--- /dev/null
+// ----------------------------------------------------------------------
+// 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/benchmark.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) && !defined(_M_ARM64)
+extern "C" uint64_t __rdtsc();
+#pragma intrinsic(__rdtsc)
+#endif
+
+#if !defined(BENCHMARK_OS_WINDOWS) || defined(BENCHMARK_OS_MINGW)
+#include <sys/time.h>
+#include <time.h>
+#endif
+
+#ifdef BENCHMARK_OS_EMSCRIPTEN
+#include <emscripten.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(BENCHMARK_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(BENCHMARK_OS_EMSCRIPTEN)
+ // this goes above x86-specific code because old versions of Emscripten
+ // define __x86_64__, although they have nothing to do with it.
+ return static_cast<int64_t>(emscripten_get_now() * 1e+6);
+#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.
+#if defined(__powerpc64__) || defined(__ppc64__)
+ int64_t tb;
+ asm volatile("mfspr %0, 268" : "=r"(tb));
+ return tb;
+#else
+ uint32_t tbl, tbu0, tbu1;
+ asm volatile(
+ "mftbu %0\n"
+ "mftb %1\n"
+ "mftbu %2"
+ : "=r"(tbu0), "=r"(tbl), "=r"(tbu1));
+ tbl &= -static_cast<int32_t>(tbu0 == tbu1);
+ // high 32 bits in tbu1; low 32 bits in tbl (tbu0 is no longer needed)
+ return (static_cast<uint64_t>(tbu1) << 32) | tbl;
+#endif
+#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) && defined(_M_ARM64)
+ // See https://docs.microsoft.com/en-us/cpp/intrinsics/arm64-intrinsics?view=vs-2019
+ // and https://reviews.llvm.org/D53115
+ int64_t virtual_timer_value;
+ virtual_timer_value = _ReadStatusReg(ARM64_CNTVCT);
+ return virtual_timer_value;
+#elif defined(COMPILER_MSVC)
+ return __rdtsc();
+#elif defined(BENCHMARK_OS_NACL)
+ // Native Client validator on x86/x86-64 allows RDTSC instructions,
+ // and this case is handled above. Native Client validator on ARM
+ // rejects MRC instructions (used in the ARM-specific sequence below),
+ // so we handle it here. Portable Native Client compiles to
+ // architecture-agnostic bytecode, which doesn't provide any
+ // cycle counter access mnemonics.
+
+ // Native Client does not provide any API to access cycle counter.
+ // Use clock_gettime(CLOCK_MONOTONIC, ...) instead of gettimeofday
+ // because is provides nanosecond resolution (which is noticable at
+ // least for PNaCl modules running on x86 Mac & Linux).
+ // Initialize to always return 0 if clock_gettime fails.
+ struct timespec ts = {0, 0};
+ clock_gettime(CLOCK_MONOTONIC, &ts);
+ return static_cast<int64_t>(ts.tv_sec) * 1000000000 + ts.tv_nsec;
+#elif defined(__aarch64__)
+ // System timer of ARMv8 runs at a different frequency than the CPU's.
+ // The frequency is fixed, typically in the range 1-50MHz. It can be
+ // read at CNTFRQ special register. We assume the OS has set up
+ // the virtual timer properly.
+ int64_t virtual_timer_value;
+ asm volatile("mrs %0, cntvct_el0" : "=r"(virtual_timer_value));
+ return virtual_timer_value;
+#elif defined(__ARM_ARCH)
+ // V6 is the earliest arch that has a standard cyclecount
+ // Native Client validator doesn't allow MRC instructions.
+#if (__ARM_ARCH >= 6)
+ uint32_t pmccntr;
+ uint32_t pmuseren;
+ uint32_t pmcntenset;
+ // Read the user mode perf monitor counter access permissions.
+ asm volatile("mrc p15, 0, %0, c9, c14, 0" : "=r"(pmuseren));
+ if (pmuseren & 1) { // Allows reading perfmon counters for user mode code.
+ asm volatile("mrc p15, 0, %0, c9, c12, 1" : "=r"(pmcntenset));
+ if (pmcntenset & 0x80000000ul) { // Is it counting?
+ asm volatile("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__) || defined(__m68k__)
+ // 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;
+#elif defined(__s390__) // Covers both s390 and s390x.
+ // Return the CPU clock.
+ uint64_t tsc;
+#if defined(BENCHMARK_OS_ZOS) && defined(COMPILER_IBMXL)
+ // z/OS XL compiler HLASM syntax.
+ asm(" stck %0" : "=m"(tsc) : : "cc");
+#else
+ asm("stck %0" : "=Q"(tsc) : : "cc");
+#endif
+ return tsc;
+#elif defined(__riscv) // RISC-V
+ // Use RDCYCLE (and RDCYCLEH on riscv32)
+#if __riscv_xlen == 32
+ uint32_t cycles_lo, cycles_hi0, cycles_hi1;
+ // This asm also includes the PowerPC overflow handling strategy, as above.
+ // Implemented in assembly because Clang insisted on branching.
+ asm volatile(
+ "rdcycleh %0\n"
+ "rdcycle %1\n"
+ "rdcycleh %2\n"
+ "sub %0, %0, %2\n"
+ "seqz %0, %0\n"
+ "sub %0, zero, %0\n"
+ "and %1, %1, %0\n"
+ : "=r"(cycles_hi0), "=r"(cycles_lo), "=r"(cycles_hi1));
+ return (static_cast<uint64_t>(cycles_hi1) << 32) | cycles_lo;
+#else
+ uint64_t cycles;
+ asm volatile("rdcycle %0" : "=r"(cycles));
+ return cycles;
+#endif
+#elif defined(__e2k__) || defined(__elbrus__)
+ 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_
projects / ceph.git / blobdiff