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 //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"
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"
29 #if ENABLE_FEATURE_TASKSET_FANCY
30 #define TASKSET_PRINTF_MASK "%s"
31 /* craft a string from the mask */
32 static char *from_cpuset(cpu_set_t
*mask
)
36 char *str
= xzalloc((CPU_SETSIZE
/ 4) + 1); /* we will leak it */
38 for (i
= CPU_SETSIZE
- 4; i
>= 0; i
-= 4) {
41 for (off
= 0; off
<= 3; ++off
)
42 if (CPU_ISSET(i
+ off
, mask
))
46 *str
++ = bb_hexdigits_upcase
[val
] | 0x20;
51 #define TASKSET_PRINTF_MASK "%llx"
52 static unsigned long long from_cpuset(cpu_set_t
*mask
)
54 struct BUG_CPU_SETSIZE_is_too_small
{
55 char BUG_CPU_SETSIZE_is_too_small
[
56 CPU_SETSIZE
< sizeof(int) ? -1 : 1];
58 char *p
= (void*)mask
;
60 /* Take the least significant bits. Careful!
61 * Consider both CPU_SETSIZE=4 and CPU_SETSIZE=1024 cases
64 /* For big endian, it means LAST bits */
65 if (CPU_SETSIZE
< sizeof(long))
66 p
+= CPU_SETSIZE
- sizeof(int);
67 else if (CPU_SETSIZE
< sizeof(long long))
68 p
+= CPU_SETSIZE
- sizeof(long);
70 p
+= CPU_SETSIZE
- sizeof(long long);
72 if (CPU_SETSIZE
< sizeof(long))
74 if (CPU_SETSIZE
< sizeof(long long))
75 return *(unsigned long*)p
;
76 return *(unsigned long long*)p
;
81 int taskset_main(int argc
, char **argv
) MAIN_EXTERNALLY_VISIBLE
;
82 int taskset_main(int argc UNUSED_PARAM
, char **argv
)
87 const char *current_new
;
89 char *aff
= aff
; /* for compiler */
91 /* NB: we mimic util-linux's taskset: -p does not take
92 * an argument, i.e., "-pN" is NOT valid, only "-p N"!
93 * Indeed, util-linux-2.13-pre7 uses:
94 * getopt_long(argc, argv, "+pchV", ...), not "...p:..." */
96 opt_complementary
= "-1"; /* at least 1 arg */
97 opt_p
= getopt32(argv
, "+p");
102 if (*argv
) { /* "-p <aff> <pid> ...rest.is.ignored..." */
104 pid_str
= *argv
; /* NB: *argv != NULL in this case */
106 /* else it was just "-p <pid>", and *argv == NULL */
107 pid
= xatoul_range(pid_str
, 1, ((unsigned)(pid_t
)ULONG_MAX
) >> 1);
109 aff
= *argv
++; /* <aff> <cmd...> */
114 current_new
= "current\0new";
117 if (sched_getaffinity(pid
, sizeof(mask
), &mask
) < 0)
118 bb_perror_msg_and_die("can't %cet pid %d's affinity", 'g', pid
);
119 printf("pid %d's %s affinity mask: "TASKSET_PRINTF_MASK
"\n",
120 pid
, current_new
, from_cpuset(&mask
));
122 /* Either it was just "-p <pid>",
123 * or it was "-p <aff> <pid>" and we came here
124 * for the second time (see goto below) */
128 current_new
+= 8; /* "new" */
131 { /* Affinity was specified, translate it into cpu_set_t */
133 /* Do not allow zero mask: */
134 unsigned long long m
= xstrtoull_range(aff
, 0, 1, ULLONG_MAX
);
135 enum { CNT_BIT
= CPU_SETSIZE
< sizeof(m
)*8 ? CPU_SETSIZE
: sizeof(m
)*8 };
138 for (i
= 0; i
< CNT_BIT
; i
++) {
139 unsigned long long bit
= (1ULL << i
);
145 /* Set pid's or our own (pid==0) affinity */
146 if (sched_setaffinity(pid
, sizeof(mask
), &mask
))
147 bb_perror_msg_and_die("can't %cet pid %d's affinity", 's', pid
);
149 if (!argv
[0]) /* "-p <aff> <pid> [...ignored...]" */
150 goto print_aff
; /* print new affinity and exit */
152 BB_EXECVP_or_die(argv
);