1 /* chrt.c - Get/set real-time (scheduling) attributes 2 * 3 * Copyright 2016 The Android Open Source Project 4 * 5 * Note: -ibrfo flags sorted to match SCHED positions for highest_bit() 6 7 USE_CHRT(NEWTOY(chrt, "^mp#<0iRbrfo[!ibrfo]", TOYFLAG_USR|TOYFLAG_SBIN)) 8 9 config CHRT 10 bool "chrt" 11 default y 12 help 13 usage: chrt [-Rmofrbi] {-p PID [PRIORITY] | [PRIORITY COMMAND...]} 14 15 Get/set a process' real-time scheduling policy and priority. 16 17 -p Set/query given pid (instead of running COMMAND) 18 -R Set SCHED_RESET_ON_FORK 19 -m Show min/max priorities available 20 21 Set policy (default -r): 22 23 -o SCHED_OTHER -f SCHED_FIFO -r SCHED_RR 24 -b SCHED_BATCH -i SCHED_IDLE 25 */ 26 27 #define FOR_chrt 28 #include "toys.h" 29 30 GLOBALS( 31 long pid; 32 ) 33 34 #ifndef _POSIX_PRIORITY_SCHEDULING 35 #warning "musl-libc intentionally broke sched_get_priority_min() and friends in commit 1e21e78bf7a5 because its maintainer didn't like those Linux system calls" 36 #endif 37 38 char *polnames[] = { 39 "SCHED_OTHER", "SCHED_FIFO", "SCHED_RR", "SCHED_BATCH", 0, "SCHED_IDLE", 40 "SCHED_DEADLINE" 41 }; 42 43 void chrt_main(void) 44 { 45 int pol, pri; 46 47 // Show min/maxes? 48 if (toys.optflags&FLAG_m) { 49 for (pol = 0; pol<ARRAY_LEN(polnames); pol++) if (polnames[pol]) 50 printf("%s min/max priority\t: %d/%d\n", polnames[pol], 51 sched_get_priority_min(pol), sched_get_priority_max(pol)); 52 53 return; 54 } 55 56 // Query when -p without priority. 57 if (toys.optflags==FLAG_p && !*toys.optargs) { 58 char *s = "???", *R = ""; 59 60 if (-1==(pol = sched_getscheduler(TT.pid))) perror_exit("pid %ld", TT.pid); 61 if (pol & SCHED_RESET_ON_FORK) R = "|SCHED_RESET_ON_FORK"; 62 if ((pol &= ~SCHED_RESET_ON_FORK)<ARRAY_LEN(polnames)) s = polnames[pol]; 63 printf("pid %ld's current scheduling policy: %s%s\n", TT.pid, s, R); 64 65 if (sched_getparam(TT.pid, (void *)&pri)) perror_exit("sched_getparam"); 66 printf("pid %ld's current scheduling priority: %d\n", TT.pid, pri); 67 68 return; 69 } 70 71 if (!*toys.optargs) help_exit("no PRIORITY"); 72 if (!toys.optargs[1] == !(toys.optflags&FLAG_p)) 73 help_exit("need 1 of -p or COMMAND"); 74 75 // Set policy and priority 76 if (-1==(pol = highest_bit(toys.optflags&0x2f))) pol = SCHED_RR; 77 pri = atolx_range(*toys.optargs, sched_get_priority_min(pol), 78 sched_get_priority_max(pol)); 79 if (toys.optflags&FLAG_R) pol |= SCHED_RESET_ON_FORK; 80 81 if (sched_setscheduler(TT.pid, pol, (void *)&pri)) 82 perror_exit("sched_setscheduler"); 83 84 if (*(toys.optargs+1)) xexec(toys.optargs+1); 85 } 86
