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/* vi: set sw=4 ts=4:
*
* taskset.c - Retrieve or set the CPU affinity of a process.
*
* Copyright 2012 Elie De Brauwer <eliedebrauwer@gmail.com>
USE_TASKSET(NEWTOY(taskset, "<1^pa", TOYFLAG_BIN|TOYFLAG_STAYROOT))
config TASKSET
bool "taskset"
default y
help
usage: taskset [-ap] [mask] [PID | cmd [args...]]
Launch a new task which may only run on certain processors, or change
the processor affinity of an exisitng PID.
Mask is a hex string where each bit represents a processor the process
is allowed to run on. PID without a mask displays existing affinity.
-p Set/get the affinity of given PID instead of a new command.
-a Set/get the affinity of all threads of the PID.
*/
#include "toys.h"
#define FLAG_a 0x1
#define FLAG_p 0x2
// Prototype for syscall wrappers sched.h refuses to give us
int sched_setaffinity(pid_t pid, size_t size, void *cpuset);
int sched_getaffinity(pid_t pid, size_t size, void *cpuset);
// mask is an array of long, which makes the layout a bit weird on big
// endian systems but as long as it's consistent...
static void do_taskset(pid_t pid, int quiet)
{
unsigned long *mask = (unsigned long *)toybuf;
char *s = *toys.optargs, *failed = "failed to %s %d's affinity";
int i, j, k;
for (i=0; ; i++) {
if (!quiet) {
int j = sizeof(toybuf), flag = 0;
if (sched_getaffinity(pid, sizeof(toybuf), (void *)mask))
perror_exit(failed, "get", pid);
printf("pid %d's %s affinity mask: ", pid, i ? "new" : "current");
while (j--) {
int x = 255 & (mask[j/sizeof(long)] >> (8*(j&(sizeof(long)-1))));
if (flag) printf("%02x", x);
else if (x) {
flag++;
printf("%x", x);
}
}
putchar('\n');
}
if (i || toys.optc < 2) return;
memset(toybuf, 0, sizeof(toybuf));
k = strlen(s = *toys.optargs);
s += k;
for (j = 0; j<k; j++) {
unsigned long digit = *(--s) - '0';
if (digit > 9) digit = 10 + tolower(*s)-'a';
if (digit > 15) error_exit("bad mask '%s'", *toys.optargs);
mask[j/(2*sizeof(long))] |= digit << 4*(j&((2*sizeof(long))-1));
}
if (sched_setaffinity(pid, sizeof(toybuf), (void *)mask))
perror_exit(failed, "set", pid);
}
}
static int task_callback(struct dirtree *new)
{
if (!new->parent) return DIRTREE_RECURSE;
if (isdigit(*new->name)) do_taskset(atoi(new->name), 0);
return 0;
}
void taskset_main(void)
{
if (!(toys.optflags & FLAG_p)) {
if (toys.optc < 2) error_exit("Needs 2 args");
do_taskset(getpid(), 1);
xexec(toys.optargs+1);
} else {
char *c;
pid_t pid = strtol(toys.optargs[toys.optc-1], &c, 10);
if (*c) error_exit("Not int %s", toys.optargs[1]);
if (toys.optflags & FLAG_a) {
char buf[33];
sprintf(buf, "/proc/%ld/task/", (long)pid);
dirtree_read(buf, task_callback);
} else do_taskset(pid, 0);
}
}
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