1 // Copyright (c) 2004, Google Inc. 2 // All rights reserved. 3 // 4 // Redistribution and use in source and binary forms, with or without 5 // modification, are permitted provided that the following conditions are 6 // met: 7 // 8 // * Redistributions of source code must retain the above copyright 9 // notice, this list of conditions and the following disclaimer. 10 // * Redistributions in binary form must reproduce the above 11 // copyright notice, this list of conditions and the following disclaimer 12 // in the documentation and/or other materials provided with the 13 // distribution. 14 // * Neither the name of Google Inc. nor the names of its 15 // contributors may be used to endorse or promote products derived from 16 // this software without specific prior written permission. 17 // 18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 19 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 20 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 21 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 22 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 23 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 24 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 30 // ---------------------------------------------------------------------- 31 // CycleClock 32 // A CycleClock tells you the current time in Cycles. The "time" 33 // is actually time since power-on. This is like time() but doesn't 34 // involve a system call and is much more precise. 35 // 36 // NOTE: Not all cpu/platform/kernel combinations guarantee that this 37 // clock increments at a constant rate or is synchronized across all logical 38 // cpus in a system. 39 // 40 // Also, in some out of order CPU implementations, the CycleClock is not 41 // serializing. So if you're trying to count at cycles granularity, your 42 // data might be inaccurate due to out of order instruction execution. 43 // ---------------------------------------------------------------------- 44 45 #ifndef GOOGLE_BASE_CYCLECLOCK_H_ 46 #define GOOGLE_BASE_CYCLECLOCK_H_ 47 48 #include "base/basictypes.h" // make sure we get the def for int64 49 #include "base/arm_instruction_set_select.h" 50 // base/sysinfo.h is really big and we don't want to include it unless 51 // it is necessary. 52 #if defined(__arm__) || defined(__mips__) 53 # include "base/sysinfo.h" 54 #endif 55 #if defined(__MACH__) && defined(__APPLE__) 56 # include <mach/mach_time.h> 57 #endif 58 // For MSVC, we want to use '_asm rdtsc' when possible (since it works 59 // with even ancient MSVC compilers), and when not possible the 60 // __rdtsc intrinsic, declared in <intrin.h>. Unfortunately, in some 61 // environments, <windows.h> and <intrin.h> have conflicting 62 // declarations of some other intrinsics, breaking compilation. 63 // Therefore, we simply declare __rdtsc ourselves. See also 64 // http://connect.microsoft.com/VisualStudio/feedback/details/262047 65 #if defined(_MSC_VER) && !defined(_M_IX86) 66 extern "C" uint64 __rdtsc(); 67 #pragma intrinsic(__rdtsc) 68 #endif 69 #if defined(ARMV3) || defined(__mips__) 70 #include <sys/time.h> 71 #endif 72 73 // NOTE: only i386 and x86_64 have been well tested. 74 // PPC, sparc, alpha, and ia64 are based on 75 // http://peter.kuscsik.com/wordpress/?p=14 76 // with modifications by m3b. See also 77 // https://setisvn.ssl.berkeley.edu/svn/lib/fftw-3.0.1/kernel/cycle.h 78 struct CycleClock { 79 // This should return the number of cycles since power-on. Thread-safe. 80 static inline int64 Now() { 81 #if defined(__MACH__) && defined(__APPLE__) 82 // this goes at the top because we need ALL Macs, regardless of 83 // architecture, to return the number of "mach time units" that 84 // have passed since startup. See sysinfo.cc where 85 // InitializeSystemInfo() sets the supposed cpu clock frequency of 86 // macs to the number of mach time units per second, not actual 87 // CPU clock frequency (which can change in the face of CPU 88 // frequency scaling). Also note that when the Mac sleeps, this 89 // counter pauses; it does not continue counting, nor does it 90 // reset to zero. 91 return mach_absolute_time(); 92 #elif defined(__i386__) 93 int64 ret; 94 __asm__ volatile ("rdtsc" : "=A" (ret) ); 95 return ret; 96 #elif defined(__x86_64__) || defined(__amd64__) 97 uint64 low, high; 98 __asm__ volatile ("rdtsc" : "=a" (low), "=d" (high)); 99 return (high << 32) | low; 100 #elif defined(__powerpc__) || defined(__ppc__) 101 // This returns a time-base, which is not always precisely a cycle-count. 102 int64 tbl, tbu0, tbu1; 103 asm("mftbu %0" : "=r" (tbu0)); 104 asm("mftb %0" : "=r" (tbl)); 105 asm("mftbu %0" : "=r" (tbu1)); 106 tbl &= -static_cast<int64>(tbu0 == tbu1); 107 // high 32 bits in tbu1; low 32 bits in tbl (tbu0 is garbage) 108 return (tbu1 << 32) | tbl; 109 #elif defined(__sparc__) 110 int64 tick; 111 asm(".byte 0x83, 0x41, 0x00, 0x00"); 112 asm("mov %%g1, %0" : "=r" (tick)); 113 return tick; 114 #elif defined(__ia64__) 115 int64 itc; 116 asm("mov %0 = ar.itc" : "=r" (itc)); 117 return itc; 118 #elif defined(_MSC_VER) && defined(_M_IX86) 119 // Older MSVC compilers (like 7.x) don't seem to support the 120 // __rdtsc intrinsic properly, so I prefer to use _asm instead 121 // when I know it will work. Otherwise, I'll use __rdtsc and hope 122 // the code is being compiled with a non-ancient compiler. 123 _asm rdtsc 124 #elif defined(_MSC_VER) 125 return __rdtsc(); 126 #elif defined(ARMV3) 127 #if defined(ARMV6) // V6 is the earliest arch that has a standard cyclecount 128 uint32 pmccntr; 129 uint32 pmuseren; 130 uint32 pmcntenset; 131 // Read the user mode perf monitor counter access permissions. 132 asm volatile ("mrc p15, 0, %0, c9, c14, 0" : "=r" (pmuseren)); 133 if (pmuseren & 1) { // Allows reading perfmon counters for user mode code. 134 asm volatile ("mrc p15, 0, %0, c9, c12, 1" : "=r" (pmcntenset)); 135 if (pmcntenset & 0x80000000ul) { // Is it counting? 136 asm volatile ("mrc p15, 0, %0, c9, c13, 0" : "=r" (pmccntr)); 137 // The counter is set up to count every 64th cycle 138 return static_cast<int64>(pmccntr) * 64; // Should optimize to << 6 139 } 140 } 141 #endif 142 struct timeval tv; 143 gettimeofday(&tv, NULL); 144 return static_cast<int64>((tv.tv_sec + tv.tv_usec * 0.000001) 145 * CyclesPerSecond()); 146 #elif defined(__mips__) 147 // mips apparently only allows rdtsc for superusers, so we fall 148 // back to gettimeofday. It's possible clock_gettime would be better. 149 struct timeval tv; 150 gettimeofday(&tv, NULL); 151 return static_cast<int64>((tv.tv_sec + tv.tv_usec * 0.000001) 152 * CyclesPerSecond()); 153 #else 154 // The soft failover to a generic implementation is automatic only for ARM. 155 // For other platforms the developer is expected to make an attempt to create 156 // a fast implementation and use generic version if nothing better is available. 157 #error You need to define CycleTimer for your O/S and CPU 158 #endif 159 } 160 }; 161 162 163 #endif // GOOGLE_BASE_CYCLECLOCK_H_ 164
