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 source tree.
   7 */
   8
   9//usage:#define taskset_trivial_usage
  10//usage:       "[-p] [MASK] [PID | PROG ARGS]"
  11//usage:#define taskset_full_usage "\n\n"
  12//usage:       "Set or get CPU affinity\n"
  13//usage:     "\n        -p      Operate on an existing PID"
  14//usage:
  15//usage:#define taskset_example_usage
  16//usage:       "$ taskset 0x7 ./dgemm_test&\n"
  17//usage:       "$ taskset -p 0x1 $!\n"
  18//usage:       "pid 4790's current affinity mask: 7\n"
  19//usage:       "pid 4790's new affinity mask: 1\n"
  20//usage:       "$ taskset 0x7 /bin/sh -c './taskset -p 0x1 $$'\n"
  21//usage:       "pid 6671's current affinity mask: 1\n"
  22//usage:       "pid 6671's new affinity mask: 1\n"
  23//usage:       "$ taskset -p 1\n"
  24//usage:       "pid 1's current affinity mask: 3\n"
  25
  26#include <sched.h>
  27#include "libbb.h"
  28
  29#if ENABLE_FEATURE_TASKSET_FANCY
  30#define TASKSET_PRINTF_MASK "%s"
  31/* craft a string from the mask */
  32static char *from_cpuset(cpu_set_t *mask)
  33{
  34        int i;
  35        char *ret = NULL;
  36        char *str = xzalloc((CPU_SETSIZE / 4) + 1); /* we will leak it */
  37
  38        for (i = CPU_SETSIZE - 4; i >= 0; i -= 4) {
  39                int val = 0;
  40                int off;
  41                for (off = 0; off <= 3; ++off)
  42                        if (CPU_ISSET(i + off, mask))
  43                                val |= 1 << off;
  44                if (!ret && val)
  45                        ret = str;
  46                *str++ = bb_hexdigits_upcase[val] | 0x20;
  47        }
  48        return ret;
  49}
  50#else
  51#define TASKSET_PRINTF_MASK "%llx"
  52static unsigned long long from_cpuset(cpu_set_t *mask)
  53{
  54        struct BUG_CPU_SETSIZE_is_too_small {
  55                char BUG_CPU_SETSIZE_is_too_small[
  56                        CPU_SETSIZE < sizeof(int) ? -1 : 1];
  57        };
  58        char *p = (void*)mask;
  59
  60        /* Take the least significant bits. Careful!
  61         * Consider both CPU_SETSIZE=4 and CPU_SETSIZE=1024 cases
  62         */
  63#if BB_BIG_ENDIAN
  64        /* For big endian, it means LAST bits */
  65        if (CPU_SETSIZE < sizeof(long))
  66                p += CPU_SETSIZE - sizeof(int);
  67        else if (CPU_SETSIZE < sizeof(long long))
  68                p += CPU_SETSIZE - sizeof(long);
  69        else
  70                p += CPU_SETSIZE - sizeof(long long);
  71#endif
  72        if (CPU_SETSIZE < sizeof(long))
  73                return *(unsigned*)p;
  74        if (CPU_SETSIZE < sizeof(long long))
  75                return *(unsigned long*)p;
  76        return *(unsigned long long*)p;
  77}
  78#endif
  79
  80
  81int taskset_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  82int taskset_main(int argc UNUSED_PARAM, char **argv)
  83{
  84        cpu_set_t mask;
  85        pid_t pid = 0;
  86        unsigned opt_p;
  87        const char *current_new;
  88        char *pid_str;
  89        char *aff = aff; /* for compiler */
  90
  91        /* NB: we mimic util-linux's taskset: -p does not take
  92         * an argument, i.e., "-pN" is NOT valid, only "-p N"!
  93         * Indeed, util-linux-2.13-pre7 uses:
  94         * getopt_long(argc, argv, "+pchV", ...), not "...p:..." */
  95
  96        opt_complementary = "-1"; /* at least 1 arg */
  97        opt_p = getopt32(argv, "+p");
  98        argv += optind;
  99
 100        if (opt_p) {
 101                pid_str = *argv++;
 102                if (*argv) { /* "-p <aff> <pid> ...rest.is.ignored..." */
 103                        aff = pid_str;
 104                        pid_str = *argv; /* NB: *argv != NULL in this case */
 105                }
 106                /* else it was just "-p <pid>", and *argv == NULL */
 107                pid = xatoul_range(pid_str, 1, ((unsigned)(pid_t)ULONG_MAX) >> 1);
 108        } else {
 109                aff = *argv++; /* <aff> <cmd...> */
 110                if (!*argv)
 111                        bb_show_usage();
 112        }
 113
 114        current_new = "current\0new";
 115        if (opt_p) {
 116 print_aff:
 117                if (sched_getaffinity(pid, sizeof(mask), &mask) < 0)
 118                        bb_perror_msg_and_die("can't %cet pid %d's affinity", 'g', pid);
 119                printf("pid %d's %s affinity mask: "TASKSET_PRINTF_MASK"\n",
 120                                pid, current_new, from_cpuset(&mask));
 121                if (!*argv) {
 122                        /* Either it was just "-p <pid>",
 123                         * or it was "-p <aff> <pid>" and we came here
 124                         * for the second time (see goto below) */
 125                        return EXIT_SUCCESS;
 126                }
 127                *argv = NULL;
 128                current_new += 8; /* "new" */
 129        }
 130
 131        { /* Affinity was specified, translate it into cpu_set_t */
 132                unsigned i;
 133                /* Do not allow zero mask: */
 134                unsigned long long m = xstrtoull_range(aff, 0, 1, ULLONG_MAX);
 135                enum { CNT_BIT = CPU_SETSIZE < sizeof(m)*8 ? CPU_SETSIZE : sizeof(m)*8 };
 136
 137                CPU_ZERO(&mask);
 138                for (i = 0; i < CNT_BIT; i++) {
 139                        unsigned long long bit = (1ULL << i);
 140                        if (bit & m)
 141                                CPU_SET(i, &mask);
 142                }
 143        }
 144
 145        /* Set pid's or our own (pid==0) affinity */
 146        if (sched_setaffinity(pid, sizeof(mask), &mask))
 147                bb_perror_msg_and_die("can't %cet pid %d's affinity", 's', pid);
 148
 149        if (!argv[0]) /* "-p <aff> <pid> [...ignored...]" */
 150                goto print_aff; /* print new affinity and exit */
 151
 152        BB_EXECVP_or_die(argv);
 153}
 154