diff options
Diffstat (limited to 'tools/timer/SysTimer_windows.cpp')
-rw-r--r-- | tools/timer/SysTimer_windows.cpp | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/tools/timer/SysTimer_windows.cpp b/tools/timer/SysTimer_windows.cpp new file mode 100644 index 0000000000..8e45b4a68e --- /dev/null +++ b/tools/timer/SysTimer_windows.cpp @@ -0,0 +1,53 @@ +/* + * Copyright 2011 Google Inc. + * + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ +#include "SysTimer_windows.h" + +#include <intrin.h> + +static ULONGLONG win_cpu_time() { + FILETIME createTime; + FILETIME exitTime; + FILETIME usrTime; + FILETIME sysTime; + if (0 == GetProcessTimes(GetCurrentProcess(), &createTime, &exitTime, &sysTime, &usrTime)) { + return 0; + } + ULARGE_INTEGER start_cpu_sys; + ULARGE_INTEGER start_cpu_usr; + start_cpu_sys.LowPart = sysTime.dwLowDateTime; + start_cpu_sys.HighPart = sysTime.dwHighDateTime; + start_cpu_usr.LowPart = usrTime.dwLowDateTime; + start_cpu_usr.HighPart = usrTime.dwHighDateTime; + return start_cpu_sys.QuadPart + start_cpu_usr.QuadPart; +} + +void SysTimer::startCpu() { + fStartCpu = win_cpu_time(); +} + +double SysTimer::endCpu() { + ULONGLONG end_cpu = win_cpu_time(); + return static_cast<double>(end_cpu - fStartCpu) / 10000.0L; +} + +// On recent Intel chips (roughly, "has Core or Atom in its name") __rdtsc will always tick +// at the CPU's maximum rate, even while power management clocks the CPU up and down. +// That's great, because it makes measuring wall time super simple. + +void SysTimer::startWall() { + fStartWall = __rdtsc(); +} + +double SysTimer::endWall() { + unsigned __int64 end = __rdtsc(); + + // This seems to, weirdly, give the CPU frequency in kHz. That's exactly what we want! + LARGE_INTEGER freq_khz; + QueryPerformanceFrequency(&freq_khz); + + return static_cast<double>(end - fStartWall) / static_cast<double>(freq_khz.QuadPart); +} |