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    Contents of /tags/mkinitrd-6_2_0/miscutils/taskset.c

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    Revision 994 - (show annotations) (download)
    Sun May 30 11:53:18 2010 UTC (14 years ago) by niro
    File MIME type: text/plain
    File size: 3712 byte(s) 
    tagged 'mkinitrd-6_2_0'
    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 */
    15 static 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"
    35 static 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
    64 int taskset_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
    65 int 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) /* "-p <aff> <pid> [...ignored...]" */
    133 goto print_aff; /* print new affinity and exit */
    134
    135 BB_EXECVP(*argv, argv);
    136 bb_simple_perror_msg_and_die(*argv);
    137 }