nacl/cpucycles/amd64cpuspeed.c


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#include <stdio.h>
#include <sys/types.h>
#include <sys/param.h>
#include <sys/sysctl.h>

long long cpucycles_amd64cpuspeed(void)
{
  unsigned long long result;
  asm volatile(".byte 15;.byte 49;shlq $32,%%rdx;orq %%rdx,%%rax"
    : "=a" (result) ::  "%rdx");
  return result;
}

long long cpucycles_amd64cpuspeed_persecond(void)
{
  int oid[2];
  int val;
  size_t size;
  oid[0] = CTL_HW;
  oid[1] = HW_CPUSPEED;
  size = sizeof val;
  if (sysctl(oid,2,&val,&size,0,0) == -1) return 0;
  if (size != sizeof val) return 0;
  return val * 1000000LL;
}