biotop - Block device (disk) I/O by process top. biotop [-h] [-C] [-r MAXROWS] [interval] [count] 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. CONFIG_BPF and bcc.

-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.

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: # biotop 5 10

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.

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. 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.

Linux Unstable - in development. Brendan Gregg top(1) by William LeFebvre biosnoop(8), biolatency(8), iostat(1)