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Diffstat (limited to 'lib/cpuset.c')
| -rw-r--r-- | lib/cpuset.c | 397 |
1 files changed, 397 insertions, 0 deletions
diff --git a/lib/cpuset.c b/lib/cpuset.c new file mode 100644 index 0000000..011b688 --- /dev/null +++ b/lib/cpuset.c @@ -0,0 +1,397 @@ +/* + * Terminology: + * + * cpuset - (libc) cpu_set_t data structure represents set of CPUs + * cpumask - string with hex mask (e.g. "0x00000001") + * cpulist - string with CPU ranges (e.g. "0-3,5,7,8") + * + * Based on code from taskset.c and Linux kernel. + * + * This file may be redistributed under the terms of the + * GNU Lesser General Public License. + * + * Copyright (C) 2010 Karel Zak <kzak@redhat.com> + */ + +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <sched.h> +#include <errno.h> +#include <string.h> +#include <ctype.h> +#include <sys/syscall.h> + +#include "cpuset.h" +#include "c.h" + +static inline int val_to_char(int v) +{ + if (v >= 0 && v < 10) + return '0' + v; + if (v >= 10 && v < 16) + return ('a' - 10) + v; + return -1; +} + +static inline int char_to_val(int c) +{ + int cl; + + if (c >= '0' && c <= '9') + return c - '0'; + cl = tolower(c); + if (cl >= 'a' && cl <= 'f') + return cl + (10 - 'a'); + return -1; +} + +static const char *nexttoken(const char *q, int sep) +{ + if (q) + q = strchr(q, sep); + if (q) + q++; + return q; +} + +/* + * Number of bits in a CPU bitmask on current system + */ +int get_max_number_of_cpus(void) +{ +#ifdef SYS_sched_getaffinity + int n, cpus = 2048; + size_t setsize; + cpu_set_t *set = cpuset_alloc(cpus, &setsize, NULL); + + if (!set) + return -1; /* error */ + + for (;;) { + CPU_ZERO_S(setsize, set); + + /* the library version does not return size of cpumask_t */ + n = syscall(SYS_sched_getaffinity, 0, setsize, set); + + if (n < 0 && errno == EINVAL && cpus < 1024 * 1024) { + cpuset_free(set); + cpus *= 2; + set = cpuset_alloc(cpus, &setsize, NULL); + if (!set) + return -1; /* error */ + continue; + } + cpuset_free(set); + return n * 8; + } +#endif + return -1; +} + +/* + * Allocates a new set for ncpus and returns size in bytes and size in bits + */ +cpu_set_t *cpuset_alloc(int ncpus, size_t *setsize, size_t *nbits) +{ + cpu_set_t *set = CPU_ALLOC(ncpus); + + if (!set) + return NULL; + if (setsize) + *setsize = CPU_ALLOC_SIZE(ncpus); + if (nbits) + *nbits = cpuset_nbits(CPU_ALLOC_SIZE(ncpus)); + return set; +} + +void cpuset_free(cpu_set_t *set) +{ + CPU_FREE(set); +} + +#if !HAVE_DECL_CPU_ALLOC +/* Please, use CPU_COUNT_S() macro. This is fallback */ +int __cpuset_count_s(size_t setsize, const cpu_set_t *set) +{ + int s = 0; + const __cpu_mask *p = set->__bits; + const __cpu_mask *end = &set->__bits[setsize / sizeof (__cpu_mask)]; + + while (p < end) { + __cpu_mask l = *p++; + + if (l == 0) + continue; +# if LONG_BIT > 32 + l = (l & 0x5555555555555555ul) + ((l >> 1) & 0x5555555555555555ul); + l = (l & 0x3333333333333333ul) + ((l >> 2) & 0x3333333333333333ul); + l = (l & 0x0f0f0f0f0f0f0f0ful) + ((l >> 4) & 0x0f0f0f0f0f0f0f0ful); + l = (l & 0x00ff00ff00ff00fful) + ((l >> 8) & 0x00ff00ff00ff00fful); + l = (l & 0x0000ffff0000fffful) + ((l >> 16) & 0x0000ffff0000fffful); + l = (l & 0x00000000fffffffful) + ((l >> 32) & 0x00000000fffffffful); +# else + l = (l & 0x55555555ul) + ((l >> 1) & 0x55555555ul); + l = (l & 0x33333333ul) + ((l >> 2) & 0x33333333ul); + l = (l & 0x0f0f0f0ful) + ((l >> 4) & 0x0f0f0f0ful); + l = (l & 0x00ff00fful) + ((l >> 8) & 0x00ff00fful); + l = (l & 0x0000fffful) + ((l >> 16) & 0x0000fffful); +# endif + s += l; + } + return s; +} +#endif + +/* + * Returns human readable representation of the cpuset. The output format is + * a list of CPUs with ranges (for example, "0,1,3-9"). + */ +char *cpulist_create(char *str, size_t len, + cpu_set_t *set, size_t setsize) +{ + size_t i; + char *ptr = str; + int entry_made = 0; + size_t max = cpuset_nbits(setsize); + + for (i = 0; i < max; i++) { + if (CPU_ISSET_S(i, setsize, set)) { + int rlen; + size_t j, run = 0; + entry_made = 1; + for (j = i + 1; j < max; j++) { + if (CPU_ISSET_S(j, setsize, set)) + run++; + else + break; + } + if (!run) + rlen = snprintf(ptr, len, "%zu,", i); + else if (run == 1) { + rlen = snprintf(ptr, len, "%zu,%zu,", i, i + 1); + i++; + } else { + rlen = snprintf(ptr, len, "%zu-%zu,", i, i + run); + i += run; + } + if (rlen < 0 || (size_t) rlen >= len) + return NULL; + ptr += rlen; + len -= rlen; + } + } + ptr -= entry_made; + *ptr = '\0'; + + return str; +} + +/* + * Returns string with CPU mask. + */ +char *cpumask_create(char *str, size_t len, + cpu_set_t *set, size_t setsize) +{ + char *ptr = str; + char *ret = NULL; + int cpu; + + for (cpu = cpuset_nbits(setsize) - 4; cpu >= 0; cpu -= 4) { + char val = 0; + + if (len == (size_t) (ptr - str)) + break; + + if (CPU_ISSET_S(cpu, setsize, set)) + val |= 1; + if (CPU_ISSET_S(cpu + 1, setsize, set)) + val |= 2; + if (CPU_ISSET_S(cpu + 2, setsize, set)) + val |= 4; + if (CPU_ISSET_S(cpu + 3, setsize, set)) + val |= 8; + + if (!ret && val) + ret = ptr; + *ptr++ = val_to_char(val); + } + *ptr = '\0'; + return ret ? ret : ptr - 1; +} + +/* + * Parses string with CPUs mask. + */ +int cpumask_parse(const char *str, cpu_set_t *set, size_t setsize) +{ + int len = strlen(str); + const char *ptr = str + len - 1; + int cpu = 0; + + /* skip 0x, it's all hex anyway */ + if (len > 1 && !memcmp(str, "0x", 2L)) + str += 2; + + CPU_ZERO_S(setsize, set); + + while (ptr >= str) { + char val; + + /* cpu masks in /sys uses comma as a separator */ + if (*ptr == ',') + ptr--; + + val = char_to_val(*ptr); + if (val == (char) -1) + return -1; + if (val & 1) + CPU_SET_S(cpu, setsize, set); + if (val & 2) + CPU_SET_S(cpu + 1, setsize, set); + if (val & 4) + CPU_SET_S(cpu + 2, setsize, set); + if (val & 8) + CPU_SET_S(cpu + 3, setsize, set); + ptr--; + cpu += 4; + } + + return 0; +} + +/* + * Parses string with list of CPU ranges. + * Returns 0 on success. + * Returns 1 on error. + * Returns 2 if fail is set and a cpu number passed in the list doesn't fit + * into the cpu_set. If fail is not set cpu numbers that do not fit are + * ignored and 0 is returned instead. + */ +int cpulist_parse(const char *str, cpu_set_t *set, size_t setsize, int fail) +{ + size_t max = cpuset_nbits(setsize); + const char *p, *q; + int r = 0; + + q = str; + CPU_ZERO_S(setsize, set); + + while (p = q, q = nexttoken(q, ','), p) { + unsigned int a; /* beginning of range */ + unsigned int b; /* end of range */ + unsigned int s; /* stride */ + const char *c1, *c2; + char c; + + if ((r = sscanf(p, "%u%c", &a, &c)) < 1) + return 1; + b = a; + s = 1; + + c1 = nexttoken(p, '-'); + c2 = nexttoken(p, ','); + if (c1 != NULL && (c2 == NULL || c1 < c2)) { + if ((r = sscanf(c1, "%u%c", &b, &c)) < 1) + return 1; + c1 = nexttoken(c1, ':'); + if (c1 != NULL && (c2 == NULL || c1 < c2)) { + if ((r = sscanf(c1, "%u%c", &s, &c)) < 1) + return 1; + if (s == 0) + return 1; + } + } + + if (!(a <= b)) + return 1; + while (a <= b) { + if (fail && (a >= max)) + return 2; + CPU_SET_S(a, setsize, set); + a += s; + } + } + + if (r == 2) + return 1; + return 0; +} + +#ifdef TEST_PROGRAM_CPUSET + +#include <getopt.h> + +int main(int argc, char *argv[]) +{ + cpu_set_t *set; + size_t setsize, buflen, nbits; + char *buf, *mask = NULL, *range = NULL; + int ncpus = 2048, rc, c; + + static const struct option longopts[] = { + { "ncpus", 1, NULL, 'n' }, + { "mask", 1, NULL, 'm' }, + { "range", 1, NULL, 'r' }, + { NULL, 0, NULL, 0 } + }; + + while ((c = getopt_long(argc, argv, "n:m:r:", longopts, NULL)) != -1) { + switch(c) { + case 'n': + ncpus = atoi(optarg); + break; + case 'm': + mask = strdup(optarg); + break; + case 'r': + range = strdup(optarg); + break; + default: + goto usage_err; + } + } + + if (!mask && !range) + goto usage_err; + + set = cpuset_alloc(ncpus, &setsize, &nbits); + if (!set) + err(EXIT_FAILURE, "failed to allocate cpu set"); + + /* + fprintf(stderr, "ncpus: %d, cpuset bits: %zd, cpuset bytes: %zd\n", + ncpus, nbits, setsize); + */ + + buflen = 7 * nbits; + buf = malloc(buflen); + if (!buf) + err(EXIT_FAILURE, "failed to allocate cpu set buffer"); + + if (mask) + rc = cpumask_parse(mask, set, setsize); + else + rc = cpulist_parse(range, set, setsize, 0); + + if (rc) + errx(EXIT_FAILURE, "failed to parse string: %s", mask ? : range); + + printf("%-15s = %15s ", mask ? : range, + cpumask_create(buf, buflen, set, setsize)); + printf("[%s]\n", cpulist_create(buf, buflen, set, setsize)); + + free(buf); + free(mask); + free(range); + cpuset_free(set); + + return EXIT_SUCCESS; + +usage_err: + fprintf(stderr, + "usage: %s [--ncpus <num>] --mask <mask> | --range <list>", + program_invocation_short_name); + exit(EXIT_FAILURE); +} +#endif |