Iotop-c does for I/O usage what top(1) does for CPU usage. It watches I/O usage information output by the Linux kernel and displays a table of current I/O usage by processes on the system. It is handy for answering the question "Why is the disk churning so much?".

iotop-c requires a Linux kernel built with the CONFIG_TASKSTATS, CONFIG_TASK_DELAY_ACCT, CONFIG_TASK_IO_ACCOUNTING and CONFIG_VM_EVENT_COUNTERS config options on.

iotop-c is an alternative re-implementation of iotop in C, optimized for performance. Normally a monitoring tool intended to be used on a system under heavy stress should use the least additional resources as possible.