Local I/O Probes

The strategy probe traces the initiation of local block device I/O by the kernel. It records the device number, logical block number, size, buffer pointer, and buffer flags associated with the transfer. The flag values are the buffer status flags as defined in <sys/buf.h>.

The biodone probe traces the completion of a buffered I/O transfer, that is, calls to the kernel biodone(9f) routine. It records the device number, logical block number, and buffer pointer associated with the transfer.

Physical (raw) I/O is traced by two probes in physio(9f): physio_start and physio_end. These probes record the device number, offset, size, and direction of the I/O transfer.