1 /* ionice.c - set or get process I/O scheduling class and priority
2 *
3 * Copyright 2015 Rob Landley <rob@landley.net>
4 *
5 * It would be really nice if there was a standard, but no. There is
6 * Documentation/block/ioprio.txt in the linux source.
7
8 USE_IONICE(NEWTOY(ionice, "^tc#<0>3=2n#<0>7=5p#", TOYFLAG_USR|TOYFLAG_BIN))
9 USE_IORENICE(NEWTOY(iorenice, "?<1>3", TOYFLAG_USR|TOYFLAG_BIN))
10
11 config IONICE
12 bool "ionice"
13 default y
14 help
15 usage: ionice [-t] [-c CLASS] [-n LEVEL] [COMMAND...|-p PID]
16
17 Change the I/O scheduling priority of a process. With no arguments
18 (or just -p), display process' existing I/O class/priority.
19
20 -c CLASS = 1-3: 1(realtime), 2(best-effort, default), 3(when-idle)
21 -n LEVEL = 0-7: (0 is highest priority, default = 5)
22 -p Affect existing PID instead of spawning new child
23 -t Ignore failure to set I/O priority
24
25 System default iopriority is generally -c 2 -n 4.
26
27 config IORENICE
28 bool "iorenice"
29 default y
30 help
31 usage: iorenice PID [CLASS] [PRIORITY]
32
33 Display or change I/O priority of existing process. CLASS can be
34 "rt" for realtime, "be" for best effort, "idle" for only when idle, or
35 "none" to leave it alone. PRIORITY can be 0-7 (0 is highest, default 4).
36 */
37
38 #define FOR_ionice
39 #include "toys.h"
40 #include <sys/syscall.h>
41
GLOBALS(long p,n,c;)42 GLOBALS(
43 long p, n, c;
44 )
45
46 static int ioprio_get(void)
47 {
48 return syscall(__NR_ioprio_get, 1, (int)TT.p);
49 }
50
ioprio_set(void)51 static int ioprio_set(void)
52 {
53 int prio = ((int)TT.c << 13) | (int)TT.n;
54
55 return syscall(__NR_ioprio_set, 1, (int)TT.p, prio);
56 }
57
ionice_main(void)58 void ionice_main(void)
59 {
60 if (!TT.p && !toys.optc) error_exit("Need -p or COMMAND");
61 if (toys.optflags == FLAG_p) {
62 int p = ioprio_get();
63 xprintf("%s: prio %d\n",
64 (char *[]){"unknown", "Realtime", "Best-effort", "Idle"}[(p>>13)&3],
65 p&7);
66 } else {
67 if (-1 == ioprio_set() && !(toys.optflags&FLAG_t)) perror_exit("set");
68 if (!TT.p) xexec(toys.optargs);
69 }
70 }
71
iorenice_main(void)72 void iorenice_main(void)
73 {
74 char *classes[] = {"none", "rt", "be", "idle"};
75
76 TT.p = atolx(*toys.optargs);
77 if (toys.optc == 1) {
78 int p = ioprio_get();
79
80 if (p == -1) perror_exit("read priority");
81 TT.c = (p>>13)&3;
82 p &= 7;
83 xprintf("Pid %ld, class %s (%ld), prio %d\n", TT.p, classes[TT.c], TT.c, p);
84 return;
85 }
86
87 for (TT.c = 0; TT.c<4; TT.c++)
88 if (!strcmp(toys.optargs[toys.optc-1], classes[TT.c])) break;
89 if (toys.optc == 3 || TT.c == 4) TT.n = atolx(toys.optargs[1]);
90 else TT.n = 4;
91 TT.c &= 3;
92
93 if (-1 == ioprio_set()) perror_exit("set");
94 }
95