1 /* vi: set sw=4 ts=4: */
3 * taskset - retrieve or set a processes' CPU affinity
4 * Copyright (c) 2006 Bernhard Reutner-Fischer
6 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
9 //config:config TASKSET
10 //config: bool "taskset"
11 //config: default n # doesn't build on some non-x86 targets (m68k)
13 //config: Retrieve or set a processes's CPU affinity.
14 //config: This requires sched_{g,s}etaffinity support in your libc.
16 //config:config FEATURE_TASKSET_FANCY
17 //config: bool "Fancy output"
19 //config: depends on TASKSET
21 //config: Add code for fancy output. This merely silences a compiler-warning
22 //config: and adds about 135 Bytes. May be needed for machines with alot
25 //applet:IF_TASKSET(APPLET(taskset, BB_DIR_USR_BIN, BB_SUID_DROP))
26 //kbuild:lib-$(CONFIG_TASKSET) += taskset.o
28 //usage:#define taskset_trivial_usage
29 //usage: "[-p] [MASK] [PID | PROG ARGS]"
30 //usage:#define taskset_full_usage "\n\n"
31 //usage: "Set or get CPU affinity\n"
32 //usage: "\n -p Operate on an existing PID"
34 //usage:#define taskset_example_usage
35 //usage: "$ taskset 0x7 ./dgemm_test&\n"
36 //usage: "$ taskset -p 0x1 $!\n"
37 //usage: "pid 4790's current affinity mask: 7\n"
38 //usage: "pid 4790's new affinity mask: 1\n"
39 //usage: "$ taskset 0x7 /bin/sh -c './taskset -p 0x1 $$'\n"
40 //usage: "pid 6671's current affinity mask: 1\n"
41 //usage: "pid 6671's new affinity mask: 1\n"
42 //usage: "$ taskset -p 1\n"
43 //usage: "pid 1's current affinity mask: 3\n"
46 * -a/--all-tasks (affect all threads)
47 * -c/--cpu-list (specify CPUs via "1,3,5-7")
53 #if ENABLE_FEATURE_TASKSET_FANCY
54 #define TASKSET_PRINTF_MASK "%s"
55 /* craft a string from the mask */
56 static char *from_cpuset(cpu_set_t *mask)
60 char *str = xzalloc((CPU_SETSIZE / 4) + 1); /* we will leak it */
62 for (i = CPU_SETSIZE - 4; i >= 0; i -= 4) {
65 for (off = 0; off <= 3; ++off)
66 if (CPU_ISSET(i + off, mask))
70 *str++ = bb_hexdigits_upcase[val] | 0x20;
75 #define TASKSET_PRINTF_MASK "%llx"
76 static unsigned long long from_cpuset(cpu_set_t *mask)
78 BUILD_BUG_ON(CPU_SETSIZE < 8*sizeof(int));
80 /* Take the least significant bits. Assume cpu_set_t is
81 * implemented as an array of unsigned long or unsigned
84 if (CPU_SETSIZE < 8*sizeof(long))
85 return *(unsigned*)mask;
86 if (CPU_SETSIZE < 8*sizeof(long long))
87 return *(unsigned long*)mask;
89 if (sizeof(long long) > sizeof(long)) {
90 /* We can put two long in the long long, but they have to
91 * be swapped: the least significant word comes first in the
93 unsigned long *p = (void*)mask;
94 return p[0] + ((unsigned long long)p[1] << (8*sizeof(long)));
97 return *(unsigned long long*)mask;
102 int taskset_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
103 int taskset_main(int argc UNUSED_PARAM, char **argv)
108 const char *current_new;
110 char *aff = aff; /* for compiler */
112 /* NB: we mimic util-linux's taskset: -p does not take
113 * an argument, i.e., "-pN" is NOT valid, only "-p N"!
114 * Indeed, util-linux-2.13-pre7 uses:
115 * getopt_long(argc, argv, "+pchV", ...), not "...p:..." */
117 opt_complementary = "-1"; /* at least 1 arg */
118 opt_p = getopt32(argv, "+p");
123 if (*argv) { /* "-p <aff> <pid> ...rest.is.ignored..." */
125 pid_str = *argv; /* NB: *argv != NULL in this case */
127 /* else it was just "-p <pid>", and *argv == NULL */
128 pid = xatoul_range(pid_str, 1, ((unsigned)(pid_t)ULONG_MAX) >> 1);
130 aff = *argv++; /* <aff> <cmd...> */
135 current_new = "current\0new";
138 if (sched_getaffinity(pid, sizeof(mask), &mask) < 0)
139 bb_perror_msg_and_die("can't %cet pid %d's affinity", 'g', pid);
140 printf("pid %d's %s affinity mask: "TASKSET_PRINTF_MASK"\n",
141 pid, current_new, from_cpuset(&mask));
143 /* Either it was just "-p <pid>",
144 * or it was "-p <aff> <pid>" and we came here
145 * for the second time (see goto below) */
149 current_new += 8; /* "new" */
152 /* Affinity was specified, translate it into cpu_set_t */
154 if (!ENABLE_FEATURE_TASKSET_FANCY) {
156 unsigned long long m;
158 /* Do not allow zero mask: */
159 m = xstrtoull_range(aff, 0, 1, ULLONG_MAX);
173 /* Cheap way to get "long enough" buffer */
176 if (aff[0] != '0' || (aff[1]|0x20) != 'x') {
177 /* TODO: decimal/octal masks are still limited to 2^64 */
178 unsigned long long m = xstrtoull_range(aff, 0, 1, ULLONG_MAX);
186 /* aff is "0x.....", we accept very long masks in this form */
187 last_byte = hex2bin(bin, aff + 2, INT_MAX);
190 bb_error_msg_and_die("bad affinity '%s'", aff);
192 last_byte--; /* now points to the last byte */
197 while (last_byte >= bin) {
198 if (bit_in_byte & *last_byte) {
199 if (i >= CPU_SETSIZE)
202 //bb_error_msg("bit %d set", i);
205 /* bit_in_byte is uint8_t! & 0xff is implied */
206 bit_in_byte = (bit_in_byte << 1);
214 /* Set pid's or our own (pid==0) affinity */
215 if (sched_setaffinity(pid, sizeof(mask), &mask))
216 bb_perror_msg_and_die("can't %cet pid %d's affinity", 's', pid);
218 if (!argv[0]) /* "-p <aff> <pid> [...ignored...]" */
219 goto print_aff; /* print new affinity and exit */
221 BB_EXECVP_or_die(argv);