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/* chrt.c - Get/set real-time (scheduling) attributes
*
* Copyright 2016 The Android Open Source Project
USE_CHRT(NEWTOY(chrt, "mp#bfiorR[!bfior]", TOYFLAG_USR|TOYFLAG_SBIN))
config CHRT
bool "chrt"
default n
help
usage: chrt [-m] [-p PID] [POLICY PRIO] [COMMAND [ARGS...]]
Get/set a process' real-time (scheduling) attributes.
-p Apply to given pid
-R Set SCHED_RESET_ON_FORK
-m Show min/max priorities available
Policies:
-b SCHED_BATCH -f SCHED_FIFO -i SCHED_IDLE
-o SCHED_OTHER -r SCHED_RR
*/
#define FOR_chrt
#include "toys.h"
#include <linux/sched.h>
GLOBALS(
long pid;
)
static char *policy_name(int policy) {
char *policy_names[] = { "SCHED_OTHER", "SCHED_FIFO", "SCHED_RR",
"SCHED_BATCH", "4", "SCHED_IDLE", "SCHED_DEADLINE" };
return policy < ARRAY_LEN(policy_names) ? policy_names[policy] : "???";
}
void chrt_main(void)
{
int policy = SCHED_RR;
struct sched_param p;
// Show min/maxes?
if (toys.optflags&FLAG_m) {
for (policy = SCHED_OTHER; policy <= SCHED_IDLE; ++policy)
if (policy != 4) // There's an unused hole in the priorities.
printf("%s min/max priority\t: %d/%d\n", policy_name(policy),
sched_get_priority_min(policy), sched_get_priority_max(policy));
return;
}
// If we have a pid but no command or policy, we're just querying.
if (TT.pid && !*(toys.optargs+1) &&
!(toys.optflags&(FLAG_b|FLAG_f|FLAG_i|FLAG_o|FLAG_r))) {
policy = sched_getscheduler(TT.pid);
if (policy == -1) perror_exit("sched_getscheduler");
policy &= ~SCHED_RESET_ON_FORK;
printf("pid %ld's current scheduling policy: %s\n",
TT.pid, policy_name(policy));
if (sched_getparam(TT.pid, &p)) perror_exit("sched_getparam");
printf("pid %ld's current scheduling priority: %d\n",
TT.pid, p.sched_priority);
return;
}
// Did we get a meaningful combination of arguments?
if (!*toys.optargs) help_exit("missing priority");
if (TT.pid && *(toys.optargs+1)) help_exit("-p and command");
if (!TT.pid && !*(toys.optargs+1)) help_exit("missing command");
// Translate into policy and priority.
if (toys.optflags&FLAG_b) policy = SCHED_BATCH;
else if (toys.optflags&FLAG_f) policy = SCHED_FIFO;
else if (toys.optflags&FLAG_i) policy = SCHED_IDLE;
else if (toys.optflags&FLAG_o) policy = SCHED_OTHER;
if (toys.optflags&FLAG_R) policy |= SCHED_RESET_ON_FORK;
p.sched_priority = atolx_range(*toys.optargs, sched_get_priority_min(policy),
sched_get_priority_max(policy));
if (sched_setscheduler(TT.pid, policy, &p)) perror_exit("sched_setscheduler");
if (*(toys.optargs+1)) {
toys.stacktop = 0;
xexec(++toys.optargs);
}
}
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