awionice

awionice is a command-line utility for configuring the I/O scheduling priority of processes on Linux and similar Unix-like systems. It provides a wrapper-style interface for assigning I/O priority to a running process or to a command that is started under the tool, in a manner similar to the more common ionice utility. By setting the I/O class and priority, awionice aims to influence how the kernel schedules disk I/O among competing tasks.

Typical usage includes applying priority to an existing process or launching a new command with a specified I/O priority. For a running process, a common form is awionice -c CLASS -n LEVEL -p PID. To start a command with a given priority, you might use awionice -c CLASS -n LEVEL command [args]. The -c option selects the I/O class (for example, 1 = realtime, 2 = best-effort, 3 = idle) and -n sets the priority level within that class (usually 0–7, with 0 being the highest priority). The -p option targets an existing process by PID.

The effectiveness of awionice depends on the kernel’s I/O scheduling subsystem and the active IO scheduler (such as CFQ or BFQ) as well as hardware characteristics. It typically requires appropriate privileges (often root) to alter a process’s I/O priority. Some distributions provide awionice as part of their I/O scheduling tools, while others offer ionice as the primary interface for controlling IO priority.

See also: ionice, I/O scheduler, CFQ, BFQ, at, batch.