4 Written by Jens Axboe <axboe@suse.de> (initial version and kernel support),
5 Alan D. Brunelle (threading and splitup into two seperate programs),
6 Nathan Scott <nathans@sgi.com> (bug fixes, process names, multiple devices)
12 You need to be running a 2.6.14-rc3 kernel or newer, with the blk-trace patch
13 included in this repository. If you forgot where you got it, the url is:
15 rsync://rsync.kernel.org/pub/scm/linux/kernel/git/axboe/blktrace.git
17 If you don't have git, you can get hourly snapshots from:
19 http://www.kernel.org/pub/linux/kernel/people/axboe/blktrace/
21 The snapshots include the full git object database as well. kernel.org has
22 excessively long mirror times, so if you have git installed, you can pull
25 git://brick.kernel.dk/data/git/blktrace.git
27 For browsing the repo over http and viewing history etc, you can direct
30 http://brick.kernel.dk/git
36 $ blktrace -d <dev> [ -r relay_path ] [ -o output ] [ -k ] [ -w time ]
37 [ -a action ] [ -A action mask ]
39 -d Use specified device. May also be given last after options.
40 -r Path to mounted relayfs, defaults to /relay.
41 -o File(s) to send output to.
42 -D Directory to prepend to output file names.
43 -k Kill running trace.
44 -w Stop after defined time, in seconds.
45 -a Only trace specific actions (use more -a options to add actions).
46 Available actions are:
59 -A Give the trace mask directly as a number.
61 -b Sub buffer size in KiB.
62 -n Number of sub buffers.
63 -l Run in network listen mode (blktrace server)
64 -h Run in network client mode, connecting to the given host
65 -p Network port to use (default 8462)
66 -s Make the network client use sendfile() to transfer data
67 -V Print program version info.
69 $ blkparse -i <input> [ -o <output> ] [ -b rb_batch ] [ -s ] [ -t ] [ -q ]
70 [ -w start:stop ] [ -f output format ] [ -F format spec ]
72 -i Input file containing trace data, or '-' for stdin.
73 -D Directory to prepend to input file names.
74 -o Output file. If not given, output is stdout.
75 -b stdin read batching.
76 -s Show per-program io statistics.
77 -h Hash processes by name, not pid.
78 -t Track individual ios. Will tell you the time a request took to
79 get queued, to get dispatched, and to get completed.
80 -q Quiet. Don't display any stats at the end of the trace.
81 -w Only parse data between the given time interval in seconds. If
82 'start' isn't given, blkparse defaults the start time to 0.
83 -f Output format. Customize the output format. The format field
88 %C - Task command name
95 %n - Number of sectors
100 %t - Time (wallclock - nanoseconds)
101 %T - Time (wallclock - seconds)
102 %u - Time (processing - microseconds)
105 -F Format specification. The individual specifiers are:
114 M - Both front and back merge
124 -v More verbose for marginal errors.
125 -V Print program version info.
127 $ verify_blkparse filename
129 Verifies an output file from blkparse. All it does is check if
130 the events in the file are correctly time ordered. If an entry
131 is found that isn't ordered, it's dumped to stdout.
133 $ blkrawverify <dev> [<dev>...]
135 The blkrawverify utility can be used to verify data retrieved
136 via blktrace. It will check for valid event formats, forward
137 progressing sequence numbers and time stamps, also does reasonable
138 checks for other potential issues within invidividual events.
140 Errors found will be tracked in <dev>.verify.out.
142 If you want to do live tracing, you can pipe the data between blktrace
145 % blktrace -d <device> -o - | blkparse -i -
147 This has a small risk of displaying some traces a little out of sync, since
148 it will do batch sorts of input events. Similarly, you can do traces over
149 the network. The network 'server' must run:
153 to listen to incoming blktrace connections, while the client should use
155 % blktrace -d /dev/sda -h <server hostname>
157 to connect and transfer data over the network.
163 A users guide is distributed with the source. It is in latex, a
164 'make docs' will build a PDF in doc/. You need tetex and latex installed
165 to build the document.
171 vger hosts a mailing list dedicated to btrace discussion and development.
172 The list is called linux-btrace@vger.kernel.org, subscribe by sending
173 a mail to majordomo@vger.kernel.org with 'subscribe linux-btrace' in
178 20051007, Jens Axboe <axboe@suse.de>