1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
|
// SPDX-License-Identifier: GPL-2.0
#include <linux/types.h>
#include <math.h>
#include <string.h>
#include "../../../util/debug.h"
#include "../../../util/tsc.h"
#include "cpuid.h"
u64 rdtsc(void)
{
unsigned int low, high;
asm volatile("rdtsc" : "=a" (low), "=d" (high));
return low | ((u64)high) << 32;
}
/*
* Derive the TSC frequency in Hz from the /proc/cpuinfo, for example:
* ...
* model name : Intel(R) Xeon(R) Gold 6154 CPU @ 3.00GHz
* ...
* will return 3000000000.
*/
static double cpuinfo_tsc_freq(void)
{
double result = 0;
FILE *cpuinfo;
char *line = NULL;
size_t len = 0;
cpuinfo = fopen("/proc/cpuinfo", "r");
if (!cpuinfo) {
pr_err("Failed to read /proc/cpuinfo for TSC frequency");
return NAN;
}
while (getline(&line, &len, cpuinfo) > 0) {
if (!strncmp(line, "model name", 10)) {
char *pos = strstr(line + 11, " @ ");
if (pos && sscanf(pos, " @ %lfGHz", &result) == 1) {
result *= 1000000000;
goto out;
}
}
}
out:
if (fpclassify(result) == FP_ZERO)
pr_err("Failed to find TSC frequency in /proc/cpuinfo");
free(line);
fclose(cpuinfo);
return result;
}
double arch_get_tsc_freq(void)
{
unsigned int a, b, c, d, lvl;
static bool cached;
static double tsc;
char vendor[16];
if (cached)
return tsc;
cached = true;
get_cpuid_0(vendor, &lvl);
if (!strstr(vendor, "Intel"))
return 0;
/*
* Don't support Time Stamp Counter and
* Nominal Core Crystal Clock Information Leaf.
*/
if (lvl < 0x15) {
tsc = cpuinfo_tsc_freq();
return tsc;
}
cpuid(0x15, 0, &a, &b, &c, &d);
/* TSC frequency is not enumerated */
if (!a || !b || !c) {
tsc = cpuinfo_tsc_freq();
return tsc;
}
tsc = (double)c * (double)b / (double)a;
return tsc;
}
|
