.TH bitesize 8  "2016-02-05" "USER COMMANDS"
.SH NAME
bitesize \- Summarize block device I/O size as a histogram \- Linux eBPF/bcc.
.SH SYNOPSIS
.B bitesize
.SH DESCRIPTION
Show I/O distribution for requested block sizes, by process name.

This works by tracing block:block_rq_issue and prints a historgram of I/O size.

Since this uses BPF, only the root user can use this tool.
.SH REQUIREMENTS
CONFIG_BPF and bcc.
.SH EXAMPLES
.TP
Count I/O size per process until Ctrl-C is hit:
#
.B bitesize
.SH FIELDS
.TP
Kbtes
Size in kilobytes of range
.TP
count
How many I/O fell into this range
.TP
distribution
An ASCII bar chart to visualize the distribution (count column)

.SH OVERHEAD
This traces a block I/O tracepoint to update a histogram, which is
asynchronously copied to user-space. This method is very efficient, and 
the overhead for most storage I/O rates (< 10k IOPS) should be negligible. 
If you have a higher IOPS storage environment, test and quantify the overhead 
before use.

.SH SOURCE
This is from bcc.
.IP
https://github.com/iovisor/bcc
.PP
Also look in the bcc distribution for a companion _examples.txt file containing
example usage, output, and commentary for this tool.
.SH OS
Linux
.SH STABILITY
Unstable - in development.
.SH AUTHOR
Allan McAleavy
.SH SEE ALSO
https://github.com/brendangregg/systemtap-lwtools/blob/master/disk/bitesize-nd.stp