dtrace_io — a DTrace provider for tracing events related to disk I/O

       The  fields of structbio are described in the g_bio(9) manual page, and the fields of structdevstat are
       described in the devstat(9) manual page.  Translators for the bufinfo_t and devinfo_t D types are defined
       in /usr/lib/dtrace/io.d.

       This manual page was written by Mark Johnston <markj@FreeBSD.org>.

       The io:::wait-start() and io:::wait-done() probes are not currently implemented on FreeBSD.

Debian                                           April 18, 2015                                     DTRACE_IO(4)

       This provider is not compatible with the io provider found in Solaris, as its probes use  native  FreeBSD
       argument types.

       The  io  provider allows the tracing of disk I/O events.  The io:::start() probe fires when a I/O request
       is about to be sent to  the  backing  driver  of  a  disk(9)  object.   This  occurs  after  all  GEOM(4)
       transformations  have  been  performed on the request.  The io:::done() probe fires when a I/O request is
       completed.  Both probes take a structbio* representing the I/O request as their  first  argument.   The
       second argument is a structdevstat* for the underlying disk(9) object.

       The following script shows a per-process breakdown of total I/O by disk device:

             #pragma D option quiet

             io:::start
             {
                     @[args[1]->device_name, execname, pid] = sum(args[0]->bio_bcount);
             }

             END
             {
                     printf("%10s %20s %10s %15s\n", "DEVICE", "APP", "PID", "BYTES");
                     printa("%10s %20s %10d %15@d\n", @);
             }

/usr/lib/dtrace/io.d  DTrace type and translator definitions for the io provider.

       The io provider first appeared in FreeBSD 9.2 and 10.0.

       dtrace_io — a DTrace provider for tracing events related to disk I/O

dtrace(1), devstat(9), SDT(9)

io:::start(structbio*, structdevstat*);

       io:::done(structbio*, structdevstat*);