1*4882a593Smuzhiyun #include <stdio.h>
2*4882a593Smuzhiyun #include <stdlib.h>
3*4882a593Smuzhiyun #include <unistd.h>
4*4882a593Smuzhiyun #include <linux/bitops.h>
5*4882a593Smuzhiyun #include "api/fs/fs.h"
6*4882a593Smuzhiyun #include "smt.h"
7*4882a593Smuzhiyun
smt_on(void)8*4882a593Smuzhiyun int smt_on(void)
9*4882a593Smuzhiyun {
10*4882a593Smuzhiyun static bool cached;
11*4882a593Smuzhiyun static int cached_result;
12*4882a593Smuzhiyun int cpu;
13*4882a593Smuzhiyun int ncpu;
14*4882a593Smuzhiyun
15*4882a593Smuzhiyun if (cached)
16*4882a593Smuzhiyun return cached_result;
17*4882a593Smuzhiyun
18*4882a593Smuzhiyun if (sysfs__read_int("devices/system/cpu/smt/active", &cached_result) >= 0)
19*4882a593Smuzhiyun goto done;
20*4882a593Smuzhiyun
21*4882a593Smuzhiyun ncpu = sysconf(_SC_NPROCESSORS_CONF);
22*4882a593Smuzhiyun for (cpu = 0; cpu < ncpu; cpu++) {
23*4882a593Smuzhiyun unsigned long long siblings;
24*4882a593Smuzhiyun char *str;
25*4882a593Smuzhiyun size_t strlen;
26*4882a593Smuzhiyun char fn[256];
27*4882a593Smuzhiyun
28*4882a593Smuzhiyun snprintf(fn, sizeof fn,
29*4882a593Smuzhiyun "devices/system/cpu/cpu%d/topology/core_cpus", cpu);
30*4882a593Smuzhiyun if (sysfs__read_str(fn, &str, &strlen) < 0) {
31*4882a593Smuzhiyun snprintf(fn, sizeof fn,
32*4882a593Smuzhiyun "devices/system/cpu/cpu%d/topology/thread_siblings",
33*4882a593Smuzhiyun cpu);
34*4882a593Smuzhiyun if (sysfs__read_str(fn, &str, &strlen) < 0)
35*4882a593Smuzhiyun continue;
36*4882a593Smuzhiyun }
37*4882a593Smuzhiyun /* Entry is hex, but does not have 0x, so need custom parser */
38*4882a593Smuzhiyun siblings = strtoull(str, NULL, 16);
39*4882a593Smuzhiyun free(str);
40*4882a593Smuzhiyun if (hweight64(siblings) > 1) {
41*4882a593Smuzhiyun cached_result = 1;
42*4882a593Smuzhiyun cached = true;
43*4882a593Smuzhiyun break;
44*4882a593Smuzhiyun }
45*4882a593Smuzhiyun }
46*4882a593Smuzhiyun if (!cached) {
47*4882a593Smuzhiyun cached_result = 0;
48*4882a593Smuzhiyun done:
49*4882a593Smuzhiyun cached = true;
50*4882a593Smuzhiyun }
51*4882a593Smuzhiyun return cached_result;
52*4882a593Smuzhiyun }
53