LXR toybox/toys/other/taskset.c

   1/* taskset.c - Retrieve or set the CPU affinity of a process.
   2 *
   3 * Copyright 2012 Elie De Brauwer <eliedebrauwer@gmail.com>
   4
   5USE_TASKSET(NEWTOY(taskset, "<1^pa", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_STAYROOT))
   6USE_NPROC(NEWTOY(nproc, "(all)", TOYFLAG_USR|TOYFLAG_BIN))
   7
   8config NPROC
   9  bool "nproc"
  10  default y
  11  help
  12    usage: nproc [--all]
  13
  14    Print number of processors.
  15
  16    --all       Show all processors, not just ones this task can run on
  17
  18config TASKSET
  19  bool "taskset"
  20  default y
  21  help
  22    usage: taskset [-ap] [mask] [PID | cmd [args...]]
  23
  24    Launch a new task which may only run on certain processors, or change
  25    the processor affinity of an existing PID.
  26
  27    Mask is a hex string where each bit represents a processor the process
  28    is allowed to run on. PID without a mask displays existing affinity.
  29
  30    -p  Set/get the affinity of given PID instead of a new command
  31    -a  Set/get the affinity of all threads of the PID
  32*/
  33
  34#define FOR_taskset
  35#include "toys.h"
  36
  37#include <sys/syscall.h>
  38#define sched_setaffinity(pid, size, cpuset) \
  39  syscall(__NR_sched_setaffinity, (pid_t)pid, (size_t)size, (void *)cpuset)
  40#define sched_getaffinity(pid, size, cpuset) \
  41  syscall(__NR_sched_getaffinity, (pid_t)pid, (size_t)size, (void *)cpuset)
  42
  43// mask is an array of long, which makes the layout a bit weird on big
  44// endian systems but as long as it's consistent...
  45
  46static void do_taskset(pid_t pid, int quiet)
  47{
  48  unsigned long *mask = (unsigned long *)toybuf;
  49  char *s = *toys.optargs, *failed = "failed to %s %d's affinity";
  50  int i, j, k;
  51
  52  for (i=0; ; i++) {
  53    if (!quiet) {
  54      int j = sizeof(toybuf), flag = 0;
  55
  56      if (-1 == sched_getaffinity(pid, sizeof(toybuf), (void *)mask))
  57        perror_exit(failed, "get", pid);
  58
  59      printf("pid %d's %s affinity mask: ", pid, i ? "new" : "current");
  60
  61      while (j--) {
  62        int x = 255 & (mask[j/sizeof(long)] >> (8*(j&(sizeof(long)-1))));
  63
  64        if (flag) printf("%02x", x);
  65        else if (x) {
  66          flag++;
  67          printf("%x", x);
  68        }
  69      }
  70      putchar('\n');
  71    }
  72
  73    if (i || toys.optc < 2) return;
  74
  75    memset(toybuf, 0, sizeof(toybuf));
  76    k = strlen(s = *toys.optargs);
  77    s += k;
  78    for (j = 0; j<k; j++) {
  79      unsigned long digit = *(--s) - '0';
  80
  81      if (digit > 9) digit = 10 + tolower(*s)-'a';
  82      if (digit > 15) error_exit("bad mask '%s'", *toys.optargs);
  83      mask[j/(2*sizeof(long))] |= digit << 4*(j&((2*sizeof(long))-1));
  84    }
  85
  86    if (-1 == sched_setaffinity(pid, sizeof(toybuf), (void *)mask))
  87      perror_exit(failed, "set", pid);
  88  }
  89}
  90
  91static int task_callback(struct dirtree *new)
  92{
  93  if (!new->parent) return DIRTREE_RECURSE;
  94  if (isdigit(*new->name)) do_taskset(atoi(new->name), 0);
  95
  96  return 0;
  97}
  98
  99void taskset_main(void)
 100{
 101  if (!(toys.optflags & FLAG_p)) {
 102    if (toys.optc < 2) error_exit("Needs 2 args");
 103    do_taskset(getpid(), 1);
 104    xexec(toys.optargs+1);
 105  } else {
 106    char *c;
 107    pid_t pid = strtol(toys.optargs[toys.optc-1], &c, 10);
 108
 109    if (*c) error_exit("Not int %s", toys.optargs[1]);
 110
 111    if (toys.optflags & FLAG_a) {
 112      char buf[33];
 113      sprintf(buf, "/proc/%ld/task/", (long)pid);
 114      dirtree_read(buf, task_callback);
 115    } else do_taskset(pid, 0);
 116  }
 117}
 118
 119void nproc_main(void)
 120{
 121  unsigned i, j, nproc = 0;
 122
 123  // This can only detect 32768 processors. Call getaffinity and count bits.
 124  if (!toys.optflags && -1!=sched_getaffinity(getpid(), 4096, toybuf)) {
 125    for (i = 0; i<4096; i++)
 126      if (toybuf[i]) for (j=0; j<8; j++) if (toybuf[i]&(1<<j)) nproc++;
 127  }
 128
 129  // If getaffinity failed or --all, count cpu entries in proc
 130  if (!nproc) nproc = sysconf(_SC_NPROCESSORS_CONF);
 131
 132  xprintf("%u\n", nproc);
 133}
 134