biotop - Block device (disk) I/O by process top.

       Brendan Gregg, Rocky Xing

       This is top for disks.

       This  traces  block device I/O (disk I/O), and prints a per-process summary every interval (by default, 1
       second). The summary is sorted on the top disk consumers by throughput (Kbytes). The PID and process name
       shown are measured from when the I/O was first created, which usually identifies the responsible process.

       For efficiency, this uses in-kernel eBPF maps to cache process details (PID and comm) by I/O request,  as
       well as a starting timestamp for calculating I/O latency, and the final summary.

       This  works  by tracing various kernel blk_*() functions using dynamic tracing, and will need updating to
       match any changes to these functions.

       Since this uses BPF, only the root user can use this tool.

       Summarize block device I/O by process, 1 second screen refresh:
              # biotop

       Don't clear the screen:
              # biotop-C

       5 second summaries, 10 times only:
              # biotop510

       loadavg:
              The contents of /proc/loadavg

       PID    Cached process ID, if present. This usually (but isn't guaranteed)  to  identify  the  responsible
              process for the I/O.

       COMM   Cached  process  name, if present. This usually (but isn't guaranteed) to identify the responsible
              process for the I/O.

       D      Direction: R == read, W == write. This is a simplification.

       MAJ    Major device number.

       MIN    Minor device number.

       DISK   Disk device name.

       I/O    Number of I/O during the interval.

       Kbytes Total Kbytes for these I/O, during the interval.

       AVGms  Average time for the  I/O  (latency)  from  the  issue  to  the  device,  to  its  completion,  in
              milliseconds.

top(1) by William LeFebvre

       biotop - Block device (disk) I/O by process top.

       -C     Don't clear the screen.

       -r MAXROWS
              Maximum number of rows to print. Default is 20.

       -p PID Trace this PID only.

       interval
              Interval between updates, seconds.

       count  Number of interval summaries.

       Linux

       Since block device I/O usually has a relatively low frequency (< 10,000/s), the overhead for this tool is
       expected to be low or negligible. For high IOPS storage systems, test and quantify before use.

       CONFIG_BPF and bcc.

biosnoop(8), biolatency(8), iostat(1)

USER COMMANDS                                      2016-02-06                                          biotop(8)

       This is from bcc.

              https://github.com/iovisor/bcc

       Also  look  in  the bcc distribution for a companion _examples.txt file containing example usage, output,
       and commentary for this tool.

       Unstable - in development.

biotop[-h][-C][-rMAXROWS][-pPID][interval][count]