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- /* chrt.c - Get/set real-time (scheduling) attributes
- *
- * Copyright 2016 The Android Open Source Project
- *
- * Note: -ibrfo flags sorted to match SCHED positions for highest_bit()
- USE_CHRT(NEWTOY(chrt, "^mp#<0iRbrfo[!ibrfo]", TOYFLAG_USR|TOYFLAG_BIN))
- config CHRT
- bool "chrt"
- default y
- help
- usage: chrt [-Rmofrbi] {-p PID [PRIORITY] | [PRIORITY COMMAND...]}
- Get/set a process' real-time scheduling policy and priority.
- -p Set/query given pid (instead of running COMMAND)
- -R Set SCHED_RESET_ON_FORK
- -m Show min/max priorities available
- Set policy (default -r):
- -o SCHED_OTHER -f SCHED_FIFO -r SCHED_RR
- -b SCHED_BATCH -i SCHED_IDLE
- */
- #define FOR_chrt
- #include "toys.h"
- GLOBALS(
- long p;
- )
- #ifndef _POSIX_PRIORITY_SCHEDULING
- // musl-libc intentionally broke sched_get_priority_min() and friends in
- // commit 1e21e78bf7a5 because its maintainer didn't like those Linux
- // system calls, so work around it here.
- #define sched_get_priority_min(policy) \
- (int)syscall(SYS_sched_get_priority_min, (int)policy)
- #define sched_get_priority_max(policy) \
- (int)syscall(SYS_sched_get_priority_max, (int)policy)
- #define sched_getparam(pid, param) \
- syscall(SYS_sched_getparam, (pid_t)pid, (void *)param)
- #define sched_getscheduler(pid) \
- syscall(SYS_sched_getscheduler, (pid_t)pid)
- #define sched_setscheduler(pid, scheduler, param) \
- syscall(SYS_sched_setscheduler, (pid_t)pid, (int)scheduler, (void *)param)
- #endif
- static char *polnames[] = {
- "SCHED_OTHER", "SCHED_FIFO", "SCHED_RR", "SCHED_BATCH", 0, "SCHED_IDLE",
- "SCHED_DEADLINE"
- };
- void chrt_main(void)
- {
- int pol, pri;
- // Show min/maxes?
- if (toys.optflags&FLAG_m) {
- for (pol = 0; pol<ARRAY_LEN(polnames); pol++) if (polnames[pol])
- printf("%s min/max priority\t: %d/%d\n", polnames[pol],
- sched_get_priority_min(pol), sched_get_priority_max(pol));
- return;
- }
- // Query when -p without priority.
- if (toys.optflags==FLAG_p && !*toys.optargs) {
- char *s = "???", *R = "";
- if (-1==(pol = sched_getscheduler(TT.p))) perror_exit("pid %ld", TT.p);
- if (pol & SCHED_RESET_ON_FORK) R = "|SCHED_RESET_ON_FORK";
- if ((pol &= ~SCHED_RESET_ON_FORK)<ARRAY_LEN(polnames)) s = polnames[pol];
- printf("pid %ld's current scheduling policy: %s%s\n", TT.p, s, R);
- if (sched_getparam(TT.p, (void *)&pri)) perror_exit("sched_getparam");
- printf("pid %ld's current scheduling priority: %d\n", TT.p, pri);
- return;
- }
- if (!*toys.optargs) help_exit("no PRIORITY");
- if (!toys.optargs[1] == !(toys.optflags&FLAG_p))
- help_exit("need 1 of -p or COMMAND");
- // Set policy and priority
- if (-1==(pol = highest_bit(toys.optflags&0x2f))) pol = SCHED_RR;
- pri = atolx_range(*toys.optargs, sched_get_priority_min(pol),
- sched_get_priority_max(pol));
- if (toys.optflags&FLAG_R) pol |= SCHED_RESET_ON_FORK;
- if (sched_setscheduler(TT.p, pol, (void *)&pri))
- perror_exit("sched_setscheduler");
- if (*(toys.optargs+1)) xexec(toys.optargs+1);
- }
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