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233 lines
6.4 KiB
233 lines
6.4 KiB
.TH BTREPLAY 8 "December 8, 2007" "blktrace git\-20071207142532" "" |
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.SH NAME |
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btreplay \- recreate IO loads recorded by blktrace |
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.SH SYNOPSIS |
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.B btreplay [ \fIoptions\fR ] <\fIdev\fR...> |
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.SH DESCRIPTION |
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.P |
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The \fIbtrecord\fR and \fIbtreplay\fR tools provide the ability to |
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record and replay IOs captured by the \fIblktrace\fR utility. Attempts |
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are made to maintain ordering, CPU mappings and time-separation of IOs. |
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.P |
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The \fIblktrace\fR utility provides the ability to collect detailed |
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traces from the kernel for each IO processed by the block IO layer. The |
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traces provide a complete timeline for each IO processed, including |
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detailed information concerning when an IO was first received by the block |
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IO layer \(em indicating the device, CPU number, time stamp, IO direction, |
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sector number and IO size (number of sectors). Using this information, |
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one is able to \fBreplay\fR the IO again on the same machine or another |
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set up entirely. |
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.P |
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The basic operating work-flow to replay IOs would be something like: |
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.IP \- 2 |
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Run \fIblktrace\fR to collect traces. Here you specify the |
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device or devices that you wish to trace and later replay IOs upon. Note: |
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the only traces you are interested in are \fBQUEUE\fR requests \(em |
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thus, to save system resources (including storage for traces), one could |
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specify the \fI-a queue\fR command line option to \fIblktrace\fR. |
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.IP \- 2 |
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While \fIblktrace\fR is running, you run the workload that you |
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are interested in. |
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.IP \- 2 |
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When the work load has completed, you stop the \fIblktrace\fR |
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utility (thus saving all traces over the complete workload). |
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.IP \- 2 |
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You extract the pertinent IO information from the traces saved by |
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\fIblktrace\fR using the \fIbtrecord\fR utility. This will parse |
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each trace file created by \fIblktrace\fR, and crafty IO descriptions |
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to be used in the next phase of the workload processing. |
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.IP \- 2 |
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Once \fIbtrecord\fR has successfully created a series of data |
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files to be processed, you can run the \fIbtreplay\fR utility which |
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attempts to generate the same IOs seen during the sample workload phase. |
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.SH OPTIONS |
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\-c <\fInum\fR> |
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.br |
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\-\-cpus=<\fInum\fR> |
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.RS |
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Set number of CPUs to use. |
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.RE |
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\-d <\fIdir\fR> |
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.br |
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\-\-input\-directory=<\fIdir\fR> |
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.RS |
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Set input directory. |
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This option requires a single parameter providing the directory |
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name for where input files are to be found. The default directory is the |
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current directory (\fI.\fR). |
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.RE |
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\-F |
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.br |
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\-\-find\-records |
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.RS |
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Find record files automatically |
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This option instructs \fIbtreplay\fR to go find all the record files in the |
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directory specified (either via the \fI-d\fR option, or in the default |
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directory (\fI.\fR). |
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.RE |
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\-h |
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.br |
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\-\-help |
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.RS |
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Show help and exit. |
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.RE |
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\-i <\fIbasename\fR> |
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.br |
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\-\-input\-base=<\fIbasename\fR> |
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.RS |
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Set base name for input files. |
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Each input file has 3 fields: |
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.IP 1. 3 |
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Device identifier (taken directly from the device name of the |
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\fIblktrace\fR output file). |
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.IP 2. 3 |
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\fIbtrecord\fR base name \(em by default ``replay''. |
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.IP 3. 3 |
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The CPU number (again, taken directly from the |
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\fIblktrace\fR output file name). |
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.P |
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This option requires a single parameter that will override the default name |
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(replay), and replace it with the specified value. |
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.RE |
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\-I <\fInum\fR> |
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.br |
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\-\-iterations=<\fInum\fR> |
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.RS |
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Set number of iterations to run. |
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This option requires a single parameter which specifies the number of times |
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to run through the input files. The default value is 1 |
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.RE |
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\-M <\fIfilename\fR> |
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.br |
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\-\-map\-devs=<\fIfilename\fR> |
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.RS |
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Specify device mappings. |
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This option requires a single parameter which specifies the name of a |
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file contain device mappings. The file must be very simply managed, with |
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just two pieces of data per line: |
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.IP \- 2 |
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The device name on the recorded system (with the '\fI/dev/\fR' |
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removed). Example: \fI/dev/sda\fR would just be \fIsda\fR. |
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.IP \- 2 |
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The device name on the replay system to use (again, without the |
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'\fI/dev/\fR' path prepended). |
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.P |
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An example file for when one would map devices \fI/dev/sda\fR and |
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\fI/dev/sdb\fR on the recorded system to \fIdev/sdg\fR and |
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\fIsdh\fR on the replay system would be: |
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.nf |
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.IP |
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sda sdg |
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sdb sdh |
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.fi |
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.P |
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The only entries in the file that are allowed are these two element lines \(em |
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we do not (yet?) support the notion of blank lines, or comment lines, or the |
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like. |
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.P |
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The utility allows for multiple \fI-M\fR options to be |
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supplied on the command line. |
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.RE |
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\-N |
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.br |
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\-\-no\-stalls |
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.RS |
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Disable pre-bunch stalls. |
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When specified on the command line, all pre-bunch stall indicators will be |
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ignored. IOs will be replayed without inter-bunch delays. |
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.RE |
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\-v |
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.br |
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\-\-verbose |
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.RS |
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Enable verbose output. |
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When specified on the command line, this option instructs \fIbtreplay\fR |
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to store information concerning each \fBstall\fR and IO operation |
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performed by \fIbtreplay\fR. The name of each file so created will be |
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the input file name used with an extension of \fI.rep\fR appended onto |
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it. Thus, an input file of the name \fIsdab.replay.3\fR would generate a |
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verbose output file with the name \fIsdab.replay.3.rep\fR in the |
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directory specified for input files. |
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.P |
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In addition, \fIbtreplay\fR will also output to \fIstderr\fR the |
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names of the input files being processed. |
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.RE |
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\-V |
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.br |
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\-\-version |
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.RS |
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Show version number and exit. |
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.RE |
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\-W |
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.br |
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\-\-write-enable |
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.RS |
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Enable writing during replay. |
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As a precautionary measure, by default \fIbtreplay\fR will not |
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process \fBwrite\fR requests. In order to enable \fIbtreplay\fR to |
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actually \fBwrite\fR to devices one must explicitly specify the |
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\fI\-W\fR option. |
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.RE |
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.SH AUTHORS |
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\fIbtreplay\fR was written by Alan D. Brunelle. This |
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man page was created from the \fIbtreplay\fR documentation by Bas Zoetekouw. |
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.SH "REPORTING BUGS" |
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Report bugs to <linux\-btrace@vger.kernel.org> |
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.SH COPYRIGHT |
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Copyright \(co 2007 Alan D. Brunelle, Alan D. Brunelle and Nathan Scott. |
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.br |
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This is free software. You may redistribute copies of it under the terms of |
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the GNU General Public License <http://www.gnu.org/licenses/gpl.html>. |
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There is NO WARRANTY, to the extent permitted by law. |
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.br |
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This manual page was created for Debian by Bas Zoetekouw. It was derived from |
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the documentation provided by the authors and it may be used, distributed and |
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modified under the terms of the GNU General Public License, version 2. |
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.br |
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On Debian systems, the text of the GNU General Public License can be found in |
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/usr/share/common\-licenses/GPL\-2. |
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.SH "SEE ALSO" |
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The full documentation for btreplay can be found in /usr/share/doc/blktrace on Debian systems. |
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.br |
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blktrace (8), blkparse (1), btrecord (8) |
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