BlackMark
30eccf749d
Run clang-format (the repo's .clang-format: LLVM base, 120 cols, tabs, Allman functions) over every source file so the tree is formatter-clean. Whitespace only -- no behavior change; full x64 + x86 suites pass. Also set SortIncludes: false in .clang-format. Windows include order is load-bearing (windows.h must precede tlhelp32.h / mmreg.h / xinput.h / dinput.h; winsock2.h must precede windows.h), and the default alphabetical sort reorders tlhelp32.h ahead of windows.h -- a build break. Leaving order alone keeps the manual, correct grouping.
44 lines
1.7 KiB
C++
44 lines
1.7 KiB
C++
// Shared helper for the per-backend present-thread overhead guards.
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//
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// The capture path (Present / SwapBuffers hook, or the Vulkan read-back) runs on the game's present
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// thread. If it stalls there, it caps the game's frame rate -- the Vulkan layer did exactly this,
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// dropping a 144 FPS game to ~3 FPS by spending ~370 ms per present reading write-combined memory.
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// Each GPU backend's in-process hook test measures the wall time its present spends with the hook
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// live vs. removed and asserts the added cost stays under one display frame, so a future regression
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// that puts a synchronous read-back / stall back on the present thread fails the test.
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#pragma once
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#include <windows.h>
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namespace cooptest {
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inline double now_ms()
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{
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LARGE_INTEGER f, c;
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QueryPerformanceFrequency(&f);
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QueryPerformanceCounter(&c);
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return 1000.0 * static_cast<double>(c.QuadPart) / static_cast<double>(f.QuadPart);
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}
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// Average wall time of `present()` over n frames, calling `render()` (untimed) before each so a
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// fresh frame is produced. Returns milliseconds per present.
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template <class RenderFn, class PresentFn>
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double avg_present_ms(int n, RenderFn render, PresentFn present)
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{
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render();
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present(); // warm (first present/resource setup)
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double total = 0;
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for (int i = 0; i < n; ++i) {
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render();
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const double a = now_ms();
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present();
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total += now_ms() - a;
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}
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return n > 0 ? total / n : 0.0;
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}
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// One 60 Hz display frame. The capture's added present-thread cost must stay well under this or it
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// throttles the game; the Vulkan bug added ~370 ms (22x over budget). Generous on purpose -- the
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// guard targets the catastrophic-stall class, not micro-overhead, so it never flakes on jitter.
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inline constexpr double kPresentOverheadBudgetMs = 16.7;
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} // namespace cooptest
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