x86: AVX-512 support
[x264/x264-sandbox.git] / common / cpu.c
index 1de9fb1..8638186 100644 (file)
@@ -1,10 +1,11 @@
 /*****************************************************************************
- * cpu.c: h264 encoder library
+ * cpu.c: cpu detection
  *****************************************************************************
- * Copyright (C) 2003 Laurent Aimar
- * $Id: cpu.c,v 1.1 2004/06/03 19:27:06 fenrir Exp $
+ * Copyright (C) 2003-2017 x264 project
  *
- * Authors: Laurent Aimar <fenrir@via.ecp.fr>
+ * Authors: Loren Merritt <lorenm@u.washington.edu>
+ *          Laurent Aimar <fenrir@via.ecp.fr>
+ *          Fiona Glaser <fiona@x264.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02111, USA.
+ *
+ * This program is also available under a commercial proprietary license.
+ * For more information, contact us at licensing@x264.com.
  *****************************************************************************/
 
-#if defined(HAVE_PTHREAD) && defined(SYS_LINUX)
-#define _GNU_SOURCE
+#include "common.h"
+
+#if HAVE_POSIXTHREAD && SYS_LINUX
 #include <sched.h>
 #endif
-#ifdef SYS_BEOS
+#if SYS_BEOS
 #include <kernel/OS.h>
 #endif
-#if defined(SYS_MACOSX) || defined(SYS_FREEBSD)
+#if SYS_MACOSX || SYS_FREEBSD
 #include <sys/types.h>
 #include <sys/sysctl.h>
 #endif
+#if SYS_OPENBSD
+#include <sys/param.h>
+#include <sys/sysctl.h>
+#include <machine/cpu.h>
+#endif
 
-#include "common.h"
+const x264_cpu_name_t x264_cpu_names[] =
+{
+#if HAVE_MMX
+//  {"MMX",         X264_CPU_MMX},  // we don't support asm on mmx1 cpus anymore
+#define MMX2 X264_CPU_MMX|X264_CPU_MMX2
+    {"MMX2",        MMX2},
+    {"MMXEXT",      MMX2},
+    {"SSE",         MMX2|X264_CPU_SSE},
+#define SSE2 MMX2|X264_CPU_SSE|X264_CPU_SSE2
+    {"SSE2Slow",    SSE2|X264_CPU_SSE2_IS_SLOW},
+    {"SSE2",        SSE2},
+    {"SSE2Fast",    SSE2|X264_CPU_SSE2_IS_FAST},
+    {"LZCNT",       SSE2|X264_CPU_LZCNT},
+    {"SSE3",        SSE2|X264_CPU_SSE3},
+    {"SSSE3",       SSE2|X264_CPU_SSE3|X264_CPU_SSSE3},
+    {"SSE4.1",      SSE2|X264_CPU_SSE3|X264_CPU_SSSE3|X264_CPU_SSE4},
+    {"SSE4",        SSE2|X264_CPU_SSE3|X264_CPU_SSSE3|X264_CPU_SSE4},
+    {"SSE4.2",      SSE2|X264_CPU_SSE3|X264_CPU_SSSE3|X264_CPU_SSE4|X264_CPU_SSE42},
+#define AVX SSE2|X264_CPU_SSE3|X264_CPU_SSSE3|X264_CPU_SSE4|X264_CPU_SSE42|X264_CPU_AVX
+    {"AVX",         AVX},
+    {"XOP",         AVX|X264_CPU_XOP},
+    {"FMA4",        AVX|X264_CPU_FMA4},
+    {"FMA3",        AVX|X264_CPU_FMA3},
+    {"BMI1",        AVX|X264_CPU_LZCNT|X264_CPU_BMI1},
+    {"BMI2",        AVX|X264_CPU_LZCNT|X264_CPU_BMI1|X264_CPU_BMI2},
+#define AVX2 AVX|X264_CPU_FMA3|X264_CPU_LZCNT|X264_CPU_BMI1|X264_CPU_BMI2|X264_CPU_AVX2
+    {"AVX2",        AVX2},
+    {"AVX512",      AVX2|X264_CPU_AVX512},
+#undef AVX2
+#undef AVX
+#undef SSE2
+#undef MMX2
+    {"Cache32",         X264_CPU_CACHELINE_32},
+    {"Cache64",         X264_CPU_CACHELINE_64},
+    {"SlowAtom",        X264_CPU_SLOW_ATOM},
+    {"SlowPshufb",      X264_CPU_SLOW_PSHUFB},
+    {"SlowPalignr",     X264_CPU_SLOW_PALIGNR},
+    {"SlowShuffle",     X264_CPU_SLOW_SHUFFLE},
+    {"UnalignedStack",  X264_CPU_STACK_MOD4},
+#elif ARCH_PPC
+    {"Altivec",         X264_CPU_ALTIVEC},
+#elif ARCH_ARM
+    {"ARMv6",           X264_CPU_ARMV6},
+    {"NEON",            X264_CPU_NEON},
+    {"FastNeonMRC",     X264_CPU_FAST_NEON_MRC},
+#elif ARCH_AARCH64
+    {"ARMv8",           X264_CPU_ARMV8},
+    {"NEON",            X264_CPU_NEON},
+#elif ARCH_MIPS
+    {"MSA",             X264_CPU_MSA},
+#endif
+    {"", 0},
+};
 
-#ifdef HAVE_MMX
-extern int  x264_cpu_cpuid_test( void );
-extern uint32_t  x264_cpu_cpuid( uint32_t op, uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx );
-extern void x264_emms( void );
+#if (ARCH_PPC && SYS_LINUX) || (ARCH_ARM && !HAVE_NEON)
+#include <signal.h>
+#include <setjmp.h>
+static sigjmp_buf jmpbuf;
+static volatile sig_atomic_t canjump = 0;
+
+static void sigill_handler( int sig )
+{
+    if( !canjump )
+    {
+        signal( sig, SIG_DFL );
+        raise( sig );
+    }
+
+    canjump = 0;
+    siglongjmp( jmpbuf, 1 );
+}
+#endif
+
+#if HAVE_MMX
+int x264_cpu_cpuid_test( void );
+void x264_cpu_cpuid( uint32_t op, uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx );
+uint64_t x264_cpu_xgetbv( int xcr );
 
 uint32_t x264_cpu_detect( void )
 {
     uint32_t cpu = 0;
     uint32_t eax, ebx, ecx, edx;
     uint32_t vendor[4] = {0};
-    int max_extended_cap;
-    int cache;
+    uint32_t max_extended_cap, max_basic_cap;
+    uint64_t xcr0 = 0;
 
+#if !ARCH_X86_64
     if( !x264_cpu_cpuid_test() )
         return 0;
+#endif
 
-    x264_cpu_cpuid( 0, &eax, vendor+0, vendor+2, vendor+1 );
-    if( eax == 0 )
+    x264_cpu_cpuid( 0, &max_basic_cap, vendor+0, vendor+2, vendor+1 );
+    if( max_basic_cap == 0 )
         return 0;
 
     x264_cpu_cpuid( 1, &eax, &ebx, &ecx, &edx );
     if( edx&0x00800000 )
         cpu |= X264_CPU_MMX;
     else
-        return 0;
+        return cpu;
     if( edx&0x02000000 )
-        cpu |= X264_CPU_MMXEXT|X264_CPU_SSE;
+        cpu |= X264_CPU_MMX2|X264_CPU_SSE;
     if( edx&0x04000000 )
         cpu |= X264_CPU_SSE2;
-#ifdef HAVE_SSE3
     if( ecx&0x00000001 )
         cpu |= X264_CPU_SSE3;
     if( ecx&0x00000200 )
-        cpu |= X264_CPU_SSSE3;
-#endif
+        cpu |= X264_CPU_SSSE3|X264_CPU_SSE2_IS_FAST;
+    if( ecx&0x00080000 )
+        cpu |= X264_CPU_SSE4;
+    if( ecx&0x00100000 )
+        cpu |= X264_CPU_SSE42;
+
+    if( ecx&0x08000000 ) /* XGETBV supported and XSAVE enabled by OS */
+    {
+        xcr0 = x264_cpu_xgetbv( 0 );
+        if( (xcr0&0x6) == 0x6 ) /* XMM/YMM state */
+        {
+            if( ecx&0x10000000 )
+                cpu |= X264_CPU_AVX;
+            if( ecx&0x00001000 )
+                cpu |= X264_CPU_FMA3;
+        }
+    }
+
+    if( max_basic_cap >= 7 )
+    {
+        x264_cpu_cpuid( 7, &eax, &ebx, &ecx, &edx );
+
+        if( ebx&0x00000008 )
+            cpu |= X264_CPU_BMI1;
+        if( ebx&0x00000100 )
+            cpu |= X264_CPU_BMI2;
+
+        if( (xcr0&0x6) == 0x6 ) /* XMM/YMM state */
+        {
+            if( ebx&0x00000020 )
+                cpu |= X264_CPU_AVX2;
+
+            if( (xcr0&0xE0) == 0xE0 ) /* OPMASK/ZMM state */
+            {
+                if( (ebx&0xD0030000) == 0xD0030000 )
+                    cpu |= X264_CPU_AVX512;
+            }
+        }
+    }
 
     x264_cpu_cpuid( 0x80000000, &eax, &ebx, &ecx, &edx );
     max_extended_cap = eax;
 
-    if( !strcmp((char*)vendor, "AuthenticAMD") && max_extended_cap >= 0x80000001 )
+    if( max_extended_cap >= 0x80000001 )
     {
         x264_cpu_cpuid( 0x80000001, &eax, &ebx, &ecx, &edx );
-        if( edx&0x80000000 )
-            cpu |= X264_CPU_3DNOW;
-        if( edx&0x00400000 )
-            cpu |= X264_CPU_MMXEXT;
+
+        if( ecx&0x00000020 )
+            cpu |= X264_CPU_LZCNT;             /* Supported by Intel chips starting with Haswell */
+        if( ecx&0x00000040 ) /* SSE4a, AMD only */
+        {
+            int family = ((eax>>8)&0xf) + ((eax>>20)&0xff);
+            cpu |= X264_CPU_SSE2_IS_FAST;      /* Phenom and later CPUs have fast SSE units */
+            if( family == 0x14 )
+            {
+                cpu &= ~X264_CPU_SSE2_IS_FAST; /* SSSE3 doesn't imply fast SSE anymore... */
+                cpu |= X264_CPU_SSE2_IS_SLOW;  /* Bobcat has 64-bit SIMD units */
+                cpu |= X264_CPU_SLOW_PALIGNR;  /* palignr is insanely slow on Bobcat */
+            }
+            if( family == 0x16 )
+            {
+                cpu |= X264_CPU_SLOW_PSHUFB;   /* Jaguar's pshufb isn't that slow, but it's slow enough
+                                                * compared to alternate instruction sequences that this
+                                                * is equal or faster on almost all such functions. */
+            }
+        }
+
+        if( cpu & X264_CPU_AVX )
+        {
+            if( ecx&0x00000800 ) /* XOP */
+                cpu |= X264_CPU_XOP;
+            if( ecx&0x00010000 ) /* FMA4 */
+                cpu |= X264_CPU_FMA4;
+        }
+
+        if( !strcmp((char*)vendor, "AuthenticAMD") )
+        {
+            if( edx&0x00400000 )
+                cpu |= X264_CPU_MMX2;
+            if( (cpu&X264_CPU_SSE2) && !(cpu&X264_CPU_SSE2_IS_FAST) )
+                cpu |= X264_CPU_SSE2_IS_SLOW; /* AMD CPUs come in two types: terrible at SSE and great at it */
+        }
     }
 
-    if( !strcmp((char*)vendor, "GenuineIntel") || !strcmp((char*)vendor, "CyrixInstead") )
-        cpu |= X264_CPU_CACHELINE_SPLIT;
-    /* cacheline size is specified in 3 places, any of which may be missing */
-    x264_cpu_cpuid( 1, &eax, &ebx, &ecx, &edx );
-    cache = (ebx&0xff00)>>5; // cflush size
-    if( !cache && max_extended_cap >= 0x80000006 )
+    if( !strcmp((char*)vendor, "GenuineIntel") )
     {
-        x264_cpu_cpuid( 0x80000006, &eax, &ebx, &ecx, &edx );
-        cache = ecx&0xff; // cacheline size
+        x264_cpu_cpuid( 1, &eax, &ebx, &ecx, &edx );
+        int family = ((eax>>8)&0xf) + ((eax>>20)&0xff);
+        int model  = ((eax>>4)&0xf) + ((eax>>12)&0xf0);
+        if( family == 6 )
+        {
+            /* 6/9 (pentium-m "banias"), 6/13 (pentium-m "dothan"), and 6/14 (core1 "yonah")
+             * theoretically support sse2, but it's significantly slower than mmx for
+             * almost all of x264's functions, so let's just pretend they don't. */
+            if( model == 9 || model == 13 || model == 14 )
+            {
+                cpu &= ~(X264_CPU_SSE2|X264_CPU_SSE3);
+                assert(!(cpu&(X264_CPU_SSSE3|X264_CPU_SSE4)));
+            }
+            /* Detect Atom CPU */
+            else if( model == 28 )
+            {
+                cpu |= X264_CPU_SLOW_ATOM;
+                cpu |= X264_CPU_SLOW_PSHUFB;
+            }
+            /* Conroe has a slow shuffle unit. Check the model number to make sure not
+             * to include crippled low-end Penryns and Nehalems that don't have SSE4. */
+            else if( (cpu&X264_CPU_SSSE3) && !(cpu&X264_CPU_SSE4) && model < 23 )
+                cpu |= X264_CPU_SLOW_SHUFFLE;
+        }
     }
-    if( !cache )
+
+    if( (!strcmp((char*)vendor, "GenuineIntel") || !strcmp((char*)vendor, "CyrixInstead")) && !(cpu&X264_CPU_SSE42))
     {
-        // Cache and TLB Information
-        static const char cache32_ids[] = { 0x0a, 0x0c, 0x41, 0x42, 0x43, 0x44, 0x45, 0x82, 0x83, 0x84, 0x85, 0 };
-        static const char cache64_ids[] = { 0x22, 0x23, 0x25, 0x29, 0x2c, 0x46, 0x47, 0x49, 0x60, 0x66, 0x67, 0x68, 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7c, 0x7f, 0x86, 0x87, 0 };
-        uint32_t buf[4];
-        int max, i=0, j;
-        do {
-            x264_cpu_cpuid( 2, buf+0, buf+1, buf+2, buf+3 );
-            max = buf[0]&0xff;
-            buf[0] &= ~0xff;
-            for(j=0; j<4; j++)
-                if( !(buf[j]>>31) )
-                    while( buf[j] )
-                    {
-                        if( strchr( cache32_ids, buf[j]&0xff ) )
-                            cache = 32;
-                        if( strchr( cache64_ids, buf[j]&0xff ) )
-                            cache = 64;
-                        buf[j] >>= 8;
-                    }
-        } while( ++i < max );
+        /* cacheline size is specified in 3 places, any of which may be missing */
+        x264_cpu_cpuid( 1, &eax, &ebx, &ecx, &edx );
+        int cache = (ebx&0xff00)>>5; // cflush size
+        if( !cache && max_extended_cap >= 0x80000006 )
+        {
+            x264_cpu_cpuid( 0x80000006, &eax, &ebx, &ecx, &edx );
+            cache = ecx&0xff; // cacheline size
+        }
+        if( !cache && max_basic_cap >= 2 )
+        {
+            // Cache and TLB Information
+            static const char cache32_ids[] = { 0x0a, 0x0c, 0x41, 0x42, 0x43, 0x44, 0x45, 0x82, 0x83, 0x84, 0x85, 0 };
+            static const char cache64_ids[] = { 0x22, 0x23, 0x25, 0x29, 0x2c, 0x46, 0x47, 0x49, 0x60, 0x66, 0x67,
+                                                0x68, 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7c, 0x7f, 0x86, 0x87, 0 };
+            uint32_t buf[4];
+            int max, i = 0;
+            do {
+                x264_cpu_cpuid( 2, buf+0, buf+1, buf+2, buf+3 );
+                max = buf[0]&0xff;
+                buf[0] &= ~0xff;
+                for( int j = 0; j < 4; j++ )
+                    if( !(buf[j]>>31) )
+                        while( buf[j] )
+                        {
+                            if( strchr( cache32_ids, buf[j]&0xff ) )
+                                cache = 32;
+                            if( strchr( cache64_ids, buf[j]&0xff ) )
+                                cache = 64;
+                            buf[j] >>= 8;
+                        }
+            } while( ++i < max );
+        }
+
+        if( cache == 32 )
+            cpu |= X264_CPU_CACHELINE_32;
+        else if( cache == 64 )
+            cpu |= X264_CPU_CACHELINE_64;
+        else
+            x264_log( NULL, X264_LOG_WARNING, "unable to determine cacheline size\n" );
     }
 
-    if( cache == 32 )
-        cpu |= X264_CPU_CACHELINE_32;
-    if( cache == 64 )
-        cpu |= X264_CPU_CACHELINE_64;
+#if STACK_ALIGNMENT < 16
+    cpu |= X264_CPU_STACK_MOD4;
+#endif
 
     return cpu;
 }
 
-void     x264_cpu_restore( uint32_t cpu )
-{
-    if( cpu&(X264_CPU_MMX|X264_CPU_MMXEXT|X264_CPU_3DNOW|X264_CPU_3DNOWEXT) )
-    {
-        x264_emms();
-    }
-}
+#elif ARCH_PPC && HAVE_ALTIVEC
 
-#elif defined( ARCH_PPC )
-
-#ifdef SYS_MACOSX
+#if SYS_MACOSX || SYS_OPENBSD || SYS_FREEBSD
 #include <sys/sysctl.h>
 uint32_t x264_cpu_detect( void )
 {
     /* Thank you VLC */
     uint32_t cpu = 0;
+#if SYS_OPENBSD
+    int      selectors[2] = { CTL_MACHDEP, CPU_ALTIVEC };
+#elif SYS_MACOSX
     int      selectors[2] = { CTL_HW, HW_VECTORUNIT };
+#endif
     int      has_altivec = 0;
     size_t   length = sizeof( has_altivec );
+#if SYS_MACOSX || SYS_OPENBSD
     int      error = sysctl( selectors, 2, &has_altivec, &length, NULL, 0 );
+#else
+    int      error = sysctlbyname( "hw.altivec", &has_altivec, &length, NULL, 0 );
+#endif
 
     if( error == 0 && has_altivec != 0 )
-    {
         cpu |= X264_CPU_ALTIVEC;
-    }
 
     return cpu;
 }
 
-#elif defined( SYS_LINUX )
-#include <signal.h>
-#include <setjmp.h>
-static sigjmp_buf jmpbuf;
-static volatile sig_atomic_t canjump = 0;
-
-static void sigill_handler( int sig )
-{
-    if( !canjump )
-    {
-        signal( sig, SIG_DFL );
-        raise( sig );
-    }
-
-    canjump = 0;
-    siglongjmp( jmpbuf, 1 );
-}
+#elif SYS_LINUX
 
 uint32_t x264_cpu_detect( void )
 {
-    static void (* oldsig)( int );
+#ifdef __NO_FPRS__
+    return 0;
+#else
+    static void (*oldsig)( int );
 
     oldsig = signal( SIGILL, sigill_handler );
     if( sigsetjmp( jmpbuf, 1 ) )
@@ -193,58 +365,130 @@ uint32_t x264_cpu_detect( void )
     signal( SIGILL, oldsig );
 
     return X264_CPU_ALTIVEC;
+#endif
 }
 #endif
 
-void     x264_cpu_restore( uint32_t cpu )
+#elif ARCH_ARM
+
+void x264_cpu_neon_test( void );
+int x264_cpu_fast_neon_mrc_test( void );
+
+uint32_t x264_cpu_detect( void )
 {
+    int flags = 0;
+#if HAVE_ARMV6
+    flags |= X264_CPU_ARMV6;
+
+    // don't do this hack if compiled with -mfpu=neon
+#if !HAVE_NEON
+    static void (* oldsig)( int );
+    oldsig = signal( SIGILL, sigill_handler );
+    if( sigsetjmp( jmpbuf, 1 ) )
+    {
+        signal( SIGILL, oldsig );
+        return flags;
+    }
+
+    canjump = 1;
+    x264_cpu_neon_test();
+    canjump = 0;
+    signal( SIGILL, oldsig );
+#endif
+
+    flags |= X264_CPU_NEON;
+
+    // fast neon -> arm (Cortex-A9) detection relies on user access to the
+    // cycle counter; this assumes ARMv7 performance counters.
+    // NEON requires at least ARMv7, ARMv8 may require changes here, but
+    // hopefully this hacky detection method will have been replaced by then.
+    // Note that there is potential for a race condition if another program or
+    // x264 instance disables or reinits the counters while x264 is using them,
+    // which may result in incorrect detection and the counters stuck enabled.
+    // right now Apple does not seem to support performance counters for this test
+#ifndef __MACH__
+    flags |= x264_cpu_fast_neon_mrc_test() ? X264_CPU_FAST_NEON_MRC : 0;
+#endif
+    // TODO: write dual issue test? currently it's A8 (dual issue) vs. A9 (fast mrc)
+#endif
+    return flags;
 }
 
-#else
+#elif ARCH_AARCH64
 
 uint32_t x264_cpu_detect( void )
 {
-    return 0;
+    return X264_CPU_ARMV8 | X264_CPU_NEON;
 }
 
-void     x264_cpu_restore( uint32_t cpu )
+#elif ARCH_MIPS
+
+uint32_t x264_cpu_detect( void )
 {
+    uint32_t flags = 0;
+#if HAVE_MSA
+    flags |= X264_CPU_MSA;
+#endif
+    return flags;
 }
 
-#endif
+#else
 
+uint32_t x264_cpu_detect( void )
+{
+    return 0;
+}
+
+#endif
 
 int x264_cpu_num_processors( void )
 {
-#if !defined(HAVE_PTHREAD)
+#if !HAVE_THREAD
     return 1;
 
-#elif defined(_WIN32)
-    return pthread_num_processors_np();
+#elif SYS_WINDOWS
+    return x264_pthread_num_processors_np();
+
+#elif SYS_CYGWIN || SYS_SunOS
+    return sysconf( _SC_NPROCESSORS_ONLN );
 
-#elif defined(SYS_LINUX)
-    unsigned int bit;
-    int np;
+#elif SYS_LINUX
+#ifdef __ANDROID__
+    // Android NDK does not expose sched_getaffinity
+    return sysconf( _SC_NPROCESSORS_CONF );
+#else
     cpu_set_t p_aff;
     memset( &p_aff, 0, sizeof(p_aff) );
-    sched_getaffinity( 0, sizeof(p_aff), &p_aff );
-    for( np = 0, bit = 0; bit < sizeof(p_aff); bit++ )
+    if( sched_getaffinity( 0, sizeof(p_aff), &p_aff ) )
+        return 1;
+#if HAVE_CPU_COUNT
+    return CPU_COUNT(&p_aff);
+#else
+    int np = 0;
+    for( unsigned int bit = 0; bit < 8 * sizeof(p_aff); bit++ )
         np += (((uint8_t *)&p_aff)[bit / 8] >> (bit % 8)) & 1;
     return np;
+#endif
+#endif
 
-#elif defined(SYS_BEOS)
+#elif SYS_BEOS
     system_info info;
     get_system_info( &info );
     return info.cpu_count;
 
-#elif defined(SYS_MACOSX) || defined(SYS_FREEBSD)
-    int numberOfCPUs;
-    size_t length = sizeof( numberOfCPUs );
-    if( sysctlbyname("hw.ncpu", &numberOfCPUs, &length, NULL, 0) )
+#elif SYS_MACOSX || SYS_FREEBSD || SYS_OPENBSD
+    int ncpu;
+    size_t length = sizeof( ncpu );
+#if SYS_OPENBSD
+    int mib[2] = { CTL_HW, HW_NCPU };
+    if( sysctl(mib, 2, &ncpu, &length, NULL, 0) )
+#else
+    if( sysctlbyname("hw.ncpu", &ncpu, &length, NULL, 0) )
+#endif
     {
-        numberOfCPUs = 1;
+        ncpu = 1;
     }
-    return numberOfCPUs;
+    return ncpu;
 
 #else
     return 1;