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226 lines
6.0 KiB
C
226 lines
6.0 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 source tree.
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*/
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//config:config TASKSET
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//config: bool "taskset"
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//config: default n # doesn't build on some non-x86 targets (m68k)
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//config: help
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//config: Retrieve or set a processes's CPU affinity.
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//config: This requires sched_{g,s}etaffinity support in your libc.
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//config:
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//config:config FEATURE_TASKSET_FANCY
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//config: bool "Fancy output"
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//config: default y
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//config: depends on TASKSET
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//config: help
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//config: Add code for fancy output. This merely silences a compiler-warning
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//config: and adds about 135 Bytes. May be needed for machines with alot
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//config: of CPUs.
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//applet:IF_TASKSET(APPLET(taskset, BB_DIR_USR_BIN, BB_SUID_DROP))
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//kbuild:lib-$(CONFIG_TASKSET) += taskset.o
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//usage:#define taskset_trivial_usage
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//usage: "[-p] [MASK] [PID | PROG ARGS]"
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//usage:#define taskset_full_usage "\n\n"
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//usage: "Set or get CPU affinity\n"
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//usage: "\n -p Operate on an existing PID"
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//usage:
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//usage:#define taskset_example_usage
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//usage: "$ taskset 0x7 ./dgemm_test&\n"
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//usage: "$ taskset -p 0x1 $!\n"
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//usage: "pid 4790's current affinity mask: 7\n"
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//usage: "pid 4790's new affinity mask: 1\n"
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//usage: "$ taskset 0x7 /bin/sh -c './taskset -p 0x1 $$'\n"
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//usage: "pid 6671's current affinity mask: 1\n"
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//usage: "pid 6671's new affinity mask: 1\n"
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//usage: "$ taskset -p 1\n"
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//usage: "pid 1's current affinity mask: 3\n"
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/*
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Not yet implemented:
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* -a/--all-tasks (affect all threads)
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* -c/--cpu-list (specify CPUs via "1,3,5-7")
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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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CPU_ZERO(&mask);
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if (!ENABLE_FEATURE_TASKSET_FANCY) {
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unsigned i;
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unsigned long long m;
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/* Do not allow zero mask: */
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m = xstrtoull_range(aff, 0, 1, ULLONG_MAX);
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i = 0;
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do {
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if (m & 1)
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CPU_SET(i, &mask);
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i++;
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m >>= 1;
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} while (m != 0);
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} else {
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unsigned i;
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char *last_byte;
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char *bin;
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uint8_t bit_in_byte;
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/* Cheap way to get "long enough" buffer */
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bin = xstrdup(aff);
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if (aff[0] != '0' || (aff[1]|0x20) != 'x') {
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/* TODO: decimal/octal masks are still limited to 2^64 */
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unsigned long long m = xstrtoull_range(aff, 0, 1, ULLONG_MAX);
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bin += strlen(bin);
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last_byte = bin - 1;
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while (m) {
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*--bin = m & 0xff;
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m >>= 8;
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}
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} else {
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/* aff is "0x.....", we accept very long masks in this form */
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last_byte = hex2bin(bin, aff + 2, INT_MAX);
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if (!last_byte) {
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bad_aff:
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bb_error_msg_and_die("bad affinity '%s'", aff);
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}
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last_byte--; /* now points to the last byte */
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}
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i = 0;
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bit_in_byte = 1;
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while (last_byte >= bin) {
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if (bit_in_byte & *last_byte) {
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if (i >= CPU_SETSIZE)
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goto bad_aff;
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CPU_SET(i, &mask);
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//bb_error_msg("bit %d set", i);
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}
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i++;
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/* bit_in_byte is uint8_t! & 0xff is implied */
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bit_in_byte = (bit_in_byte << 1);
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if (!bit_in_byte) {
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bit_in_byte = 1;
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last_byte--;
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}
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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_or_die(argv);
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}
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