912947737a
This seems to be ~100x higher resolution than QueryPerformanceCounter. AFAIK, all our Windows perf bots have constant_tsc, so we can be a bit more direct about using rdtsc directly: it'll always tick at the max CPU frequency. Now, the question remains, what is the max CPU frequency to divide through by? It looks like QueryPerformanceFrequency actually gives the CPU frequency in kHz, suspiciously exactly what we need to divide through to get elapsed milliseconds. That was a freebie. I did some before/after comparison on slow benchmarks. Timings look the same. Going to land this without review tonight to see what happens on the bots; happy to review carefully tomorrow. R=mtklein@google.com TBR=bungeman BUG=skia: Review URL: https://codereview.chromium.org/394363003
26 lines
443 B
C++
26 lines
443 B
C++
/*
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* Copyright 2011 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SysTimer_DEFINED
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#define SysTimer_DEFINED
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//Time
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#define WIN32_LEAN_AND_MEAN 1
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#include <windows.h>
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class SysTimer {
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public:
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void startWall();
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void startCpu();
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double endCpu();
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double endWall();
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private:
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ULONGLONG fStartCpu;
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unsigned __int64 fStartWall;
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};
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#endif
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