Index: tools/timer/SysTimer_windows.cpp |
diff --git a/tools/timer/SysTimer_windows.cpp b/tools/timer/SysTimer_windows.cpp |
new file mode 100644 |
index 0000000000000000000000000000000000000000..8e45b4a68ed3ccabab401ec27f6138e490e56d22 |
--- /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); |
+} |