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/* vi: set sw=4 ts=4: */
/*
* taskset - retrieve or set a processes' CPU affinity
* Copyright (c) 2006 Bernhard Reutner-Fischer
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
//config:config TASKSET
//config: bool "taskset"
//config: default n # doesn't build on some non-x86 targets (m68k)
//config: help
//config: Retrieve or set a processes's CPU affinity.
//config: This requires sched_{g,s}etaffinity support in your libc.
//config:
//config:config FEATURE_TASKSET_FANCY
//config: bool "Fancy output"
//config: default y
//config: depends on TASKSET
//config: help
//config: Add code for fancy output. This merely silences a compiler-warning
//config: and adds about 135 Bytes. May be needed for machines with alot
//config: of CPUs.
//applet:IF_TASKSET(APPLET(taskset, BB_DIR_USR_BIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_TASKSET) += taskset.o
//usage:#define taskset_trivial_usage
//usage: "[-p] [MASK] [PID | PROG ARGS]"
//usage:#define taskset_full_usage "\n\n"
//usage: "Set or get CPU affinity\n"
//usage: "\n -p Operate on an existing PID"
//usage:
//usage:#define taskset_example_usage
//usage: "$ taskset 0x7 ./dgemm_test&\n"
//usage: "$ taskset -p 0x1 $!\n"
//usage: "pid 4790's current affinity mask: 7\n"
//usage: "pid 4790's new affinity mask: 1\n"
//usage: "$ taskset 0x7 /bin/sh -c './taskset -p 0x1 $$'\n"
//usage: "pid 6671's current affinity mask: 1\n"
//usage: "pid 6671's new affinity mask: 1\n"
//usage: "$ taskset -p 1\n"
//usage: "pid 1's current affinity mask: 3\n"
/*
Not yet implemented:
* -a/--all-tasks (affect all threads)
* -c/--cpu-list (specify CPUs via "1,3,5-7")
*/
#include <sched.h>
#include "libbb.h"
#if ENABLE_FEATURE_TASKSET_FANCY
#define TASKSET_PRINTF_MASK "%s"
/* craft a string from the mask */
static char *from_cpuset(cpu_set_t *mask)
{
int i;
char *ret = NULL;
char *str = xzalloc((CPU_SETSIZE / 4) + 1); /* we will leak it */
for (i = CPU_SETSIZE - 4; i >= 0; i -= 4) {
int val = 0;
int off;
for (off = 0; off <= 3; ++off)
if (CPU_ISSET(i + off, mask))
val |= 1 << off;
if (!ret && val)
ret = str;
*str++ = bb_hexdigits_upcase[val] | 0x20;
}
return ret;
}
#else
#define TASKSET_PRINTF_MASK "%llx"
static unsigned long long from_cpuset(cpu_set_t *mask)
{
BUILD_BUG_ON(CPU_SETSIZE < 8*sizeof(int));
/* Take the least significant bits. Assume cpu_set_t is
* implemented as an array of unsigned long or unsigned
* int.
*/
if (CPU_SETSIZE < 8*sizeof(long))
return *(unsigned*)mask;
if (CPU_SETSIZE < 8*sizeof(long long))
return *(unsigned long*)mask;
# if BB_BIG_ENDIAN
if (sizeof(long long) > sizeof(long)) {
/* We can put two long in the long long, but they have to
* be swapped: the least significant word comes first in the
* array */
unsigned long *p = (void*)mask;
return p[0] + ((unsigned long long)p[1] << (8*sizeof(long)));
}
# endif
return *(unsigned long long*)mask;
}
#endif
int taskset_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int taskset_main(int argc UNUSED_PARAM, char **argv)
{
cpu_set_t mask;
pid_t pid = 0;
unsigned opt_p;
const char *current_new;
char *pid_str;
char *aff = aff; /* for compiler */
/* NB: we mimic util-linux's taskset: -p does not take
* an argument, i.e., "-pN" is NOT valid, only "-p N"!
* Indeed, util-linux-2.13-pre7 uses:
* getopt_long(argc, argv, "+pchV", ...), not "...p:..." */
opt_complementary = "-1"; /* at least 1 arg */
opt_p = getopt32(argv, "+p");
argv += optind;
if (opt_p) {
pid_str = *argv++;
if (*argv) { /* "-p <aff> <pid> ...rest.is.ignored..." */
aff = pid_str;
pid_str = *argv; /* NB: *argv != NULL in this case */
}
/* else it was just "-p <pid>", and *argv == NULL */
pid = xatoul_range(pid_str, 1, ((unsigned)(pid_t)ULONG_MAX) >> 1);
} else {
aff = *argv++; /* <aff> <cmd...> */
if (!*argv)
bb_show_usage();
}
current_new = "current\0new";
if (opt_p) {
print_aff:
if (sched_getaffinity(pid, sizeof(mask), &mask) < 0)
bb_perror_msg_and_die("can't %cet pid %d's affinity", 'g', pid);
printf("pid %d's %s affinity mask: "TASKSET_PRINTF_MASK"\n",
pid, current_new, from_cpuset(&mask));
if (!*argv) {
/* Either it was just "-p <pid>",
* or it was "-p <aff> <pid>" and we came here
* for the second time (see goto below) */
return EXIT_SUCCESS;
}
*argv = NULL;
current_new += 8; /* "new" */
}
/* Affinity was specified, translate it into cpu_set_t */
CPU_ZERO(&mask);
if (!ENABLE_FEATURE_TASKSET_FANCY) {
unsigned i;
unsigned long long m;
/* Do not allow zero mask: */
m = xstrtoull_range(aff, 0, 1, ULLONG_MAX);
i = 0;
do {
if (m & 1)
CPU_SET(i, &mask);
i++;
m >>= 1;
} while (m != 0);
} else {
unsigned i;
char *last_byte;
char *bin;
uint8_t bit_in_byte;
/* Cheap way to get "long enough" buffer */
bin = xstrdup(aff);
if (aff[0] != '0' || (aff[1]|0x20) != 'x') {
/* TODO: decimal/octal masks are still limited to 2^64 */
unsigned long long m = xstrtoull_range(aff, 0, 1, ULLONG_MAX);
bin += strlen(bin);
last_byte = bin - 1;
while (m) {
*--bin = m & 0xff;
m >>= 8;
}
} else {
/* aff is "0x.....", we accept very long masks in this form */
last_byte = hex2bin(bin, aff + 2, INT_MAX);
if (!last_byte) {
bad_aff:
bb_error_msg_and_die("bad affinity '%s'", aff);
}
last_byte--; /* now points to the last byte */
}
i = 0;
bit_in_byte = 1;
while (last_byte >= bin) {
if (bit_in_byte & *last_byte) {
if (i >= CPU_SETSIZE)
goto bad_aff;
CPU_SET(i, &mask);
//bb_error_msg("bit %d set", i);
}
i++;
/* bit_in_byte is uint8_t! & 0xff is implied */
bit_in_byte = (bit_in_byte << 1);
if (!bit_in_byte) {
bit_in_byte = 1;
last_byte--;
}
}
}
/* Set pid's or our own (pid==0) affinity */
if (sched_setaffinity(pid, sizeof(mask), &mask))
bb_perror_msg_and_die("can't %cet pid %d's affinity", 's', pid);
if (!argv[0]) /* "-p <aff> <pid> [...ignored...]" */
goto print_aff; /* print new affinity and exit */
BB_EXECVP_or_die(argv);
}
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