SIMPLE SOLUTIONS

BIOTOP-BPFCC(8) - Linux man page online | Administration and privileged commands

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

Chapter
2016-02-06
biotop(8) System Manager's Manual biotop(8)

NAME

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

SYNOPSIS

biotop [-h] [-C] [-r MAXROWS] [interval] [count]

DESCRIPTION

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.

REQUIREMENTS

CONFIG_BPF and bcc.

OPTIONS

-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.

EXAMPLES

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

FIELDS

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.

OVERHEAD

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.

SOURCE

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.

OS

Linux

STABILITY

Unstable - in development.

AUTHOR

Brendan Gregg

INSPIRATION

top(1) by William LeFebvre

SEE ALSO

biosnoop(8), biolatency(8), iostat(1)
USER COMMANDS 2016-02-06 biotop(8)
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