221 lines
6.3 KiB
C
221 lines
6.3 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 (4.2 kb)"
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//config: default y
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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: Needed for machines with more than 32-64 CPUs:
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//config: affinity parameter 0xHHHHHHHHHHHHHHHHHHHH can be arbitrarily long
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//config: in this case. Otherwise, it is limited to sizeof(long).
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//applet:IF_TASKSET(APPLET_NOEXEC(taskset, taskset, BB_DIR_USR_BIN, BB_SUID_DROP, taskset))
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//kbuild:lib-$(CONFIG_TASKSET) += taskset.o
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//usage:#define taskset_trivial_usage
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//usage: "[-p] [HEXMASK] PID | PROG ARGS"
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//usage:#define taskset_full_usage "\n\n"
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//usage: "Set or get CPU affinity\n"
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//usage: "\n -p Operate on an existing PID"
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//usage:
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//usage:#define taskset_example_usage
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//usage: "$ 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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* needs to get TIDs from /proc/PID/task/ and use _them_ as "pid" in sched_setaffinity(pid)
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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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typedef unsigned long ul;
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#define SZOF_UL (unsigned)(sizeof(ul))
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#define BITS_UL (unsigned)(sizeof(ul)*8)
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#define MASK_UL (unsigned)(sizeof(ul)*8 - 1)
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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_mask(const ul *mask, unsigned sz_in_bytes)
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{
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char *str = xzalloc((sz_in_bytes+1) * 2); /* we will leak it */
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char *p = str;
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for (;;) {
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ul v = *mask++;
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if (SZOF_UL == 4)
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p += sprintf(p, "%08lx", v);
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if (SZOF_UL == 8)
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p += sprintf(p, "%016lx", v);
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if (SZOF_UL == 16)
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p += sprintf(p, "%032lx", v); /* :) */
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sz_in_bytes -= SZOF_UL;
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if ((int)sz_in_bytes <= 0)
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break;
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}
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while (str[0] == '0' && str[1])
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str++;
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return str;
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}
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#else
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#define TASKSET_PRINTF_MASK "%lx"
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static unsigned long long from_mask(ul *mask, unsigned sz_in_bytes UNUSED_PARAM)
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{
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return *mask;
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}
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#endif
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static unsigned long *get_aff(int pid, unsigned *sz)
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{
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int r;
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unsigned long *mask = NULL;
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unsigned sz_in_bytes = *sz;
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for (;;) {
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mask = xrealloc(mask, sz_in_bytes);
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r = sched_getaffinity(pid, sz_in_bytes, (void*)mask);
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if (r == 0)
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break;
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sz_in_bytes *= 2;
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if (errno == EINVAL && (int)sz_in_bytes > 0)
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continue;
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bb_perror_msg_and_die("can't %cet pid %d's affinity", 'g', pid);
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}
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//bb_error_msg("get mask[0]:%lx sz_in_bytes:%d", mask[0], sz_in_bytes);
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*sz = sz_in_bytes;
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return mask;
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}
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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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ul *mask;
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unsigned mask_size_in_bytes;
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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 *aff;
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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_p = getopt32(argv, "^+" "p" "\0" "-1" /* at least 1 arg */);
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argv += optind;
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aff = *argv++;
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if (opt_p) {
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char *pid_str = aff;
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if (*argv) { /* "-p <aff> <pid> ...rest.is.ignored..." */
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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> <cmd...> */
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if (!*argv)
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bb_show_usage();
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}
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mask_size_in_bytes = SZOF_UL;
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current_new = "current";
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print_aff:
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mask = get_aff(pid, &mask_size_in_bytes);
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if (opt_p) {
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printf("pid %d's %s affinity mask: "TASKSET_PRINTF_MASK"\n",
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pid, current_new, from_mask(mask, mask_size_in_bytes));
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if (*argv == NULL) {
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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 = "new";
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}
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memset(mask, 0, mask_size_in_bytes);
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/* Affinity was specified, translate it into mask */
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/* it is always in hex, skip "0x" if it exists */
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if (aff[0] == '0' && (aff[1]|0x20) == 'x')
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aff += 2;
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if (!ENABLE_FEATURE_TASKSET_FANCY) {
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mask[0] = xstrtoul(aff, 16);
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} else {
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unsigned i;
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char *last_char;
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i = 0; /* bit pos in mask[] */
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/* aff is ASCII hex string, accept very long masks in this form.
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* Process hex string AABBCCDD... to ulong mask[]
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* from the rightmost nibble, which is least-significant.
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* Bits not fitting into mask[] are ignored: (example: 1234
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* in 12340000000000000000000000000000000000000ff)
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*/
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last_char = strchrnul(aff, '\0');
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while (last_char > aff) {
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char c;
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ul val;
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last_char--;
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c = *last_char;
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if (isdigit(c))
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val = c - '0';
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else if ((c|0x20) >= 'a' && (c|0x20) <= 'f')
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val = (c|0x20) - ('a' - 10);
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else
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bb_error_msg_and_die("bad affinity '%s'", aff);
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if (i < mask_size_in_bytes * 8) {
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mask[i / BITS_UL] |= val << (i & MASK_UL);
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//bb_error_msg("bit %d set", i);
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}
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/* else:
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* We can error out here, but we don't.
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* For one, kernel itself ignores bits in mask[]
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* which do not map to any CPUs:
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* if mask[] has one 32-bit long element,
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* but you have only 8 CPUs, all bits beyond first 8
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* are ignored, silently.
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* No point in making bits past 31th to be errors.
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*/
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i += 4;
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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, mask_size_in_bytes, (void*)mask))
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bb_perror_msg_and_die("can't %cet pid %d's affinity", 's', pid);
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//bb_error_msg("set mask[0]:%lx", mask[0]);
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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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