| // ---------------------------------------------------------------------- |
| // CycleClock |
| // A CycleClock tells you the current time in Cycles. The "time" |
| // is actually time since power-on. This is like time() but doesn't |
| // involve a system call and is much more precise. |
| // |
| // NOTE: Not all cpu/platform/kernel combinations guarantee that this |
| // clock increments at a constant rate or is synchronized across all logical |
| // cpus in a system. |
| // |
| // If you need the above guarantees, please consider using a different |
| // API. There are efforts to provide an interface which provides a millisecond |
| // granularity and implemented as a memory read. A memory read is generally |
| // cheaper than the CycleClock for many architectures. |
| // |
| // Also, in some out of order CPU implementations, the CycleClock is not |
| // serializing. So if you're trying to count at cycles granularity, your |
| // data might be inaccurate due to out of order instruction execution. |
| // ---------------------------------------------------------------------- |
| |
| #ifndef BENCHMARK_CYCLECLOCK_H_ |
| #define BENCHMARK_CYCLECLOCK_H_ |
| |
| #include <cstdint> |
| |
| #include "benchmark/macros.h" |
| #include "internal_macros.h" |
| |
| #if defined(BENCHMARK_OS_MACOSX) |
| #include <mach/mach_time.h> |
| #endif |
| // For MSVC, we want to use '_asm rdtsc' when possible (since it works |
| // with even ancient MSVC compilers), and when not possible the |
| // __rdtsc intrinsic, declared in <intrin.h>. Unfortunately, in some |
| // environments, <windows.h> and <intrin.h> have conflicting |
| // declarations of some other intrinsics, breaking compilation. |
| // Therefore, we simply declare __rdtsc ourselves. See also |
| // http://connect.microsoft.com/VisualStudio/feedback/details/262047 |
| #if defined(COMPILER_MSVC) && !defined(_M_IX86) |
| extern "C" uint64_t __rdtsc(); |
| #pragma intrinsic(__rdtsc) |
| #endif |
| |
| #ifndef BENCHMARK_OS_WINDOWS |
| #include <sys/time.h> |
| #endif |
| |
| namespace benchmark { |
| // NOTE: only i386 and x86_64 have been well tested. |
| // PPC, sparc, alpha, and ia64 are based on |
| // http://peter.kuscsik.com/wordpress/?p=14 |
| // with modifications by m3b. See also |
| // https://setisvn.ssl.berkeley.edu/svn/lib/fftw-3.0.1/kernel/cycle.h |
| namespace cycleclock { |
| // This should return the number of cycles since power-on. Thread-safe. |
| inline BENCHMARK_ALWAYS_INLINE int64_t Now() { |
| #if defined(OS_MACOSX) |
| // this goes at the top because we need ALL Macs, regardless of |
| // architecture, to return the number of "mach time units" that |
| // have passed since startup. See sysinfo.cc where |
| // InitializeSystemInfo() sets the supposed cpu clock frequency of |
| // macs to the number of mach time units per second, not actual |
| // CPU clock frequency (which can change in the face of CPU |
| // frequency scaling). Also note that when the Mac sleeps, this |
| // counter pauses; it does not continue counting, nor does it |
| // reset to zero. |
| return mach_absolute_time(); |
| #elif defined(__i386__) |
| int64_t ret; |
| __asm__ volatile("rdtsc" : "=A"(ret)); |
| return ret; |
| #elif defined(__x86_64__) || defined(__amd64__) |
| uint64_t low, high; |
| __asm__ volatile("rdtsc" : "=a"(low), "=d"(high)); |
| return (high << 32) | low; |
| #elif defined(__powerpc__) || defined(__ppc__) |
| // This returns a time-base, which is not always precisely a cycle-count. |
| int64_t tbl, tbu0, tbu1; |
| asm("mftbu %0" : "=r"(tbu0)); |
| asm("mftb %0" : "=r"(tbl)); |
| asm("mftbu %0" : "=r"(tbu1)); |
| tbl &= -static_cast<int64>(tbu0 == tbu1); |
| // high 32 bits in tbu1; low 32 bits in tbl (tbu0 is garbage) |
| return (tbu1 << 32) | tbl; |
| #elif defined(__sparc__) |
| int64_t tick; |
| asm(".byte 0x83, 0x41, 0x00, 0x00"); |
| asm("mov %%g1, %0" : "=r"(tick)); |
| return tick; |
| #elif defined(__ia64__) |
| int64_t itc; |
| asm("mov %0 = ar.itc" : "=r"(itc)); |
| return itc; |
| #elif defined(COMPILER_MSVC) && defined(_M_IX86) |
| // Older MSVC compilers (like 7.x) don't seem to support the |
| // __rdtsc intrinsic properly, so I prefer to use _asm instead |
| // when I know it will work. Otherwise, I'll use __rdtsc and hope |
| // the code is being compiled with a non-ancient compiler. |
| _asm rdtsc |
| #elif defined(COMPILER_MSVC) |
| return __rdtsc(); |
| #elif defined(__ARM_ARCH) |
| #if (__ARM_ARCH >= 6) // V6 is the earliest arch that has a standard cyclecount |
| uint32_t pmccntr; |
| uint32_t pmuseren; |
| uint32_t pmcntenset; |
| // Read the user mode perf monitor counter access permissions. |
| asm("mrc p15, 0, %0, c9, c14, 0" : "=r"(pmuseren)); |
| if (pmuseren & 1) { // Allows reading perfmon counters for user mode code. |
| asm("mrc p15, 0, %0, c9, c12, 1" : "=r"(pmcntenset)); |
| if (pmcntenset & 0x80000000ul) { // Is it counting? |
| asm("mrc p15, 0, %0, c9, c13, 0" : "=r"(pmccntr)); |
| // The counter is set up to count every 64th cycle |
| return static_cast<int64_t>(pmccntr) * 64; // Should optimize to << 6 |
| } |
| } |
| #endif |
| struct timeval tv; |
| gettimeofday(&tv, nullptr); |
| return static_cast<int64_t>(tv.tv_sec) * 1000000 + tv.tv_usec; |
| #elif defined(__mips__) |
| // mips apparently only allows rdtsc for superusers, so we fall |
| // back to gettimeofday. It's possible clock_gettime would be better. |
| struct timeval tv; |
| gettimeofday(&tv, nullptr); |
| return static_cast<int64_t>(tv.tv_sec) * 1000000 + tv.tv_usec; |
| #else |
| // The soft failover to a generic implementation is automatic only for ARM. |
| // For other platforms the developer is expected to make an attempt to create |
| // a fast implementation and use generic version if nothing better is available. |
| #error You need to define CycleTimer for your OS and CPU |
| #endif |
| } |
| } // end namespace cycleclock |
| } // end namespace benchmark |
| |
| #endif // BENCHMARK_CYCLECLOCK_H_ |