Demonstrations of biotop, the Linux eBPF/bcc version.
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Short for block device I/O top, biotop summarizes which processes are
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performing disk I/O. It's top for disks. Sample output:
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# ./biotop
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Tracing... Output every 1 secs. Hit Ctrl-C to end
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08:04:11 loadavg: 1.48 0.87 0.45 1/287 14547
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PID COMM D MAJ MIN DISK I/O Kbytes AVGms
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14501 cksum R 202 1 xvda1 361 28832 3.39
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6961 dd R 202 1 xvda1 1628 13024 0.59
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13855 dd R 202 1 xvda1 1627 13016 0.59
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326 jbd2/xvda1-8 W 202 1 xvda1 3 168 3.00
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1880 supervise W 202 1 xvda1 2 8 6.71
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1873 supervise W 202 1 xvda1 2 8 2.51
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1871 supervise W 202 1 xvda1 2 8 1.57
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1876 supervise W 202 1 xvda1 2 8 1.22
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1892 supervise W 202 1 xvda1 2 8 0.62
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1878 supervise W 202 1 xvda1 2 8 0.78
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1886 supervise W 202 1 xvda1 2 8 1.30
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1894 supervise W 202 1 xvda1 2 8 3.46
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1869 supervise W 202 1 xvda1 2 8 0.73
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1888 supervise W 202 1 xvda1 2 8 1.48
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By default the screen refreshes every 1 second, and shows the top 20 disk
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consumers, sorted on total Kbytes. The first line printed is the header,
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which has the time and then the contents of /proc/loadavg.
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For the interval summarized by the output above, the "cksum" command performed
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361 disk reads to the "xvda1" device, for a total of 28832 Kbytes, with an
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average I/O time of 3.39 ms. Two "dd" processes were also reading from the
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same disk, which a higher I/O rate and lower latency. While the average I/O
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size is not printed, it can be determined by dividing the Kbytes column by
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the I/O column.
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The columns through to Kbytes show the workload applied. The final column,
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AVGms, shows resulting performance. Other bcc tools can be used to get more
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details when needed: biolatency and biosnoop.
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Many years ago I created the original "iotop", and later regretted not calling
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it diskiotop or blockiotop, as "io" alone is ambiguous. This time it is biotop.
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The -C option can be used to prevent the screen from clearing (my preference).
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Here's using it with a 5 second interval:
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# ./biotop -C 5
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Tracing... Output every 5 secs. Hit Ctrl-C to end
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08:09:44 loadavg: 0.42 0.44 0.39 2/282 22115
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PID COMM D MAJ MIN DISK I/O Kbytes AVGms
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22069 dd R 202 1 xvda1 5993 47976 0.33
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326 jbd2/xvda1-8 W 202 1 xvda1 3 168 2.67
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1866 svscan R 202 1 xvda1 33 132 1.24
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1880 supervise W 202 1 xvda1 10 40 0.56
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1873 supervise W 202 1 xvda1 10 40 0.79
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1871 supervise W 202 1 xvda1 10 40 0.78
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1876 supervise W 202 1 xvda1 10 40 0.68
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1892 supervise W 202 1 xvda1 10 40 0.71
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1878 supervise W 202 1 xvda1 10 40 0.65
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1886 supervise W 202 1 xvda1 10 40 0.78
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1894 supervise W 202 1 xvda1 10 40 0.80
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1869 supervise W 202 1 xvda1 10 40 0.91
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1888 supervise W 202 1 xvda1 10 40 0.63
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22069 bash R 202 1 xvda1 1 16 19.94
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9251 kworker/u16:2 W 202 16 xvdb 2 8 0.13
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08:09:49 loadavg: 0.47 0.44 0.39 1/282 22231
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PID COMM D MAJ MIN DISK I/O Kbytes AVGms
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22069 dd R 202 1 xvda1 13450 107600 0.35
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22199 cksum R 202 1 xvda1 941 45548 4.63
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326 jbd2/xvda1-8 W 202 1 xvda1 3 168 2.93
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24467 kworker/0:2 W 202 16 xvdb 1 64 0.28
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1880 supervise W 202 1 xvda1 10 40 0.81
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1873 supervise W 202 1 xvda1 10 40 0.81
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1871 supervise W 202 1 xvda1 10 40 1.03
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1876 supervise W 202 1 xvda1 10 40 0.76
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1892 supervise W 202 1 xvda1 10 40 0.74
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1878 supervise W 202 1 xvda1 10 40 0.94
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1886 supervise W 202 1 xvda1 10 40 0.76
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1894 supervise W 202 1 xvda1 10 40 0.69
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1869 supervise W 202 1 xvda1 10 40 0.72
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1888 supervise W 202 1 xvda1 10 40 1.70
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22199 bash R 202 1 xvda1 2 20 0.35
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482 xfsaild/md0 W 202 16 xvdb 5 13 0.27
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482 xfsaild/md0 W 202 32 xvdc 2 8 0.33
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31331 pickup R 202 1 xvda1 1 4 0.31
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08:09:54 loadavg: 0.51 0.45 0.39 2/282 22346
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PID COMM D MAJ MIN DISK I/O Kbytes AVGms
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22069 dd R 202 1 xvda1 14689 117512 0.32
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326 jbd2/xvda1-8 W 202 1 xvda1 3 168 2.33
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1880 supervise W 202 1 xvda1 10 40 0.65
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1873 supervise W 202 1 xvda1 10 40 1.08
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1871 supervise W 202 1 xvda1 10 40 0.66
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1876 supervise W 202 1 xvda1 10 40 0.79
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1892 supervise W 202 1 xvda1 10 40 0.67
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1878 supervise W 202 1 xvda1 10 40 0.66
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1886 supervise W 202 1 xvda1 10 40 1.02
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1894 supervise W 202 1 xvda1 10 40 0.88
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1869 supervise W 202 1 xvda1 10 40 0.89
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1888 supervise W 202 1 xvda1 10 40 1.25
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08:09:59 loadavg: 0.55 0.46 0.40 2/282 22461
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PID COMM D MAJ MIN DISK I/O Kbytes AVGms
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22069 dd R 202 1 xvda1 14442 115536 0.33
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326 jbd2/xvda1-8 W 202 1 xvda1 3 168 3.46
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1880 supervise W 202 1 xvda1 10 40 0.87
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1873 supervise W 202 1 xvda1 10 40 0.87
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1871 supervise W 202 1 xvda1 10 40 0.78
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1876 supervise W 202 1 xvda1 10 40 0.86
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1892 supervise W 202 1 xvda1 10 40 0.89
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1878 supervise W 202 1 xvda1 10 40 0.87
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1886 supervise W 202 1 xvda1 10 40 0.86
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1894 supervise W 202 1 xvda1 10 40 1.06
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1869 supervise W 202 1 xvda1 10 40 1.12
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1888 supervise W 202 1 xvda1 10 40 0.98
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08:10:04 loadavg: 0.59 0.47 0.40 3/282 22576
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PID COMM D MAJ MIN DISK I/O Kbytes AVGms
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22069 dd R 202 1 xvda1 14179 113432 0.34
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326 jbd2/xvda1-8 W 202 1 xvda1 3 168 2.39
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1880 supervise W 202 1 xvda1 10 40 0.81
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1873 supervise W 202 1 xvda1 10 40 1.02
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1871 supervise W 202 1 xvda1 10 40 1.15
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1876 supervise W 202 1 xvda1 10 40 1.10
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1892 supervise W 202 1 xvda1 10 40 0.77
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1878 supervise W 202 1 xvda1 10 40 0.72
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1886 supervise W 202 1 xvda1 10 40 0.81
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1894 supervise W 202 1 xvda1 10 40 0.86
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1869 supervise W 202 1 xvda1 10 40 0.83
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1888 supervise W 202 1 xvda1 10 40 0.79
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24467 kworker/0:2 R 202 32 xvdc 3 12 0.26
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1056 cron R 202 1 xvda1 2 8 0.30
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24467 kworker/0:2 R 202 16 xvdb 1 4 0.23
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08:10:09 loadavg: 0.54 0.46 0.40 2/281 22668
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PID COMM D MAJ MIN DISK I/O Kbytes AVGms
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22069 dd R 202 1 xvda1 250 2000 0.34
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326 jbd2/xvda1-8 W 202 1 xvda1 3 168 2.40
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1880 supervise W 202 1 xvda1 8 32 0.93
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1873 supervise W 202 1 xvda1 8 32 0.76
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1871 supervise W 202 1 xvda1 8 32 0.60
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1876 supervise W 202 1 xvda1 8 32 0.61
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1892 supervise W 202 1 xvda1 8 32 0.68
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1878 supervise W 202 1 xvda1 8 32 0.90
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1886 supervise W 202 1 xvda1 8 32 0.57
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1894 supervise W 202 1 xvda1 8 32 0.97
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1869 supervise W 202 1 xvda1 8 32 0.69
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1888 supervise W 202 1 xvda1 8 32 0.67
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This shows another "dd" command reading from xvda1. On this system, various
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"supervise" processes do 8 disk writes per second, every second (they are
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creating and updating "status" files).
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USAGE message:
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# ./biotop.py -h
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usage: biotop.py [-h] [-C] [-r MAXROWS] [interval] [count]
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Block device (disk) I/O by process
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positional arguments:
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interval output interval, in seconds
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count number of outputs
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optional arguments:
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-h, --help show this help message and exit
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-C, --noclear don't clear the screen
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-r MAXROWS, --maxrows MAXROWS
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maximum rows to print, default 20
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examples:
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./biotop # block device I/O top, 1 second refresh
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./biotop -C # don't clear the screen
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./biotop 5 # 5 second summaries
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./biotop 5 10 # 5 second summaries, 10 times only
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