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BTRACE(8)                   System Manager's Manual                  BTRACE(8)

NAME
       btrace - block-level tracing interface

SYNOPSIS
       btrace start device entries

       btrace stop device file

       btrace reset device

       btrace dump file

DESCRIPTION
       The  btrace  tool is the user interface to MINIX3's block-level tracing
       facility. It allows one to start, stop, and reset tracing, and  dump  a
       trace output file in a somewhat human-readable format.

COMMANDS
       start     This  command  starts tracing all block requests on the given
                 device. Each block request takes up one entry in the log. The
                 entries parameter specifies the allocation side of the log in
                 the driver process, in number of (32-byte) entries. Once  the
                 log is full, no more entries will be added.

       stop      This command stops tracing on the given device, and dumps the
                 resulting log to the given output file.

       reset     This command stops tracing on the given device and resets the
                 state  of  the  block  tracer.  This should be useful only in
                 emergency situations.

       dump      Dump the contents of a log file generated earlier with btrace
                 stop,  in  human-readable  format.  Heavy  users of the block
                 tracing facility will probably want to write their own  tools
                 for parsing and visualizing dump files.

LIMITATIONS
       Only one block device can be traced per driver at once. It is therefore
       also not possible to trace a device and all its partitions at the  same
       time.  The tracing facility has been designed for tracing activity of a
       single file system, in which case these limitations are not important.

       The log will always start with a close operation on the  device,  since
       btrace  closes the file descriptor used to instruct the driver to start
       tracing. Similarly, for logs that have not  already  filled  up  during
       tracing, the last entry will be a btrace-triggered open operation.

EXAMPLES
       btrace start /dev/c2d0 10240       # Start a block trace on c2d0.

       btrace stop /dev/c2d0 outfile      # Stop the block trace on c2d0.

       btrace dump outfile                # View the output of the trace.

SEE ALSO
       ioctl(2).

AUTHOR
       David van Moolenbroek <david@minix3.org>

                                                                     BTRACE(8)
NAME | SYNOPSIS | DESCRIPTION | COMMANDS | LIMITATIONS | EXAMPLES | SEE ALSO | AUTHOR