138 lines
3.6 KiB
C
138 lines
3.6 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* taskset - retrieve or set a processes' CPU affinity
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* Copyright (c) 2006 Bernhard Reutner-Fischer
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*
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* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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*/
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#include <sched.h>
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#include "libbb.h"
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#if ENABLE_FEATURE_TASKSET_FANCY
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#define TASKSET_PRINTF_MASK "%s"
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/* craft a string from the mask */
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static char *from_cpuset(cpu_set_t *mask)
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{
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int i;
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char *ret = NULL;
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char *str = xzalloc((CPU_SETSIZE / 4) + 1); /* we will leak it */
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for (i = CPU_SETSIZE - 4; i >= 0; i -= 4) {
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int val = 0;
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int off;
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for (off = 0; off <= 3; ++off)
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if (CPU_ISSET(i + off, mask))
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val |= 1 << off;
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if (!ret && val)
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ret = str;
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*str++ = bb_hexdigits_upcase[val] | 0x20;
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}
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return ret;
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}
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#else
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#define TASKSET_PRINTF_MASK "%llx"
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static unsigned long long from_cpuset(cpu_set_t *mask)
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{
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struct BUG_CPU_SETSIZE_is_too_small {
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char BUG_CPU_SETSIZE_is_too_small[
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CPU_SETSIZE < sizeof(int) ? -1 : 1];
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};
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char *p = (void*)mask;
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/* Take the least significant bits. Careful!
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* Consider both CPU_SETSIZE=4 and CPU_SETSIZE=1024 cases
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*/
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#if BB_BIG_ENDIAN
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/* For big endian, it means LAST bits */
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if (CPU_SETSIZE < sizeof(long))
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p += CPU_SETSIZE - sizeof(int);
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else if (CPU_SETSIZE < sizeof(long long))
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p += CPU_SETSIZE - sizeof(long);
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else
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p += CPU_SETSIZE - sizeof(long long);
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#endif
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if (CPU_SETSIZE < sizeof(long))
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return *(unsigned*)p;
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if (CPU_SETSIZE < sizeof(long long))
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return *(unsigned long*)p;
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return *(unsigned long long*)p;
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}
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#endif
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int taskset_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int taskset_main(int argc UNUSED_PARAM, char **argv)
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{
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cpu_set_t mask;
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pid_t pid = 0;
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unsigned opt_p;
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const char *current_new;
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char *pid_str;
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char *aff = aff; /* for compiler */
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/* NB: we mimic util-linux's taskset: -p does not take
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* an argument, i.e., "-pN" is NOT valid, only "-p N"!
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* Indeed, util-linux-2.13-pre7 uses:
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* getopt_long(argc, argv, "+pchV", ...), not "...p:..." */
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opt_complementary = "-1"; /* at least 1 arg */
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opt_p = getopt32(argv, "+p");
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argv += optind;
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if (opt_p) {
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pid_str = *argv++;
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if (*argv) { /* "-p <aff> <pid> ...rest.is.ignored..." */
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aff = pid_str;
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pid_str = *argv; /* NB: *argv != NULL in this case */
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}
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/* else it was just "-p <pid>", and *argv == NULL */
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pid = xatoul_range(pid_str, 1, ((unsigned)(pid_t)ULONG_MAX) >> 1);
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} else {
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aff = *argv++; /* <aff> <cmd...> */
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if (!*argv)
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bb_show_usage();
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}
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current_new = "current\0new";
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if (opt_p) {
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print_aff:
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if (sched_getaffinity(pid, sizeof(mask), &mask) < 0)
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bb_perror_msg_and_die("can't %cet pid %d's affinity", 'g', pid);
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printf("pid %d's %s affinity mask: "TASKSET_PRINTF_MASK"\n",
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pid, current_new, from_cpuset(&mask));
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if (!*argv) {
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/* Either it was just "-p <pid>",
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* or it was "-p <aff> <pid>" and we came here
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* for the second time (see goto below) */
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return EXIT_SUCCESS;
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}
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*argv = NULL;
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current_new += 8; /* "new" */
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}
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{ /* Affinity was specified, translate it into cpu_set_t */
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unsigned i;
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/* Do not allow zero mask: */
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unsigned long long m = xstrtoull_range(aff, 0, 1, ULLONG_MAX);
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enum { CNT_BIT = CPU_SETSIZE < sizeof(m)*8 ? CPU_SETSIZE : sizeof(m)*8 };
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CPU_ZERO(&mask);
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for (i = 0; i < CNT_BIT; i++) {
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unsigned long long bit = (1ULL << i);
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if (bit & m)
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CPU_SET(i, &mask);
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}
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}
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/* Set pid's or our own (pid==0) affinity */
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if (sched_setaffinity(pid, sizeof(mask), &mask))
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bb_perror_msg_and_die("can't %cet pid %d's affinity", 's', pid);
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if (!argv[0]) /* "-p <aff> <pid> [...ignored...]" */
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goto print_aff; /* print new affinity and exit */
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BB_EXECVP(argv[0], argv);
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bb_perror_msg_and_die("can't execute '%s'", argv[0]);
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}
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