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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 (4.2 kb)"
//config: default y
//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: Needed for machines with more than 32-64 CPUs:
//config: affinity parameter 0xHHHHHHHHHHHHHHHHHHHH can be arbitrarily long
//config: in this case. Otherwise, it is limited to sizeof(long).
//applet:IF_TASKSET(APPLET_NOEXEC(taskset, taskset, BB_DIR_USR_BIN, BB_SUID_DROP, taskset))
//kbuild:lib-$(CONFIG_TASKSET) += taskset.o
//usage:#define taskset_trivial_usage
//usage: "[-p] [HEXMASK] PID | PROG ARGS"
//usage:#define taskset_full_usage "\n\n"
//usage: "Set or get CPU affinity\n"
//usage: "\n -p Operate on an existing PID"
//usage:
//usage:#define taskset_example_usage
//usage: "$ 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)
* needs to get TIDs from /proc/PID/task/ and use _them_ as "pid" in sched_setaffinity(pid)
* -c/--cpu-list (specify CPUs via "1,3,5-7")
*/
#include <sched.h>
#include "libbb.h"
typedef unsigned long ul;
#define SZOF_UL (unsigned)(sizeof(ul))
#define BITS_UL (unsigned)(sizeof(ul)*8)
#define MASK_UL (unsigned)(sizeof(ul)*8 - 1)
#if ENABLE_FEATURE_TASKSET_FANCY
#define TASKSET_PRINTF_MASK "%s"
/* craft a string from the mask */
static char *from_mask(const ul *mask, unsigned sz_in_bytes)
{
char *str = xzalloc((sz_in_bytes+1) * 2); /* we will leak it */
char *p = str;
for (;;) {
ul v = *mask++;
if (SZOF_UL == 4)
p += sprintf(p, "%08lx", v);
if (SZOF_UL == 8)
p += sprintf(p, "%016lx", v);
if (SZOF_UL == 16)
p += sprintf(p, "%032lx", v); /* :) */
sz_in_bytes -= SZOF_UL;
if ((int)sz_in_bytes <= 0)
break;
}
while (str[0] == '0' && str[1])
str++;
return str;
}
#else
#define TASKSET_PRINTF_MASK "%lx"
static unsigned long long from_mask(ul *mask, unsigned sz_in_bytes UNUSED_PARAM)
{
return *mask;
}
#endif
static unsigned long *get_aff(int pid, unsigned *sz)
{
int r;
unsigned long *mask = NULL;
unsigned sz_in_bytes = *sz;
for (;;) {
mask = xrealloc(mask, sz_in_bytes);
r = sched_getaffinity(pid, sz_in_bytes, (void*)mask);
if (r == 0)
break;
sz_in_bytes *= 2;
if (errno == EINVAL && (int)sz_in_bytes > 0)
continue;
bb_perror_msg_and_die("can't %cet pid %d's affinity", 'g', pid);
}
//bb_error_msg("get mask[0]:%lx sz_in_bytes:%d", mask[0], sz_in_bytes);
*sz = sz_in_bytes;
return mask;
}
int taskset_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int taskset_main(int argc UNUSED_PARAM, char **argv)
{
ul *mask;
unsigned mask_size_in_bytes;
pid_t pid = 0;
unsigned opt_p;
const char *current_new;
char *aff;
/* 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_p = getopt32(argv, "^+" "p" "\0" "-1" /* at least 1 arg */);
argv += optind;
aff = *argv++;
if (opt_p) {
char *pid_str = aff;
if (*argv) { /* "-p <aff> <pid> ...rest.is.ignored..." */
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> <cmd...> */
if (!*argv)
bb_show_usage();
}
mask_size_in_bytes = SZOF_UL;
current_new = "current";
print_aff:
mask = get_aff(pid, &mask_size_in_bytes);
if (opt_p) {
printf("pid %d's %s affinity mask: "TASKSET_PRINTF_MASK"\n",
pid, current_new, from_mask(mask, mask_size_in_bytes));
if (*argv == NULL) {
/* 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 = "new";
}
memset(mask, 0, mask_size_in_bytes);
/* Affinity was specified, translate it into mask */
/* it is always in hex, skip "0x" if it exists */
if (aff[0] == '0' && (aff[1]|0x20) == 'x')
aff += 2;
if (!ENABLE_FEATURE_TASKSET_FANCY) {
mask[0] = xstrtoul(aff, 16);
} else {
unsigned i;
char *last_char;
i = 0; /* bit pos in mask[] */
/* aff is ASCII hex string, accept very long masks in this form.
* Process hex string AABBCCDD... to ulong mask[]
* from the rightmost nibble, which is least-significant.
* Bits not fitting into mask[] are ignored: (example: 1234
* in 12340000000000000000000000000000000000000ff)
*/
last_char = strchrnul(aff, '\0');
while (last_char > aff) {
char c;
ul val;
last_char--;
c = *last_char;
if (isdigit(c))
val = c - '0';
else if ((c|0x20) >= 'a' && (c|0x20) <= 'f')
val = (c|0x20) - ('a' - 10);
else
bb_error_msg_and_die("bad affinity '%s'", aff);
if (i < mask_size_in_bytes * 8) {
mask[i / BITS_UL] |= val << (i & MASK_UL);
//bb_error_msg("bit %d set", i);
}
/* else:
* We can error out here, but we don't.
* For one, kernel itself ignores bits in mask[]
* which do not map to any CPUs:
* if mask[] has one 32-bit long element,
* but you have only 8 CPUs, all bits beyond first 8
* are ignored, silently.
* No point in making bits past 31th to be errors.
*/
i += 4;
}
}
/* Set pid's or our own (pid==0) affinity */
if (sched_setaffinity(pid, mask_size_in_bytes, (void*)mask))
bb_perror_msg_and_die("can't %cet pid %d's affinity", 's', pid);
//bb_error_msg("set mask[0]:%lx", mask[0]);
if (!argv[0]) /* "-p <aff> <pid> [...ignored...]" */
goto print_aff; /* print new affinity and exit */
BB_EXECVP_or_die(argv);
}
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