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vii
718e67f9e1
The main thread polls nativeCallMessagesFromMainThread 146k times a second with nothing to do. Between polls it now rests 100 us: nanosleep when the governor is performance, TPAUSE (C0.2) when the CPU has WAITPKG, a spin otherwise. Sleeping under a power-saving governor lets the render thread's core clock down and drops frames, which is why TPAUSE is the default there. MOCKTAIL_ENGINE_PUMP_REST=sleep|tpause|spin overrides. The profile trace gains a slice for pumps that ran a message.
61 lines
2.1 KiB
C++
61 lines
2.1 KiB
C++
// Drives the real PaceInputPump() against an SDL window, so the pacing
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// decision is exercised end to end rather than only as pacer arithmetic.
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// Gated like the other tests that need a real SDL video driver.
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#include <SDL3/SDL.h>
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#include <gtest/gtest.h>
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#include <cstdint>
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#include <cstdlib>
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#include <string>
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#include "window/input_pump_pacer.h"
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#include "window/window.h"
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namespace mocktail {
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namespace window {
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namespace {
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bool RealSdlWindowTestsEnabled() {
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const char* enabled = std::getenv("MOCKTAIL_TEST_SDL_WINDOW");
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return enabled != nullptr && std::string(enabled) == "1";
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}
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// Unthrottled presentation must not pace the main-thread pump.
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//
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// Roblox posts its per-frame main-thread step at a time of its own choosing
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// and nothing signals the host, so the pump is a poll. A frame that misses
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// its slot slips a whole period, and the engine's slack is under a
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// millisecond, so the pacer's 240 Hz cadence is far too coarse here. The rest
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// between polls is runtime/engine_pump_rest, bounded at 100 us.
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//
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// A throttled present blocks on vsync, so the pacer still runs there.
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TEST(InputPumpPacingRuntimeTest, UnthrottledPresentationDoesNotParkThePump) {
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if (!RealSdlWindowTestsEnabled()) {
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GTEST_SKIP() << "real SDL window test was not explicitly enabled";
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}
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ASSERT_EQ(setenv("MOCKTAIL_VSYNC", "off", 1), 0);
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ASSERT_EQ(setenv("MOCKTAIL_ENABLE_TEST_GRAPHICS_STUBS", "1", 1), 0);
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ASSERT_TRUE(Init(320, 180, "input pump pacing test"));
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ASSERT_TRUE(UnthrottledPresentationRequested());
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constexpr int kTicks = 240;
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uint64_t slept_ns = 0;
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for (int tick = 0; tick < kTicks; ++tick) {
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PumpEvents();
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slept_ns += PaceInputPump();
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}
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Shutdown();
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EXPECT_EQ(slept_ns, 0U)
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<< "unthrottled ticks parked the main-thread pump for " << slept_ns
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<< " ns, which delays the engine's main-thread replies";
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}
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// The present mode policy is cached process-wide on first use, so a second
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// Init in this binary reports the mode selected above. The throttled cadence
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// is covered by the pacer's own arithmetic tests.
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} // namespace
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} // namespace window
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} // namespace mocktail
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