bitesize-nd.8

.TH bitesize-nd 8  "2015-01-30" "USER COMMANDS"
.SH NAME
bitesize-nd \- Measure block I/O size distribution. Uses Linux SystemTap (non-debuginfo).
.SH SYNOPSIS
.B bitesize-nd.stp
.SH DESCRIPTION
This uses the kernel tracepoint block_rq_insert to read the size of I/O. The
output includes the name of the process or thread that was on-CPU when the I/O
request was inserted on the issue queue.
.SH REQUIREMENTS
SystemTap.
.SH EXAMPLES
.TP
Measure block I/O sizes, and show a distribution histogram for each process name on Ctrl-C:
#
.B bitesize-nd.stp
.SH FIELDS
.TP
value
The minimum size, in bytes, for this histogram bucket. Read this value
as "I/O size was at least xxx".
.TP
count
How many I/O fell into this size range.
.SH OVERHEAD
Should be low, relative to the rate of disk I/O. Test first.
.SH SOURCE
This is from the SystemTap lwtools collection.
.IP
https://github.com/brendangregg/systemtap-lwtools
.PP
Also look under the examples directory for a text file containing example
usage, output, and commentary for this tool.
.SH OS
Linux
.SH STABILITY
Unstable - in development.
.SH AUTHOR
Brendan Gregg
.SH SEE ALSO
biolatency-nd.stp(8), iostat(1)