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Diffstat (limited to 'util-linux/taskset.c')
| -rw-r--r-- | util-linux/taskset.c | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/util-linux/taskset.c b/util-linux/taskset.c new file mode 100644 index 000000000..94a07383a --- /dev/null +++ b/util-linux/taskset.c @@ -0,0 +1,221 @@ +/* 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 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(taskset, BB_DIR_USR_BIN, BB_SUID_DROP)) +//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_complementary = "-1"; /* at least 1 arg */ + opt_p = getopt32(argv, "+p"); + 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); +} |