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Diffstat (limited to 'src/base/cycleclock.h')
| -rw-r--r-- | src/base/cycleclock.h | 163 |
1 files changed, 163 insertions, 0 deletions
diff --git a/src/base/cycleclock.h b/src/base/cycleclock.h new file mode 100644 index 0000000..1392fad --- /dev/null +++ b/src/base/cycleclock.h @@ -0,0 +1,163 @@ +// Copyright (c) 2004, Google Inc. +// All rights reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following disclaimer +// in the documentation and/or other materials provided with the +// distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +// ---------------------------------------------------------------------- +// 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. +// +// 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 GOOGLE_BASE_CYCLECLOCK_H_ +#define GOOGLE_BASE_CYCLECLOCK_H_ + +#include "base/basictypes.h" // make sure we get the def for int64 +#include "base/arm_instruction_set_select.h" +// base/sysinfo.h is really big and we don't want to include it unless +// it is necessary. +#if defined(__arm__) || defined(__mips__) +# include "base/sysinfo.h" +#endif +#if defined(__MACH__) && defined(__APPLE__) +# 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(_MSC_VER) && !defined(_M_IX86) +extern "C" uint64 __rdtsc(); +#pragma intrinsic(__rdtsc) +#endif +#ifdef HAVE_SYS_TIME_H +#include <sys/time.h> +#endif + +// 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 +struct CycleClock { + // This should return the number of cycles since power-on. Thread-safe. + static inline int64 Now() { +#if defined(__MACH__) && defined(__APPLE__) + // 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 ret; + __asm__ volatile ("rdtsc" : "=A" (ret) ); + return ret; +#elif defined(__x86_64__) || defined(__amd64__) + uint64 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 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 tick; + asm(".byte 0x83, 0x41, 0x00, 0x00"); + asm("mov %%g1, %0" : "=r" (tick)); + return tick; +#elif defined(__ia64__) + int64 itc; + asm("mov %0 = ar.itc" : "=r" (itc)); + return itc; +#elif defined(_MSC_VER) && 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(_MSC_VER) + return __rdtsc(); +#elif defined (__linux__) //defined(ARMV3) +#if defined(ARMV6) // V6 is the earliest arch that has a standard cyclecount + uint32 pmccntr; + uint32 pmuseren; + uint32 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>(pmccntr) * 64; // Should optimize to << 6 + } + } +#endif + struct timeval tv; + gettimeofday(&tv, NULL); + return static_cast<int64>((tv.tv_sec + tv.tv_usec * 0.000001) + * CyclesPerSecond()); +#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, NULL); + return static_cast<int64>((tv.tv_sec + tv.tv_usec * 0.000001) + * CyclesPerSecond()); +#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 O/S and CPU +#endif + } +}; + + +#endif // GOOGLE_BASE_CYCLECLOCK_H_ |