| .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 |
