/*
* taskset.c - taskset
* Command-line utility for setting and retrieving a task's CPU affinity
*
* Robert Love <rml@tech9.net> 25 April 2002
*
* Linux kernels as of 2.5.8 provide the needed syscalls for
* working with a task's cpu affinity. Currently 2.4 does not
* support these syscalls, but patches are available at:
*
* http://www.kernel.org/pub/linux/kernel/people/rml/cpu-affinity/
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License, v2, as
* published by the Free Software Foundation
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* Copyright (C) 2004 Robert Love
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <getopt.h>
#include <sched.h>
#include <errno.h>
#include <string.h>
#include <ctype.h>
#include <sys/syscall.h>
#include "cpuset.h"
static void show_usage(const char *cmd)
{
fprintf(stderr, "taskset (%s)\n", PACKAGE_STRING);
fprintf(stderr, "usage: %s [options] [mask | cpu-list] [pid |"\
" cmd [args...]]\n", cmd);
fprintf(stderr, "set or get the affinity of a process\n\n");
fprintf(stderr, " -p, --pid "
"operate on existing given pid\n");
fprintf(stderr, " -c, --cpu-list "\
"display and specify cpus in list format\n");
fprintf(stderr, " -h, --help display this help\n");
fprintf(stderr, " -V, --version "\
"output version information\n\n");
fprintf(stderr, "The default behavior is to run a new command:\n");
fprintf(stderr, " %s 03 sshd -b 1024\n", cmd);
fprintf(stderr, "You can retrieve the mask of an existing task:\n");
fprintf(stderr, " %s -p 700\n", cmd);
fprintf(stderr, "Or set it:\n");
fprintf(stderr, " %s -p 03 700\n", cmd);
fprintf(stderr, "List format uses a comma-separated list instead"\
" of a mask:\n");
fprintf(stderr, " %s -pc 0,3,7-11 700\n", cmd);
fprintf(stderr, "Ranges in list format can take a stride argument:\n");
fprintf(stderr, " e.g. 0-31:2 is equivalent to mask 0x55555555\n\n");
}
/*
* Number of bits in a CPU bitmask on current system
*/
static int
max_number_of_cpus(void)
{
int n;
int cpus = 2048;
for (;;) {
unsigned long buffer[longsperbits(cpus)];
memset(buffer, 0, sizeof(buffer));
/* the library version does not return size of cpumask_t */
n = syscall(SYS_sched_getaffinity, 0, bytesperbits(cpus),
&buffer);
if (n < 0 && errno == EINVAL && cpus < 1024*1024) {
cpus *= 2;
continue;
}
return n*8;
}
fprintf (stderr, "cannot determine NR_CPUS; aborting");
exit(1);
return 0;
}
int main(int argc, char *argv[])
{
struct bitmask *new_mask, *cur_mask;
pid_t pid = 0;
int opt, err;
char *mstr;
char *cstr;
int c_opt = 0;
unsigned int cpus_configured;
int new_mask_byte_size, cur_mask_byte_size;
struct option longopts[] = {
{ "pid", 0, NULL, 'p' },
{ "cpu-list", 0, NULL, 'c' },
{ "help", 0, NULL, 'h' },
{ "version", 0, NULL, 'V' },
{ NULL, 0, NULL, 0 }
};
while ((opt = getopt_long(argc, argv, "+pchV", longopts, NULL)) != -1) {
int ret = 1;
switch (opt) {
case 'p':
pid = atoi(argv[argc - 1]);
break;
case 'c':
c_opt = 1;
break;
case 'V':
printf("taskset (%s)\n", PACKAGE_STRING);
return 0;
case 'h':
ret = 0;
default:
show_usage(argv[0]);
return ret;
}
}
if ((!pid && argc - optind < 2)
|| (pid && (argc - optind < 1 || argc - optind > 2))) {
show_usage(argv[0]);
return 1;
}
cpus_configured = max_number_of_cpus();
/*
* cur_mask is always used for the sched_getaffinity call
* On the sched_getaffinity the kernel demands a user mask of
* at least the size of its own cpumask_t.
*/
cur_mask = bitmask_alloc(cpus_configured);
if (!cur_mask) {
fprintf (stderr, "bitmask_alloc failed\n");
exit(1);
}
cur_mask_byte_size = bitmask_nbytes(cur_mask);
mstr = malloc(1 + cur_mask->size / 4);
cstr = malloc(7 * cur_mask->size);
/*
* new_mask is always used for the sched_setaffinity call
* On the sched_setaffinity the kernel will zero-fill its
* cpumask_t if the user's mask is shorter.
*/
new_mask = bitmask_alloc(cpus_configured);
if (!new_mask) {
fprintf (stderr, "bitmask_alloc failed\n");
exit(1);
}
new_mask_byte_size = bitmask_nbytes(new_mask);
if (pid) {
if (sched_getaffinity(pid, cur_mask_byte_size,
(cpu_set_t *)cur_mask->maskp) < 0) {
perror("sched_getaffinity");
fprintf(stderr, "failed to get pid %d's affinity\n",
pid);
return 1;
}
if (c_opt)
printf("pid %d's current affinity list: %s\n", pid,
cpuset_to_cstr(cur_mask, cstr));
else
printf("pid %d's current affinity mask: %s\n", pid,
cpuset_to_str(cur_mask, mstr));
if (argc - optind == 1)
return 0;
}
if (c_opt)
err = cstr_to_cpuset(new_mask, argv[optind]);
else
err = str_to_cpuset(new_mask, argv[optind]);
if (err) {
if (c_opt)
fprintf(stderr, "failed to parse CPU list %s\n",
argv[optind]);
else
fprintf(stderr, "failed to parse CPU mask %s\n",
argv[optind]);
return 1;
}
if (sched_setaffinity(pid, new_mask_byte_size,
(cpu_set_t *) new_mask->maskp) < 0) {
perror("sched_setaffinity");
fprintf(stderr, "failed to set pid %d's affinity.\n", pid);
return 1;
}
if (sched_getaffinity(pid, cur_mask_byte_size,
(cpu_set_t *)cur_mask->maskp) < 0) {
perror("sched_getaffinity");
fprintf(stderr, "failed to get pid %d's affinity.\n", pid);
return 1;
}
if (pid) {
if (c_opt)
printf("pid %d's new affinity list: %s\n", pid,
cpuset_to_cstr(cur_mask, cstr));
else
printf("pid %d's new affinity mask: %s\n", pid,
cpuset_to_str(cur_mask, mstr));
} else {
argv += optind + 1;
execvp(argv[0], argv);
perror("execvp");
fprintf(stderr, "failed to execute %s\n", argv[0]);
return 1;
}
return 0;
}
