043.436012 W 4096 3.13
16458043.437326 W 4096 4.44
16458044.126545 R 4096 42.82
16458044.129872 R 4096 3.24
16458044.130705 R 4096 0.73
16458044.142813 R 4096 12.01
16458044.147302 R 4096 4.33
16458044.148117 R 4096 0.71
16458044.148950 R 4096 0.70
16458044.164332 R 4096 15.29
16458044.168003 R 4096 3.58
16458044.171676 R 4096 3.59
16458044.172453 R 4096 0.72
16458044.173213 R 4096 0.71
16458044.173989 R 4096 0.72
16458044.174739 R 4096 0.70
16458044.190334 R 4096 15.52
16458044.196608 R 4096 6.17
16458044.203091 R 4096 6.35
The output includes a basic timestamp (in seconds), the type of I/O (W == write,
R == read, M == metadata), the size of the I/O in bytes, and the latency (or
duration) of the I/O in milliseconds.
The latency is measured from I/O request to the device, to the device
completion. This excludes latency spent queued in the OS.
Most of the I/O in this example were 0.7 and 4 milliseconds in duration. There
was an outlier of 42.82 milliseconds, a read which followed many writes (the
high latency may have been caused by the writes still being serviced on the
storage device).
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