1BLKPARSE(1) BLKPARSE(1)
2
6 blkparse - produce formatted output of event streams of block devices
7
11 blkparse [ options ]
12
16 The blkparse utility will attempt to combine streams of events for var‐
17 ious devices on various CPUs, and produce a formatted output of the
18 event information. Specifically, it will take the (machine-readable)
19 output of the blktrace utility and convert it to a nicely formatted and
20 human-readable form.
21 As with blktrace, some details concerning blkparse will help in under‐
23 standing the command line options presented below.
24 - By default, blkparse expects to run in a post-processing mode; one
28 where the trace events have been saved by a previous run of blktrace,
29 and blkparse is combining event streams and dumping formatted data.
30 blkparse may be run in a live manner concurrently with blktrace by
32 specifying -i - to blkparse, and combining it with the live option
33 for blktrace. An example would be:
34 % blktrace -d /dev/sda -o - | blkparse -i -
36 - You can set how many blkparse batches event reads via the -b option,
39 the default is to handle events in batches of 512.
40 - If you have saved event traces in blktrace with different output
43 names (via the -o option to blktrace), you must specify the same
44 input name via the -i option.
45 - The format of the output data can be controlled via the -f or -F
48 options -- see OUTPUT DESCRIPTION AND FORMATTING for details.
49 By default, blkparse sends formatted data to standard output. This may
52 be changed via the -o option, or text output can be disabled via the -O
53 option. A merged binary stream can be produced using the -d option.
54
59 -A hex-mask
60 --set-mask=hex-mask
61 Set filter mask to hex-mask, see blktrace (8) for masks
62 -a mask
64 --act-mask=mask
65 Add mask to current filter, see blktrace (8) for masks
66 -D dir
68 --input-directory=dir
69 Prepend dir to input file names
70 -b batch
72 --batch={batch}
73 Standard input read batching
74 -i file
76 --input=file
77 Specifies base name for input files -- default is device.blk‐
78 trace.cpu.
79 As noted above, specifying -i - runs in live mode with blktrace
81 (reading data from standard in).
82 -F typ,fmt
84 --format=typ,fmt
85 -f fmt
86 --format-spec=fmt
87 Sets output format (See OUTPUT DESCRIPTION AND FORMATTING for
88 details.)
89 The -f form specifies a format for all events
91 The -F form allows one to specify a format for a specific event
93 type. The single-character typ field is one of the action speci‐
94 fiers described in ACTION IDENTIFIERS.
95 -M
97 --no-msgs
98 When -d is specified, this will stop messages from being output
99 to the file. (Can seriously reduce the size of the resultant
100 file when using the CFQ I/O scheduler.)
101 -h
103 --hash-by-name
104 Hash processes by name, not by PID
105 -o file
107 --output=file
108 Output file
109 -O
111 --no-text-output
112 Do not produce text output, used for binary (-d) only
113 -d file
115 --dump-binary=file
116 Binary output file
117 -q
119 --quiet
120 Quiet mode
121 -s
123 --per-program-stats
124 Displays data sorted by program
125 -t
127 --track-ios
128 Display time deltas per IO
129 -w span
131 --stopwatch=span
132 Display traces for the span specified -- where span can be:
133 end-time -- Display traces from time 0 through end-time (in ns)
134 or
135 start:end-time -- Display traces from time start through
136 end-time (in ns).
137 -v
139 --verbose
140 More verbose marginal on marginal errors
141 -V
143 --version
144 Display version
145
149 The following trace actions are recognised:
150 C -- complete A previously issued request has been completed. The out‐
153 put will detail the sector and size of that request, as well as the
154 success or failure of it.
155 D -- issued A request that previously resided on the block layer queue
158 or in the i/o scheduler has been sent to the driver.
159 I -- inserted A request is being sent to the i/o scheduler for addition
162 to the internal queue and later service by the driver. The request
163 is fully formed at this time.
164 Q -- queued This notes intent to queue i/o at the given location. No
167 real requests exists yet.
168 B -- bounced The data pages attached to this bio are not reachable by
171 the hardware and must be bounced to a lower memory location. This
172 causes a big slowdown in i/o performance, since the data must be
173 copied to/from kernel buffers. Usually this can be fixed with using
174 better hardware -- either a better i/o controller, or a platform
175 with an IOMMU.
176 M -- back merge A previously inserted request exists that ends on the
179 boundary of where this i/o begins, so the i/o scheduler can merge
180 them together.
181 F -- front merge Same as the back merge, except this i/o ends where a
184 previously inserted requests starts.
185 M --front or back merge One of the above
188 M -- front or back merge One of the above.
191 G -- get request To send any type of request to a block device, a
194 struct request container must be allocated first.
195 S -- sleep No available request structures were available, so the
198 issuer has to wait for one to be freed.
199 P -- plug When i/o is queued to a previously empty block device queue,
202 Linux will plug the queue in anticipation of future ios being added
203 before this data is needed.
204 U -- unplug Some request data already queued in the device, start send‐
207 ing requests to the driver. This may happen automatically if a
208 timeout period has passed (see next entry) or if a number of
209 requests have been added to the queue.
210 T -- unplug due to timer If nobody requests the i/o that was queued
213 after plugging the queue, Linux will automatically unplug it after
214 a defined period has passed.
215 X -- split On raid or device mapper setups, an incoming i/o may strad‐
218 dle a device or internal zone and needs to be chopped up into
219 smaller pieces for service. This may indicate a performance problem
220 due to a bad setup of that raid/dm device, but may also just be
221 part of normal boundary conditions. dm is notably bad at this and
222 will clone lots of i/o.
223 A -- remap For stacked devices, incoming i/o is remapped to device
226 below it in the i/o stack. The remap action details what exactly is
227 being remapped to what.
228
234 The output from blkparse can be tailored for specific use -- in partic‐
235 ular, to ease parsing of output, and/or limit output fields to those
236 the user wants to see. The data for fields which can be output include:
237 a Action, a (small) string (1 or 2 characters) -- see table below for
240 more details
241 c CPU id
244 C Command
247 d RWBS field, a (small) string (1-3 characters) -- see section below
250 for more details
251 D 7-character string containing the major and minor numbers of the
254 event's device (separated by a comma).
255 e Error value
258 m Minor number of event's device.
261 M Major number of event's device.
264 n Number of blocks
267 N Number of bytes
270 p Process ID
273 P Display packet data -- series of hexadecimal values
276 s Sequence numbers
279 S Sector number
282 t Time stamp (nanoseconds)
285 T Time stamp (seconds)
288 u Elapsed value in microseconds (-t command line option)
291 U Payload unsigned integer
294 Note that the user can optionally specify field display width, and
297 optionally a left-aligned specifier. These precede field specifiers,
298 with a '%' character, followed by the optional left-alignment specifier
299 (-) followed by the width (a decimal number) and then the field.
300 Thus, to specify the command in a 12-character field that is left
302 aligned:
303 -f "%-12C"
305
309 The following table shows the various actions which may be output:
310 A IO was remapped to a different device
313 B IO bounced
316 C IO completion
319 D IO issued to driver
322 F IO front merged with request on queue
325 G Get request
328 I IO inserted onto request queue
331 M IO back merged with request on queue
334 P Plug request
337 Q IO handled by request queue code
340 S Sleep request
343 T Unplug due to timeout
346 U Unplug request
349 X Split
352
356 This is a small string containing at least one character ('R' for read,
357 'W' for write, or 'D' for block discard operation), and optionally
358 either a 'B' (for barrier operations) or 'S' (for synchronous opera‐
359 tions).
360
364 The standard header (or initial fields displayed) include:
365 "%D %2c %8s %5T.%9t %5p %2a %3d"
367 Breaking this down:
369 %D Displays the event's device major/minor as: %3d,%-3d.
372 %2c CPU ID (2-character field).
375 %8s Sequence number
378 %5T.%9t
381 5-character field for the seconds portion of the time stamp and
382 a 9-character field for the nanoseconds in the time stamp.
383 %5p 5-character field for the process ID.
386 %2a 2-character field for one of the actions.
389 %3d 3-character field for the RWBS data.
392 Seeing this in action:
394 8,0 3 1 0.000000000 697 G W 223490 + 8
396 [kjournald]
397 The header is the data in this line up to the 223490 (starting
399 block). The default output for all event types includes this
400 header.
401
406 C -- complete
407 If a payload is present, this is presented between parenthesis fol‐
408 lowing the header, followed by the error value.
409 If no payload is present, the sector and number of blocks are pre‐
411 sented (with an intervening plus (+) character). If the -t option
412 was specified, then the elapsed time is presented. In either case,
413 it is followed by the error value for the completion.
414 B -- bounced
416 D -- issued
417 I -- inserted
418 Q -- queued
419 If a payload is present, the number of payload bytes is output,
420 followed by the payload in hexadecimal between parenthesis.
421 If no payload is present, the sector and number of blocks are pre‐
423 sented (with an intervening plus (+) character). If the -t option
424 was specified, then the elapsed time is presented (in parenthesis).
425 In either case, it is followed by the command associated with the
426 event (surrounded by square brackets).
427 F -- front merge
429 G -- get request
430 M -- back merge
431 S -- sleep
432 The starting sector and number of blocks is output (with an inter‐
433 vening plus (+) character), followed by the command associated with
434 the event (surrounded by square brackets).
435 P -- plug
437 The command associated with the event (surrounded by square brack‐
438 ets) is output.
439 U -- unplug
441 T -- unplug due to timer
442 The command associated with the event (surrounded by square brack‐
443 ets) is output, followed by the number of requests outstanding.
444 X -- split
446 The original starting sector followed by the new sector (separated
447 by a slash (/) is output, followed by the command associated with
448 the event (surrounded by square brackets).
449 A -- remap
451 Sector and length is output, along with the original device and
452 sector offset.
453
457 To trace the i/o on the device /dev/sda and parse the output to human
458 readable form, use the following command:
459 % blktrace -d /dev/sda -o - | blkparse -i -
461 (see blktrace (8) for more information). This same behaviour can be
463 achieve with the convenience script btrace. The command
464 % btrace /dev/sda
466 has exactly the same effect as the previous command. See btrace (8) for
468 more information.
469 To trace the i/o on a device and save the output for later processing
471 with blkparse, use blktrace like this:
472 % blktrace /dev/sda /dev/sdb
474 This will trace i/o on the devices /dev/sda and /dev/sdb and save the
476 recorded information in the files sda and sdb in the current directory,
477 for the two different devices, respectively. This trace information
478 can later be parsed by the blkparse utility:
479 % blkparse sda sdb
481 which will output the previously recorded tracing information in human
483 readable form to stdout.
484
488 blkparse was written by Jens Axboe, Alan D. Brunelle and Nathan Scott.
489 This man page was created from the blktrace documentation by Bas
490 Zoetekouw.
491
495 Report bugs to <linux-btrace@vger.kernel.org>
496
499 Copyright © 2006 Jens Axboe, Alan D. Brunelle and Nathan Scott.
500 This is free software. You may redistribute copies of it under the
501 terms of the GNU General Public License
502 <http://www.gnu.org/licenses/gpl.html>. There is NO WARRANTY, to the
503 extent permitted by law.
504 This manual page was created for Debian by Bas Zoetekouw. It was
505 derived from the documentation provided by the authors and it may be
506 used, distributed and modified under the terms of the GNU General Pub‐
507 lic License, version 2.
508 On Debian systems, the text of the GNU General Public License can be
509 found in /usr/share/common-licenses/GPL-2.
510
513 btrace (8), blktrace (8), verify_blkparse (1), blkrawverify (1), btt
514 (1)
515blktrace git-20070306202522 March 6, 2007 BLKPARSE(1)