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 8USE_IONICE(NEWTOY(ionice, "^tc#<0>3=2n#<0>7=5p#", TOYFLAG_USR|TOYFLAG_BIN)) 9USE_IORENICE(NEWTOY(iorenice, "?<1>3", TOYFLAG_USR|TOYFLAG_BIN)) 10 11config 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 27config 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 42GLOBALS( 43 long p, n, c; 44) 45 46static int ioprio_get(void) 47{ 48 return syscall(__NR_ioprio_get, 1, (int)TT.p); 49} 50 51static 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 58void 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 72void 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