LXR busybox/util-linux/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//config:config TASKSET
   9//config:       bool "taskset (4.2 kb)"
  10//config:       default y
  11//config:       help
  12//config:       Retrieve or set a processes's CPU affinity.
  13//config:       This requires sched_{g,s}etaffinity support in your libc.
  14//config:
  15//config:config FEATURE_TASKSET_FANCY
  16//config:       bool "Fancy output"
  17//config:       default y
  18//config:       depends on TASKSET
  19//config:       help
  20//config:       Needed for machines with more than 32-64 CPUs:
  21//config:       affinity parameter 0xHHHHHHHHHHHHHHHHHHHH can be arbitrarily long
  22//config:       in this case. Otherwise, it is limited to sizeof(long).
  23//config:
  24//config:config FEATURE_TASKSET_CPULIST
  25//config:       bool "CPU list support (-c option)"
  26//config:       default y
  27//config:       depends on FEATURE_TASKSET_FANCY
  28//config:       help
  29//config:       Add support for taking/printing affinity as CPU list when '-c'
  30//config:       option is used. For example, it prints '0-3,7' instead of mask '8f'.
  31
  32//applet:IF_TASKSET(APPLET_NOEXEC(taskset, taskset, BB_DIR_USR_BIN, BB_SUID_DROP, taskset))
  33
  34//kbuild:lib-$(CONFIG_TASKSET) += taskset.o
  35
  36//usage:#define taskset_trivial_usage
  37//usage:       "[-ap] [HEXMASK"IF_FEATURE_TASKSET_CPULIST(" | -c LIST")"] { PID | PROG ARGS }"
  38//usage:#define taskset_full_usage "\n\n"
  39//usage:       "Set or get CPU affinity\n"
  40//usage:     "\n        -p      Operate on PID"
  41//usage:     "\n        -a      Operate on all threads"
  42//usage:     "\n        -c      Affinity is a list, not mask"
  43//usage:
  44//usage:#define taskset_example_usage
  45//usage:       "$ taskset 0x7 ./dgemm_test&\n"
  46//usage:       "$ taskset -p 0x1 $!\n"
  47//usage:       "pid 4790's current affinity mask: 7\n"
  48//usage:       "pid 4790's new affinity mask: 1\n"
  49//usage:       "$ taskset 0x7 /bin/sh -c './taskset -p 0x1 $$'\n"
  50//usage:       "pid 6671's current affinity mask: 1\n"
  51//usage:       "pid 6671's new affinity mask: 1\n"
  52//usage:       "$ taskset -p 1\n"
  53//usage:       "pid 1's current affinity mask: 3\n"
  54/*
  55 * Not yet implemented:
  56 * -a/--all-tasks (affect all threads)
  57 *      needs to get TIDs from /proc/PID/task/ and use _them_ as "pid" in sched_setaffinity(pid)
  58 */
  59
  60#include <sched.h>
  61#include "libbb.h"
  62
  63typedef unsigned long ul;
  64#define SZOF_UL (unsigned)(sizeof(ul))
  65#define BITS_UL (unsigned)(sizeof(ul)*8)
  66#define MASK_UL (unsigned)(sizeof(ul)*8 - 1)
  67
  68#if ENABLE_FEATURE_TASKSET_FANCY
  69#define TASKSET_PRINTF_MASK "%s"
  70/* craft a string from the mask */
  71static char *from_mask(const ul *mask, unsigned sz_in_bytes)
  72{
  73        char *str = xzalloc((sz_in_bytes+1) * 2); /* we will leak it */
  74        char *p = str;
  75        for (;;) {
  76                ul v = *mask++;
  77                if (SZOF_UL == 4)
  78                        p += sprintf(p, "%08lx", v);
  79                if (SZOF_UL == 8)
  80                        p += sprintf(p, "%016lx", v);
  81                if (SZOF_UL == 16)
  82                        p += sprintf(p, "%032lx", v); /* :) */
  83                sz_in_bytes -= SZOF_UL;
  84                if ((int)sz_in_bytes <= 0)
  85                        break;
  86        }
  87        while (str[0] == '0' && str[1])
  88                str++;
  89        return str;
  90}
  91#else
  92#define TASKSET_PRINTF_MASK "%lx"
  93static unsigned long from_mask(ul *mask, unsigned sz_in_bytes UNUSED_PARAM)
  94{
  95        return *mask;
  96}
  97#endif
  98
  99static unsigned long *get_aff(int pid, unsigned *sz)
 100{
 101        int r;
 102        unsigned long *mask = NULL;
 103        unsigned sz_in_bytes = *sz;
 104
 105        for (;;) {
 106                mask = xrealloc(mask, sz_in_bytes);
 107                r = sched_getaffinity(pid, sz_in_bytes, (void*)mask);
 108                if (r == 0)
 109                        break;
 110                sz_in_bytes *= 2;
 111                if (errno == EINVAL && (int)sz_in_bytes > 0)
 112                        continue;
 113                bb_perror_msg_and_die("can't %cet pid %d's affinity", 'g', pid);
 114        }
 115        //bb_error_msg("get mask[0]:%lx sz_in_bytes:%d", mask[0], sz_in_bytes);
 116        *sz = sz_in_bytes;
 117        return mask;
 118}
 119
 120#if ENABLE_FEATURE_TASKSET_CPULIST
 121/*
 122 * Parse the CPU list and set the mask accordingly.
 123 *
 124 * The list element can be either a CPU index or a range of CPU indices.
 125 * Example: "1,3,5-7". Stride can be specified: "0-7:2" is "0,2,4,6".
 126 * Note: leading and trailing whitespace is not allowed.
 127 *  util-linux 2.31 allows leading and sometimes trailing whitespace:
 128 *  ok:     taskset -c ' 1,  2'
 129 *  ok:     taskset -c ' 1 , 2'
 130 *  ok:     taskset -c ' 1-7: 2 ,8'
 131 *  not ok: taskset -c ' 1 '
 132 *  not ok: taskset -c ' 1-7: 2 '
 133 */
 134static void parse_cpulist(ul *mask, unsigned max, char *s)
 135{
 136        char *aff = s;
 137        for (;;) {
 138                unsigned bit, end;
 139                unsigned stride = 1;
 140
 141                bit = end = bb_strtou(s, &s, 10);
 142                if (*s == '-') {
 143                        s++;
 144                        end = bb_strtou(s, &s, 10);
 145                        if (*s == ':') {
 146                                s++;
 147                                stride = bb_strtou(s, &s, 10);
 148                        }
 149                }
 150                if ((*s != ',' && *s != '\0')
 151                 || bit > end
 152                 || end == UINT_MAX /* bb_strtou returns this on malformed / ERANGE numbers */
 153                 || (stride - 1) > (UINT_MAX / 4)
 154                /* disallow 0, malformed input, and too large stride prone to overflows */
 155                ) {
 156                        bb_error_msg_and_die("bad affinity '%s'", aff);
 157                }
 158                while (bit <= end && bit < max) {
 159                        mask[bit / BITS_UL] |= (1UL << (bit & MASK_UL));
 160                        bit += stride;
 161                }
 162                if (*s == '\0')
 163                        break;
 164                s++;
 165        }
 166}
 167static void print_cpulist(const ul *mask, unsigned mask_size_in_bytes)
 168{
 169        const ul *mask_end;
 170        const char *delim;
 171        unsigned pos;
 172        ul bit;
 173
 174        mask_end = mask + mask_size_in_bytes / sizeof(mask[0]);
 175        delim = "";
 176        pos = 0;
 177        bit = 1;
 178        for (;;) {
 179                if (*mask & bit) {
 180                        unsigned onebit = pos + 1;
 181                        printf("%s%u", delim, pos);
 182                        do {
 183                                pos++;
 184                                bit <<= 1;
 185                                if (bit == 0) {
 186                                        mask++;
 187                                        if (mask >= mask_end)
 188                                                break;
 189                                        bit = 1;
 190                                }
 191                        } while (*mask & bit);
 192                        if (onebit != pos)
 193                                printf("-%u", pos - 1);
 194                        delim = ",";
 195                }
 196                pos++;
 197                bit <<= 1;
 198                if (bit == 0) {
 199                        mask++;
 200                        if (mask >= mask_end)
 201                                break;
 202                        bit = 1;
 203                }
 204        }
 205        bb_putchar('\n');
 206}
 207#endif
 208
 209enum {
 210        OPT_p = 1 << 0,
 211        OPT_a = 1 << 1,
 212        OPT_c = (1 << 2) * ENABLE_FEATURE_TASKSET_CPULIST,
 213};
 214
 215static int process_pid_str(const char *pid_str, unsigned opts, char *aff)
 216{
 217        ul *mask;
 218        unsigned mask_size_in_bytes;
 219        const char *current_new;
 220        pid_t pid = !pid_str ? 0 : xatou_range(pid_str, 1, INT_MAX); /* disallow "0": "taskset -p 0" should fail */
 221
 222        mask_size_in_bytes = SZOF_UL;
 223        current_new = "current";
 224 print_aff:
 225        mask = get_aff(pid, &mask_size_in_bytes);
 226        if (opts & OPT_p) {
 227#if ENABLE_FEATURE_TASKSET_CPULIST
 228                if (opts & OPT_c) {
 229                        printf("pid %d's %s affinity list: ", pid, current_new);
 230                        print_cpulist(mask, mask_size_in_bytes);
 231                } else
 232#endif
 233                        printf("pid %d's %s affinity mask: "TASKSET_PRINTF_MASK"\n",
 234                                pid, current_new, from_mask(mask, mask_size_in_bytes));
 235                if (!aff) {
 236                        /* Either it was just "-p <pid>",
 237                         * or it was "-p <aff> <pid>" and we came here
 238                         * for the second time (see goto below) */
 239                        return 0;
 240                }
 241                current_new = "new";
 242        }
 243        memset(mask, 0, mask_size_in_bytes);
 244
 245        if (!ENABLE_FEATURE_TASKSET_FANCY) {
 246                /* Affinity was specified, translate it into mask */
 247                /* it is always in hex, skip "0x" if it exists */
 248                if (aff[0] == '0' && (aff[1]|0x20) == 'x')
 249                        aff += 2;
 250                mask[0] = xstrtoul(aff, 16);
 251        }
 252#if ENABLE_FEATURE_TASKSET_CPULIST
 253        else if (opts & OPT_c) {
 254                parse_cpulist(mask, mask_size_in_bytes * 8, aff);
 255        }
 256#endif
 257        else {
 258                unsigned i;
 259                char *last_char;
 260
 261                /* Affinity was specified, translate it into mask */
 262                /* it is always in hex, skip "0x" if it exists */
 263                if (aff[0] == '0' && (aff[1]|0x20) == 'x')
 264                        aff += 2;
 265
 266                i = 0; /* bit pos in mask[] */
 267
 268                /* aff is ASCII hex string, accept very long masks in this form.
 269                 * Process hex string AABBCCDD... to ulong mask[]
 270                 * from the rightmost nibble, which is least-significant.
 271                 * Bits not fitting into mask[] are ignored: (example: 1234
 272                 * in 12340000000000000000000000000000000000000ff)
 273                 */
 274                last_char = strchrnul(aff, '\0');
 275                while (last_char > aff) {
 276                        char c;
 277                        ul val;
 278
 279                        last_char--;
 280                        c = *last_char;
 281                        if (isdigit(c))
 282                                val = c - '0';
 283                        else if ((c|0x20) >= 'a' && (c|0x20) <= 'f')
 284                                val = (c|0x20) - ('a' - 10);
 285                        else
 286                                bb_error_msg_and_die("bad affinity '%s'", aff);
 287
 288                        if (i < mask_size_in_bytes * 8) {
 289                                mask[i / BITS_UL] |= val << (i & MASK_UL);
 290                                //bb_error_msg("bit %d set", i);
 291                        }
 292                        /* else:
 293                         * We can error out here, but we don't.
 294                         * For one, kernel itself ignores bits in mask[]
 295                         * which do not map to any CPUs:
 296                         * if mask[] has one 32-bit long element,
 297                         * but you have only 8 CPUs, all bits beyond first 8
 298                         * are ignored, silently.
 299                         * No point in making bits past 31th to be errors.
 300                         */
 301                        i += 4;
 302                }
 303        }
 304
 305        /* Set pid's or our own (pid==0) affinity */
 306        if (sched_setaffinity(pid, mask_size_in_bytes, (void*)mask))
 307                bb_perror_msg_and_die("can't %cet pid %d's affinity", 's', pid);
 308        //bb_error_msg("set mask[0]:%lx", mask[0]);
 309
 310        if ((opts & OPT_p) && aff) { /* "-p <aff> <pid> [...ignored...]" */
 311                aff = NULL;
 312                goto print_aff; /* print new affinity and exit */
 313        }
 314        return 0;
 315}
 316
 317static int FAST_FUNC iter(const char *dn UNUSED_PARAM, struct dirent *ent, void *aff)
 318{
 319        if (isdigit(ent->d_name[0]))
 320                return process_pid_str(ent->d_name, option_mask32, aff);
 321        return 0;
 322}
 323
 324int taskset_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 325int taskset_main(int argc UNUSED_PARAM, char **argv)
 326{
 327        const char *pid_str;
 328        char *aff;
 329        unsigned opts;
 330
 331        /* NB: we mimic util-linux's taskset: -p does not take
 332         * an argument, i.e., "-pN" is NOT valid, only "-p N"!
 333         * Indeed, util-linux-2.13-pre7 uses:
 334         * getopt_long(argc, argv, "+pchV", ...), not "...p:..." */
 335
 336        opts = getopt32(argv, "^+" "pa"IF_FEATURE_TASKSET_CPULIST("c")
 337                        "\0" "-1" /* at least 1 arg */);
 338        argv += optind;
 339
 340        aff = *argv++;
 341        if (!(opts & OPT_p)) {
 342                /* <aff> <cmd...> */
 343                if (!*argv)
 344                        bb_show_usage();
 345                process_pid_str(NULL, opts, aff);
 346                BB_EXECVP_or_die(argv);
 347        }
 348
 349        pid_str = aff;
 350        if (*argv) /* "-p <aff> <pid> ...rest.is.ignored..." */
 351                pid_str = *argv;
 352        else
 353                aff = NULL;
 354
 355        if (opts & OPT_a) {
 356                char *dn;
 357                int r;
 358
 359                dn = xasprintf("/proc/%s/task", pid_str);
 360                r = iterate_on_dir(dn, iter, aff);
 361                IF_FEATURE_CLEAN_UP(free(dn);)
 362                if (r == 0)
 363                        return r; /* EXIT_SUCCESS */
 364                /* else: no /proc/PID/task, act as if no -a was given */
 365        }
 366        return process_pid_str(pid_str, opts, aff);
 367}
 368