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 7USE_CHRT(NEWTOY(chrt, "^mp#<0iRbrfo[!ibrfo]", TOYFLAG_USR|TOYFLAG_BIN)) 8 9config 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 30GLOBALS( 31 long p; 32) 33 34#ifndef _POSIX_PRIORITY_SCHEDULING 35// musl-libc intentionally broke sched_get_priority_min() and friends in 36// commit 1e21e78bf7a5 because its maintainer didn't like those Linux 37// system calls, so work around it here. 38#include <sys/syscall.h> 39#define sched_get_priority_min(policy) \ 40 (int)syscall(SYS_sched_get_priority_min, (int)policy) 41#define sched_get_priority_max(policy) \ 42 (int)syscall(SYS_sched_get_priority_max, (int)policy) 43#define sched_getparam(pid, param) \ 44 syscall(SYS_sched_getparam, (pid_t)pid, (void *)param) 45#define sched_getscheduler(pid) \ 46 syscall(SYS_sched_getscheduler, (pid_t)pid) 47#define sched_setscheduler(pid, scheduler, param) \ 48 syscall(SYS_sched_setscheduler, (pid_t)pid, (int)scheduler, (void *)param) 49#endif 50 51char *polnames[] = { 52 "SCHED_OTHER", "SCHED_FIFO", "SCHED_RR", "SCHED_BATCH", 0, "SCHED_IDLE", 53 "SCHED_DEADLINE" 54}; 55 56void chrt_main(void) 57{ 58 int pol, pri; 59 60 // Show min/maxes? 61 if (toys.optflags&FLAG_m) { 62 for (pol = 0; pol<ARRAY_LEN(polnames); pol++) if (polnames[pol]) 63 printf("%s min/max priority\t: %d/%d\n", polnames[pol], 64 sched_get_priority_min(pol), sched_get_priority_max(pol)); 65 66 return; 67 } 68 69 // Query when -p without priority. 70 if (toys.optflags==FLAG_p && !*toys.optargs) { 71 char *s = "???", *R = ""; 72 73 if (-1==(pol = sched_getscheduler(TT.p))) perror_exit("pid %ld", TT.p); 74 if (pol & SCHED_RESET_ON_FORK) R = "|SCHED_RESET_ON_FORK"; 75 if ((pol &= ~SCHED_RESET_ON_FORK)<ARRAY_LEN(polnames)) s = polnames[pol]; 76 printf("pid %ld's current scheduling policy: %s%s\n", TT.p, s, R); 77 78 if (sched_getparam(TT.p, (void *)&pri)) perror_exit("sched_getparam"); 79 printf("pid %ld's current scheduling priority: %d\n", TT.p, pri); 80 81 return; 82 } 83 84 if (!*toys.optargs) help_exit("no PRIORITY"); 85 if (!toys.optargs[1] == !(toys.optflags&FLAG_p)) 86 help_exit("need 1 of -p or COMMAND"); 87 88 // Set policy and priority 89 if (-1==(pol = highest_bit(toys.optflags&0x2f))) pol = SCHED_RR; 90 pri = atolx_range(*toys.optargs, sched_get_priority_min(pol), 91 sched_get_priority_max(pol)); 92 if (toys.optflags&FLAG_R) pol |= SCHED_RESET_ON_FORK; 93 94 if (sched_setscheduler(TT.p, pol, (void *)&pri)) 95 perror_exit("sched_setscheduler"); 96 97 if (*(toys.optargs+1)) xexec(toys.optargs+1); 98} 99