path: root/miscutils/taskset.c (plain)
blob: 71ad825a29ef03d025ae4d050748420e2c9fef53

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 source tree.
7	*/
8
9	//usage:#define taskset_trivial_usage
10	//usage: "[-p] [MASK] [PID | PROG ARGS]"
11	//usage:#define taskset_full_usage "\n\n"
12	//usage: "Set or get CPU affinity\n"
13	//usage: "\n -p Operate on an existing PID"
14	//usage:
15	//usage:#define taskset_example_usage
16	//usage: "$ taskset 0x7 ./dgemm_test&\n"
17	//usage: "$ taskset -p 0x1 $!\n"
18	//usage: "pid 4790's current affinity mask: 7\n"
19	//usage: "pid 4790's new affinity mask: 1\n"
20	//usage: "$ taskset 0x7 /bin/sh -c './taskset -p 0x1 $$'\n"
21	//usage: "pid 6671's current affinity mask: 1\n"
22	//usage: "pid 6671's new affinity mask: 1\n"
23	//usage: "$ taskset -p 1\n"
24	//usage: "pid 1's current affinity mask: 3\n"
25
26	#ifdef BIONIC_ICS
27	#define _GNU_SOURCE 1
28	#endif
29
30	#include <sched.h>
31	#include "libbb.h"
32
33	#if ENABLE_FEATURE_TASKSET_FANCY
34	#define TASKSET_PRINTF_MASK "%s"
35	/* craft a string from the mask */
36	static char *from_cpuset(cpu_set_t *mask)
37	{
38	int i;
39	char *ret = NULL;
40	char *str = xzalloc((CPU_SETSIZE / 4) + 1); /* we will leak it */
41
42	for (i = CPU_SETSIZE - 4; i >= 0; i -= 4) {
43	int val = 0;
44	int off;
45	for (off = 0; off <= 3; ++off)
46	if (CPU_ISSET(i + off, mask))
47	val |= 1 << off;
48	if (!ret && val)
49	ret = str;
50	*str++ = bb_hexdigits_upcase[val] | 0x20;
51	}
52	return ret;
53	}
54	#else
55	#define TASKSET_PRINTF_MASK "%llx"
56	static unsigned long long from_cpuset(cpu_set_t *mask)
57	{
58	struct BUG_CPU_SETSIZE_is_too_small {
59	char BUG_CPU_SETSIZE_is_too_small[
60	CPU_SETSIZE < sizeof(int) ? -1 : 1];
61	};
62	char *p = (void*)mask;
63
64	/* Take the least significant bits. Careful!
65	* Consider both CPU_SETSIZE=4 and CPU_SETSIZE=1024 cases
66	*/
67	#if BB_BIG_ENDIAN
68	/* For big endian, it means LAST bits */
69	if (CPU_SETSIZE < sizeof(long))
70	p += CPU_SETSIZE - sizeof(int);
71	else if (CPU_SETSIZE < sizeof(long long))
72	p += CPU_SETSIZE - sizeof(long);
73	else
74	p += CPU_SETSIZE - sizeof(long long);
75	#endif
76	if (CPU_SETSIZE < sizeof(long))
77	return *(unsigned*)p;
78	if (CPU_SETSIZE < sizeof(long long))
79	return *(unsigned long*)p;
80	return *(unsigned long long*)p;
81	}
82	#endif
83
84
85	int taskset_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
86	int taskset_main(int argc UNUSED_PARAM, char **argv)
87	{
88	cpu_set_t mask;
89	pid_t pid = 0;
90	unsigned opt_p;
91	const char *current_new;
92	char *pid_str;
93	char *aff = NULL;
94
95	/* NB: we mimic util-linux's taskset: -p does not take
96	* an argument, i.e., "-pN" is NOT valid, only "-p N"!
97	* Indeed, util-linux-2.13-pre7 uses:
98	* getopt_long(argc, argv, "+pchV", ...), not "...p:..." */
99
100	opt_complementary = "-1"; /* at least 1 arg */
101	opt_p = getopt32(argv, "+p");
102	argv += optind;
103
104	if (opt_p) {
105	pid_str = *argv++;
106	if (*argv) { /* "-p <aff> <pid> ...rest.is.ignored..." */
107	aff = pid_str;
108	pid_str = *argv; /* NB: *argv != NULL in this case */
109	}
110	/* else it was just "-p <pid>", and *argv == NULL */
111	pid = xatoul_range(pid_str, 1, ((unsigned)(pid_t)ULONG_MAX) >> 1);
112	} else {
113	aff = *argv++; /* <aff> <cmd...> */
114	if (!*argv)
115	bb_show_usage();
116	}
117
118	current_new = "current\0new";
119	if (opt_p) {
120	print_aff:
121	if (sched_getaffinity(pid, sizeof(mask), &mask) < 0)
122	bb_perror_msg_and_die("can't %cet pid %d's affinity", 'g', pid);
123	printf("pid %d's %s affinity mask: "TASKSET_PRINTF_MASK"\n",
124	pid, current_new, from_cpuset(&mask));
125	if (!*argv) {
126	/* Either it was just "-p <pid>",
127	* or it was "-p <aff> <pid>" and we came here
128	* for the second time (see goto below) */
129	return EXIT_SUCCESS;
130	}
131	*argv = NULL;
132	current_new += 8; /* "new" */
133	}
134
135	{ /* Affinity was specified, translate it into cpu_set_t */
136	unsigned i;
137	/* Do not allow zero mask: */
138	unsigned long long m = xstrtoull_range(aff, 0, 1, ULLONG_MAX);
139	enum { CNT_BIT = CPU_SETSIZE < sizeof(m)*8 ? CPU_SETSIZE : sizeof(m)*8 };
140
141	CPU_ZERO(&mask);
142	for (i = 0; i < CNT_BIT; i++) {
143	unsigned long long bit = (1ULL << i);
144	if (bit & m)
145	CPU_SET(i, &mask);
146	}
147	}
148
149	/* Set pid's or our own (pid==0) affinity */
150	if (sched_setaffinity(pid, sizeof(mask), &mask))
151	bb_perror_msg_and_die("can't %cet pid %d's affinity", 's', pid);
152
153	if (!argv[0]) /* "-p <aff> <pid> [...ignored...]" */
154	goto print_aff; /* print new affinity and exit */
155
156	BB_EXECVP_or_die(argv);
157	}
158