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| #include <stdio.h>
| #include <stdlib.h>
| #include <unistd.h>
| #include <linux/bitops.h>
| #include "api/fs/fs.h"
| #include "smt.h"
|
| int smt_on(void)
| {
| static bool cached;
| static int cached_result;
| int cpu;
| int ncpu;
|
| if (cached)
| return cached_result;
|
| if (sysfs__read_int("devices/system/cpu/smt/active", &cached_result) >= 0)
| goto done;
|
| ncpu = sysconf(_SC_NPROCESSORS_CONF);
| for (cpu = 0; cpu < ncpu; cpu++) {
| unsigned long long siblings;
| char *str;
| size_t strlen;
| char fn[256];
|
| snprintf(fn, sizeof fn,
| "devices/system/cpu/cpu%d/topology/core_cpus", cpu);
| if (sysfs__read_str(fn, &str, &strlen) < 0) {
| snprintf(fn, sizeof fn,
| "devices/system/cpu/cpu%d/topology/thread_siblings",
| cpu);
| if (sysfs__read_str(fn, &str, &strlen) < 0)
| continue;
| }
| /* Entry is hex, but does not have 0x, so need custom parser */
| siblings = strtoull(str, NULL, 16);
| free(str);
| if (hweight64(siblings) > 1) {
| cached_result = 1;
| cached = true;
| break;
| }
| }
| if (!cached) {
| cached_result = 0;
| done:
| cached = true;
| }
| return cached_result;
| }
|
|
