Documentation/block/ioprio.rst

7 -----
12 mq-deadline.
15 ------------------
20 IOPRIO_CLASS_RT: This is the realtime io class. This scheduling class is given
21 higher priority than any other in the system, processes from this class are
23 care, one io RT process can starve the entire system. Within the RT class,
24 there are 8 levels of class data that determine exactly how much time this
29 IOPRIO_CLASS_BE: This is the best-effort scheduling class, which is the default
30 for any process that hasn't set a specific io priority. The class data
36 IOPRIO_CLASS_IDLE: This is the idle scheduling class, processes running at this
37 level only get io time when no one else needs the disk. The idle class has no
38 class data, since it doesn't really apply here.
41 -----
45 	# ionice -c<class> -n<level> -p<pid>
51 	# ionice -c2 -n0 /bin/ls
53 will run ls at the best-effort scheduling class at the highest priority.
56 	# ionice -c1 -n2 -p100
58 will change pid 100 to run at the realtime scheduling class, at priority 2.
111   const char *to_prio[] = { "none", "realtime", "best-effort", "idle", };
145 			printf("bad prio class %d\n", ioprio_class);
155 		printf("pid=%d, %d\n", pid, ioprio);
157 		if (ioprio == -1)
162 			printf("%s: prio %d\n", to_prio[ioprio_class], ioprio);
165 		if (ioprio_set(IOPRIO_WHO_PROCESS, pid, ioprio | ioprio_class << IOPRIO_CLASS_SHIFT) == -1) {