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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.
#include <sys/syscall.h>
#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
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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