Attempt to count the number of bytes which this process really did cause to be fetched from the storage layer. Done at the submit_bio() level, so it is accurate for block-backed filesystems.
The number of bytes which this task has caused to be read from storage. This is simply the sum of bytes which this process passed to read() and pread(), also including tty IO, and it is unaffected by whether or not actual physical disk IO was required.
Attempt to count the number of bytes which this process caused to be sent to the storage layer. This is done at page-dirtying time.
The number of bytes which this task has caused, or shall cause to be written to disk. Similar caveats apply here as with rchar.
Process disk io data filled by glibtop_get_proc_io().