BLKIOMON(8)BLKIOMON(8)NAME
blkiomon - monitor block device I/O based o blktrace data
SYNOPSIS
blkiomon -I interval [ -h file ] [ -b file ] [ -D file ] [ -Q path_name -q msg_queue_id -m msg_id ] [ -V ]
DESCRIPTION
blkiomon is a block device I/O monitor. It periodically generates per-device request size and request latency statistics from blktrace
data. It provides histograms as well as data that can be used to calculate min, max, average and variance. For this purpose, it consumes D
and C traces read from stdin.
There are options for binary output and human-readable output to files and stdout. Output to a message queue is supported as well.
There is no need to use blkparse with blkiomon. blkiomon is capable of consuming binary output written to stdout by blktrace.
OPTIONS -I interval
--interval=interval
Set sample interval
-h file
--human-readable=file
Human-readable output file. Use '-' for stdout.
-b file
--binary=file
Binary output file. Use '-' for stdout.
-D file
--debug=file
Output file for debugging data. Use '-' for stdout.
-Q path_name
--msg-queue=path_name
Sets path_name as path name for existing message queue to be used for binary output.
-q msg_queue_id
--msg-queue-id=msg_queue_id
Sets msg_queue_id as ID for an existing message queue to be used for binary output.
-m msg_id
--msg-id=msg_id
Sets msg_id as message identifier to be used for binary output messages written to an existing message queue.
-V
--version
Print program version.
EXAMPLES
To get I/O statistics for /dev/sdw every 10 seconds for a period of one hour, use the following command:
% blktrace /dev/sdw -a issue -a complete -w 3600 -o - | blkiomon -I 10 -h -
AUTHORS
blkiomon and this man page were written by Martin Peschke.
REPORTING BUGS
Report bugs to <linux-btrace@vger.kernel.org>
COPYRIGHT
Copyright (C) 2008 IBM Corp.
This is free software. You may redistribute copies of it under the terms of the GNU General Public License
<http://www.gnu.org/licenses/gpl.html>. There is NO WARRANTY, to the extent permitted by law.
SEE ALSO
btrace (8), blktrace (8), blkparse (1), verify_blkparse (1), blkrawverify (1), btt (1)
July 17, 2008 BLKIOMON(8)
Check Out this Related Man Page
BLKTRACE(8)BLKTRACE(8)NAME
blktrace - generate traces of the i/o traffic on block devices
SYNOPSIS
blktrace -d dev [ -r debugfs_path ] [ -o output ] [-k ] [ -w time ] [ -a action ] [ -A action_mask ] [ -v ]
DESCRIPTION
blktrace is a block layer IO tracing mechanism which provides detailed information about request queue operations up to user space. There
are three major components: a kernel component, a utility to record the i/o trace information for the kernel to user space, and utilities
to analyse and view the trace information. This man page describes blktrace, which records the i/o event trace information for a specific
block device to a file.
The blktrace utility extracts event traces from the kernel (via the relaying through the debug file system). Some background details con-
cerning the run-time behaviour of blktrace will help to understand some of the more arcane command line options:
- blktrace receives data from the kernel in buffers passed up through the debug file system (relay). Each device being traced has a file
created in the mounted directory for the debugfs, which defaults to /sys/kernel/debug -- this can be overridden with the -r command line
argument.
- blktrace defaults to collecting all events that can be traced. To limit the events being captured, you can specify one or more filter
masks via the -a option.
Alternatively, one may specify the entire mask utilising a hexadecimal value that is version-specific. (Requires understanding of the
internal representation of the filter mask.)
- As noted above, the events are passed up via a series of buffers stored into debugfs files. The size and number of buffers can be speci-
fied via the -b and -n arguments respectively.
- blktrace stores the extracted data into files stored in the local directory. The format of the file names is (by default) device.blk-
trace.cpu, where device is the base device name (e.g, if we are tracing /dev/sda, the base device name would be sda); and cpu identifies
a CPU for the event stream.
The device portion of the event file name can be changed via the -o option.
- blktrace may also be run concurrently with blkparse to produce live output -- to do this specify -o - for blktrace.
- The default behaviour for blktrace is to run forever until explicitly killed by the user (via a control-C, or kill utility invocation).
There are two ways to modify this:
1. You may utilise the blktrace utility itself to kill a running trace -- via the -k option.
2. You can specify a run-time duration for blktrace via the -w option -- then blktrace will run for the specified number of seconds, and
then halt.
OPTIONS -A hex-mask
--set-mask=hex-mask
Set filter mask to hex-mask (see below for masks)
-a mask
--act-mask=mask
Add mask to current filter (see below for masks)
-b size
--buffer-size=size
Specifies buffer size for event extraction (scaled by 1024). The default buffer size is 512KiB.
-d dev
--dev=dev
Adds dev as a device to trace
-I file
--input-devs=file
Adds the devices found in file as devices to trace
-k
--kill
Kill on-going trace
-n num-sub
--num-sub=num-sub
Specifies number of buffers to use. blktrace defaults to 4 sub buffers.
-o file
--output=file
Prepend file to output file name(s)
-r rel-path
--relay=rel-path
Specifies debugfs mount point
-V
--version Outputs version
-w seconds
--stopwatch=seconds
Sets run time to the number of seconds specified
FILTER MASKS
The following masks may be passed with the -a command line option, multiple filters may be combined via multiple -a command line options.
barrier: barrier attribute
complete: completed by driver
fs: requests
issue: issued to driver
pc: packet command events
queue: queue operations
read: read traces
requeue: requeue operations
sync: synchronous attribute
write: write traces
notify: trace messages
REQUEST TYPES
blktrace distinguishes between two types of block layer requests, file system and SCSI commands. The former are dubbed fs requests, the
latter pc requests. File system requests are normal read/write operations, i.e. any type of read or write from a specific disk location at
a given size. These requests typically originate from a user process, but they may also be initiated by the vm flushing dirty data to disk
or the file system syncing a super or journal block to disk. pc requests are SCSI commands. blktrace sends the command data block as a pay-
load so that blkparse can decode it.
EXAMPLES
To trace the i/o on the device /dev/hda and parse the output to human readable form, use the following command:
% blktrace -d /dev/sda -o - | blkparse -i -
This same behaviour can be achieve with the convenience script btrace. The command
% btrace /dev/sda
has exactly the same effect as the previous command. See btrace (8) for more information.
To trace the i/o on a device and save the output for later processing with blkparse, use blktrace like this:
% blktrace /dev/sda /dev/sdb
This will trace i/o on the devices /dev/sda and /dev/sdb and save the recorded information in the files sda and sdb in the current direc-
tory, for the two different devices, respectively. This trace information can later be parsed by the blkparse utility:
% blkparse sda sdb
which will output the previously recorded tracing information in human readable form to stdout. See blkparse (1) for more information.
AUTHORS
blktrace was written by Jens Axboe, Alan D. Brunelle and Nathan Scott. This man page was created from the blktrace documentation by Bas
Zoetekouw.
REPORTING BUGS
Report bugs to <linux-btrace@vger.kernel.org>
COPYRIGHT
Copyright (C) 2006 Jens Axboe, Alan D. Brunelle and Nathan Scott.
This is free software. You may redistribute copies of it under the terms of the GNU General Public License
<http://www.gnu.org/licenses/gpl.html>. There is NO WARRANTY, to the extent permitted by law.
This manual page was created for Debian by Bas Zoetekouw. It was derived from the documentation provided by the authors and it may be
used, distributed and modified under the terms of the GNU General Public License, version 2.
On Debian systems, the text of the GNU General Public License can be found in /usr/share/common-licenses/GPL-2.
SEE ALSO
btrace (8), blkparse (1), verify_blkparse (1), blkrawverify (1), btt (1)
blktrace git-20070306202522 March 6, 2007 BLKTRACE(8)