LXR busybox/miscutils/taskset.c

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * taskset - retrieve or set a processes' CPU affinity
   4 * Copyright (c) 2006 Bernhard Reutner-Fischer
   5 *
   6 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
   7 */
   8
   9#include <sched.h>
  10#include "libbb.h"
  11
  12#if ENABLE_FEATURE_TASKSET_FANCY
  13#define TASKSET_PRINTF_MASK "%s"
  14/* craft a string from the mask */
  15static char *from_cpuset(cpu_set_t *mask)
  16{
  17        int i;
  18        char *ret = NULL;
  19        char *str = xzalloc((CPU_SETSIZE / 4) + 1); /* we will leak it */
  20
  21        for (i = CPU_SETSIZE - 4; i >= 0; i -= 4) {
  22                int val = 0;
  23                int off;
  24                for (off = 0; off <= 3; ++off)
  25                        if (CPU_ISSET(i + off, mask))
  26                                val |= 1 << off;
  27                if (!ret && val)
  28                        ret = str;
  29                *str++ = bb_hexdigits_upcase[val] | 0x20;
  30        }
  31        return ret;
  32}
  33#else
  34#define TASKSET_PRINTF_MASK "%llx"
  35static unsigned long long from_cpuset(cpu_set_t *mask)
  36{
  37        struct BUG_CPU_SETSIZE_is_too_small {
  38                char BUG_CPU_SETSIZE_is_too_small[
  39                        CPU_SETSIZE < sizeof(int) ? -1 : 1];
  40        };
  41        char *p = (void*)mask;
  42
  43        /* Take the least significant bits. Careful!
  44         * Consider both CPU_SETSIZE=4 and CPU_SETSIZE=1024 cases
  45         */
  46#if BB_BIG_ENDIAN
  47        /* For big endian, it means LAST bits */
  48        if (CPU_SETSIZE < sizeof(long))
  49                p += CPU_SETSIZE - sizeof(int);
  50        else if (CPU_SETSIZE < sizeof(long long))
  51                p += CPU_SETSIZE - sizeof(long);
  52        else
  53                p += CPU_SETSIZE - sizeof(long long);
  54#endif
  55        if (CPU_SETSIZE < sizeof(long))
  56                return *(unsigned*)p;
  57        if (CPU_SETSIZE < sizeof(long long))
  58                return *(unsigned long*)p;
  59        return *(unsigned long long*)p;
  60}
  61#endif
  62
  63
  64int taskset_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  65int taskset_main(int argc UNUSED_PARAM, char **argv)
  66{
  67        cpu_set_t mask;
  68        pid_t pid = 0;
  69        unsigned opt_p;
  70        const char *current_new;
  71        char *pid_str;
  72        char *aff = aff; /* for compiler */
  73
  74        /* NB: we mimic util-linux's taskset: -p does not take
  75         * an argument, i.e., "-pN" is NOT valid, only "-p N"!
  76         * Indeed, util-linux-2.13-pre7 uses:
  77         * getopt_long(argc, argv, "+pchV", ...), not "...p:..." */
  78
  79        opt_complementary = "-1"; /* at least 1 arg */
  80        opt_p = getopt32(argv, "+p");
  81        argv += optind;
  82
  83        if (opt_p) {
  84                pid_str = *argv++;
  85                if (*argv) { /* "-p <aff> <pid> ...rest.is.ignored..." */
  86                        aff = pid_str;
  87                        pid_str = *argv; /* NB: *argv != NULL in this case */
  88                }
  89                /* else it was just "-p <pid>", and *argv == NULL */
  90                pid = xatoul_range(pid_str, 1, ((unsigned)(pid_t)ULONG_MAX) >> 1);
  91        } else {
  92                aff = *argv++; /* <aff> <cmd...> */
  93                if (!*argv)
  94                        bb_show_usage();
  95        }
  96
  97        current_new = "current\0new";
  98        if (opt_p) {
  99 print_aff:
 100                if (sched_getaffinity(pid, sizeof(mask), &mask) < 0)
 101                        bb_perror_msg_and_die("can't %cet pid %d's affinity", 'g', pid);
 102                printf("pid %d's %s affinity mask: "TASKSET_PRINTF_MASK"\n",
 103                                pid, current_new, from_cpuset(&mask));
 104                if (!*argv) {
 105                        /* Either it was just "-p <pid>",
 106                         * or it was "-p <aff> <pid>" and we came here
 107                         * for the second time (see goto below) */
 108                        return EXIT_SUCCESS;
 109                }
 110                *argv = NULL;
 111                current_new += 8; /* "new" */
 112        }
 113
 114        { /* Affinity was specified, translate it into cpu_set_t */
 115                unsigned i;
 116                /* Do not allow zero mask: */
 117                unsigned long long m = xstrtoull_range(aff, 0, 1, ULLONG_MAX);
 118                enum { CNT_BIT = CPU_SETSIZE < sizeof(m)*8 ? CPU_SETSIZE : sizeof(m)*8 };
 119
 120                CPU_ZERO(&mask);
 121                for (i = 0; i < CNT_BIT; i++) {
 122                        unsigned long long bit = (1ULL << i);
 123                        if (bit & m)
 124                                CPU_SET(i, &mask);
 125                }
 126        }
 127
 128        /* Set pid's or our own (pid==0) affinity */
 129        if (sched_setaffinity(pid, sizeof(mask), &mask))
 130                bb_perror_msg_and_die("can't %cet pid %d's affinity", 's', pid);
 131
 132        if (!argv[0]) /* "-p <aff> <pid> [...ignored...]" */
 133                goto print_aff; /* print new affinity and exit */
 134
 135        BB_EXECVP_or_die(argv);
 136}
 137