busybox/util-linux/taskset.c

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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).
//config:
//config:config FEATURE_TASKSET_CPULIST
//config: bool "CPU list support (-c option)"
//config: default y
//config: depends on FEATURE_TASKSET_FANCY
//config: help
//config: Add support for taking/printing affinity as CPU list when '-c'
//config: option is used. For example, it prints '0-3,7' instead of mask '8f'.
//applet:IF_TASKSET(APPLET_NOEXEC(taskset, taskset, BB_DIR_USR_BIN, BB_SUID_DROP, taskset))
//kbuild:lib-$(CONFIG_TASKSET) += taskset.o
//usage:#define taskset_trivial_usage
//usage: "[-ap] [HEXMASK"IF_FEATURE_TASKSET_CPULIST(" | -c LIST")"] { PID | PROG ARGS }"
//usage:#define taskset_full_usage "\n\n"
//usage: "Set or get CPU affinity\n"
//usage: "\n -p Operate on PID"
//usage: "\n -a Operate on all threads"
//usage: "\n -c Affinity is a list, not mask"
//usage:
//usage:#define taskset_example_usage
//usage: "$ 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;
}
#if ENABLE_FEATURE_TASKSET_CPULIST
/*
* Parse the CPU list and set the mask accordingly.
*
* The list element can be either a CPU index or a range of CPU indices.
* Example: "1,3,5-7". Stride can be specified: "0-7:2" is "0,2,4,6".
* Note: leading and trailing whitespace is not allowed.
* util-linux 2.31 allows leading and sometimes trailing whitespace:
* ok: taskset -c ' 1, 2'
* ok: taskset -c ' 1 , 2'
* ok: taskset -c ' 1-7: 2 ,8'
* not ok: taskset -c ' 1 '
* not ok: taskset -c ' 1-7: 2 '
*/
static void parse_cpulist(ul *mask, unsigned max, char *s)
{
char *aff = s;
for (;;) {
unsigned bit, end;
unsigned stride = 1;
bit = end = bb_strtou(s, &s, 10);
if (*s == '-') {
s++;
end = bb_strtou(s, &s, 10);
if (*s == ':') {
s++;
stride = bb_strtou(s, &s, 10);
}
}
if ((*s != ',' && *s != '\0')
|| bit > end
|| end == UINT_MAX /* bb_strtou returns this on malformed / ERANGE numbers */
|| (stride - 1) > (UINT_MAX / 4)
/* disallow 0, malformed input, and too large stride prone to overflows */
) {
bb_error_msg_and_die("bad affinity '%s'", aff);
}
while (bit <= end && bit < max) {
mask[bit / BITS_UL] |= (1UL << (bit & MASK_UL));
bit += stride;
}
if (*s == '\0')
break;
s++;
}
}
static void print_cpulist(const ul *mask, unsigned mask_size_in_bytes)
{
const ul *mask_end;
const char *delim;
unsigned pos;
ul bit;
mask_end = mask + mask_size_in_bytes / sizeof(mask[0]);
delim = "";
pos = 0;
bit = 1;
for (;;) {
if (*mask & bit) {
unsigned onebit = pos + 1;
printf("%s%u", delim, pos);
do {
pos++;
bit <<= 1;
if (bit == 0) {
mask++;
if (mask >= mask_end)
break;
bit = 1;
}
} while (*mask & bit);
if (onebit != pos)
printf("-%u", pos - 1);
delim = ",";
}
pos++;
bit <<= 1;
if (bit == 0) {
mask++;
if (mask >= mask_end)
break;
bit = 1;
}
}
bb_putchar('\n');
}
#endif
enum {
OPT_p = 1 << 0,
OPT_a = 1 << 1,
OPT_c = (1 << 2) * ENABLE_FEATURE_TASKSET_CPULIST,
};
static int process_pid_str(const char *pid_str, unsigned opts, char *aff)
{
ul *mask;
unsigned mask_size_in_bytes;
const char *current_new;
pid_t pid = !pid_str ? 0 : xatou_range(pid_str, 1, INT_MAX); /* disallow "0": "taskset -p 0" should fail */
mask_size_in_bytes = SZOF_UL;
current_new = "current";
print_aff:
mask = get_aff(pid, &mask_size_in_bytes);
if (opts & OPT_p) {
#if ENABLE_FEATURE_TASKSET_CPULIST
if (opts & OPT_c) {
printf("pid %d's %s affinity list: ", pid, current_new);
print_cpulist(mask, mask_size_in_bytes);
} else
#endif
printf("pid %d's %s affinity mask: "TASKSET_PRINTF_MASK"\n",
pid, current_new, from_mask(mask, mask_size_in_bytes));
if (!aff) {
/* Either it was just "-p <pid>",
* or it was "-p <aff> <pid>" and we came here
* for the second time (see goto below) */
return 0;
}
current_new = "new";
}
memset(mask, 0, mask_size_in_bytes);
if (!ENABLE_FEATURE_TASKSET_FANCY) {
/* 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;
mask[0] = xstrtoul(aff, 16);
}
#if ENABLE_FEATURE_TASKSET_CPULIST
else if (opts & OPT_c) {
parse_cpulist(mask, mask_size_in_bytes * 8, aff);
}
#endif
else {
unsigned i;
char *last_char;
/* 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;
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 ((opts & OPT_p) && aff) { /* "-p <aff> <pid> [...ignored...]" */
aff = NULL;
goto print_aff; /* print new affinity and exit */
}
return 0;
}
static int FAST_FUNC iter(const char *dn UNUSED_PARAM, struct dirent *ent, void *aff)
{
if (isdigit(ent->d_name[0]))
return process_pid_str(ent->d_name, option_mask32, aff);
return 0;
}
int taskset_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int taskset_main(int argc UNUSED_PARAM, char **argv)
{
const char *pid_str;
char *aff;
unsigned opts;
/* 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:..." */
opts = getopt32(argv, "^+" "pa"IF_FEATURE_TASKSET_CPULIST("c")
"\0" "-1" /* at least 1 arg */);
argv += optind;
aff = *argv++;
if (!(opts & OPT_p)) {
/* <aff> <cmd...> */
if (!*argv)
bb_show_usage();
process_pid_str(NULL, opts, aff);
BB_EXECVP_or_die(argv);
}
pid_str = aff;
if (*argv) /* "-p <aff> <pid> ...rest.is.ignored..." */
pid_str = *argv;
else
aff = NULL;
if (opts & OPT_a) {
char *dn;
int r;
dn = xasprintf("/proc/%s/task", pid_str);
r = iterate_on_dir(dn, iter, aff);
IF_FEATURE_CLEAN_UP(free(dn);)
if (r == 0)
return r; /* EXIT_SUCCESS */
/* else: no /proc/PID/task, act as if no -a was given */
}
return process_pid_str(pid_str, opts, aff);
}