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#include <unistd.h>
#include <stdio.h>
// cpucycles_amd64cpuinfo
long long cpucycles(void)
{
unsigned long long result;
asm volatile(".byte 15;.byte 49;shlq $32,%%rdx;orq %%rdx,%%rax"
: "=a" (result) :: "%rdx");
return result;
}
static const long long usecs = 100*1000;
int main() {
long long t0 = cpucycles();
usleep(usecs);
long long t1 = cpucycles();
const long long tsc_hz = ((t1-t0)*1000*1000)/usecs;
const long long tsc_mhz = tsc_hz / 1000 / 1000;
const long long tsc_ghz = tsc_mhz / 1000;
printf("%1lli.%02lli\n", tsc_ghz, (tsc_mhz - 1000*tsc_ghz + 5)/10);
}
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