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Add hyper-threading detection

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Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2010-03-14 12:14:09 +01:00
parent 92bada1a32
commit c853b87c08
1 changed files with 52 additions and 5 deletions
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57
src/misc.cpp
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@ -41,6 +41,7 @@
#include <cassert> #include <cassert>
#include <cstdio> #include <cstdio>
#include <cstring>
#include <iomanip> #include <iomanip>
#include <iostream> #include <iostream>
#include <sstream> #include <sstream>
@ -182,16 +183,17 @@ int get_system_time() {
} }
/// cpu_count() tries to detect the number of CPU cores. /// builtin_cpu_count() tries to detect the number of CPU cores, if
/// hyper-threading is enabled this is the number of logical processors.
#if !defined(_MSC_VER) #if !defined(_MSC_VER)
# if defined(_SC_NPROCESSORS_ONLN) # if defined(_SC_NPROCESSORS_ONLN)
int cpu_count() { static int builtin_cpu_count() {
return Min(sysconf(_SC_NPROCESSORS_ONLN), 8); return Min(sysconf(_SC_NPROCESSORS_ONLN), 8);
} }
# elif defined(__hpux) # elif defined(__hpux)
int cpu_count() { static int builtin_cpu_count() {
struct pst_dynamic psd; struct pst_dynamic psd;
if (pstat_getdynamic(&psd, sizeof(psd), (size_t)1, 0) == -1) if (pstat_getdynamic(&psd, sizeof(psd), (size_t)1, 0) == -1)
return 1; return 1;
@ -199,14 +201,14 @@ int cpu_count() {
return Min(psd.psd_proc_cnt, 8); return Min(psd.psd_proc_cnt, 8);
} }
# else # else
int cpu_count() { static int builtin_cpu_count() {
return 1; return 1;
} }
# endif # endif
#else #else
int cpu_count() { static int builtin_cpu_count() {
SYSTEM_INFO s; SYSTEM_INFO s;
GetSystemInfo(&s); GetSystemInfo(&s);
return Min(s.dwNumberOfProcessors, 8); return Min(s.dwNumberOfProcessors, 8);
@ -215,6 +217,51 @@ int cpu_count() {
#endif #endif
/// HT_enabled() returns true if hyper-threading is enabled on current machine
static bool HT_enabled() {
char CPUString[0x20];
int CPUInfo[4] = {-1};
int nIds, nLogicalCPU, nCores;
// Detect CPU producer
__cpuid(CPUInfo, 0);
nIds = CPUInfo[0];
memset(CPUString, 0, sizeof(CPUString));
*((int*)(CPUString+0)) = CPUInfo[1];
*((int*)(CPUString+4)) = CPUInfo[3];
*((int*)(CPUString+8)) = CPUInfo[2];
// Not an Intel CPU or CPUID.4 not supported
if (strcmp(CPUString, "GenuineIntel") || nIds < 4)
return false;
// Detect if HT Technology is supported
__cpuid(CPUInfo, 1);
if (!((CPUInfo[3] >> 28) & 1))
return false;
nLogicalCPU = (CPUInfo[1] >> 16) & 0xFF;
// Detect number of cores
__cpuid(CPUInfo, 4);
nCores = 1 + ((CPUInfo[0] >> 26) & 0x3F);
return nLogicalCPU > nCores;
}
/// cpu_count() tries to detect the number of physical CPU cores taking
/// in account hyper-threading.
int cpu_count() {
return HT_enabled() ? builtin_cpu_count() / 2 : builtin_cpu_count();
}
/* /*
From Beowulf, from Olithink From Beowulf, from Olithink
*/ */