io
Probes
The io
probes are the following:
-
start
-
Fires when an I/O request is about to be made either to a peripheral device or to an NFS server. The
bufinfo_t
corresponding to the I/O request is pointed to byargs[0]
. Thedevinfo_t
of the device to which the I/O is being issued is pointed to byargs[1]
. Thefileinfo_t
of the file that corresponds to the I/O request is pointed to byargs[2]
. Note that file information availability depends on the filesystem making the I/O request. Seefileinfo_t
for more information. -
done
-
Fires after an I/O request has been fulfilled. The
bufinfo_t
corresponding to the I/O request is pointed to byargs[0]
. Thedone
probe fires after the I/O completes, but before completion processing has been performed on the buffer. As a resultB_DONE
is not set inb_flags
at the time thedone
probe fires. Thedevinfo_t
of the device to which the I/O was issued is pointed to byargs[1]
. Thefileinfo_t
of the file that corresponds to the I/O request is pointed to byargs[2]
. -
wait-start
-
Fires immediately before a thread begins to wait pending completion of a given I/O request. The
bufinfo_t
structure corresponding to the I/O request for which the thread will wait is pointed to byargs[0]
. Thedevinfo_t
of the device to which the I/O was issued is pointed to byargs[1]
. Thefileinfo_t
of the file that corresponds to the I/O request is pointed to byargs[2]
. Some time after the wait-start probe fires, the wait-done probe will fire in the same thread. -
wait-done
-
Fires when a thread is done waiting for the completion of a given I/O request. The
bufinfo_t
corresponding to the I/O request for which the thread will wait is pointed to byargs[0]
. Thedevinfo_t
of the device to which the I/O was issued is pointed to byargs[1]
. Thefileinfo_t
of the file that corresponds to the I/O request is pointed to byargs[2]
. Thewait-done
probe fires only after thewait-start
probe has fired in the same thread.
Note that the io
probes fire for all I/O requests
to peripheral devices, and for all file read and file write requests
to an NFS server. Requests for metadata from an NFS server, for
example, do not trigger io
probes due to a
readdir
() request.