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

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