Vulkan: minimize-gpu-work: Skip blit from offscreen fbo

Since we only care about driver state tracking logic, blit is unrelated here. This further reduce the noise of test result. Instead of blit and swap every N frame, we will issue glFlush for offscreen rendering. The onscreen will still issue swap every frame. Bug: b/186881553 Change-Id: Id048eaafa6dcef26d851fd19f069331d240e1bf5 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2846527 Commit-Queue: Charlie Lao <cclao@google.com> Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Ian Elliott <ianelliott@google.com> Reviewed-by: Cody Northrop <cnorthrop@google.com>

Vulkan: minimize-gpu-work: Skip blit from offscreen fbo
fdb376ea · Charlie Lao · Commit Bot · 3fc83291 · fdb376ea
Commit fdb376ea authored May 03, 2021 by Charlie Lao Committed by Commit Bot May 04, 2021
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Showing with 54 additions and 44 deletions

TracePerfTest.cpp src/tests/perf_tests/TracePerfTest.cpp +54 -44

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--- a/src/tests/perf_tests/TracePerfTest.cpp
+++ b/src/tests/perf_tests/TracePerfTest.cpp
@@ -1154,56 +1154,66 @@ void TracePerfTest::drawBenchmark()
    if (params.surfaceType == SurfaceType::Offscreen)
    {
-        GLint currentDrawFBO, currentReadFBO;
+        if (gMinimizeGPUWork)
-        glGetIntegerv(GL_DRAW_FRAMEBUFFER_BINDING, &currentDrawFBO);
-        glGetIntegerv(GL_READ_FRAMEBUFFER_BINDING, &currentReadFBO);
-        glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
-        glBindFramebuffer(GL_READ_FRAMEBUFFER,
-                          mOffscreenFramebuffers[mTotalFrameCount % mMaxOffscreenBufferCount]);
-        uint32_t frameX  = (mOffscreenFrameCount % kFramesPerXY) % kFramesPerX;
-        uint32_t frameY  = (mOffscreenFrameCount % kFramesPerXY) / kFramesPerX;
-        uint32_t windowX = kOffscreenOffsetX + frameX * kOffscreenFrameWidth;
-        uint32_t windowY = kOffscreenOffsetY + frameY * kOffscreenFrameHeight;
-        if (gVerboseLogging)
-        {
-            printf("Frame %d: x %d y %d (screen x %d, screen y %d)\n", mOffscreenFrameCount, frameX,
-                   frameY, windowX, windowY);
-        }
-        GLboolean scissorTest = GL_FALSE;
-        glGetBooleanv(GL_SCISSOR_TEST, &scissorTest);
-        if (scissorTest)
-        {
-            glDisable(GL_SCISSOR_TEST);
-        }
-        glBlitFramebuffer(0, 0, mWindowWidth, mWindowHeight, windowX, windowY,
-                          windowX + kOffscreenFrameWidth, windowY + kOffscreenFrameHeight,
-                          GL_COLOR_BUFFER_BIT, GL_NEAREST);
-        if (frameX == kFramesPerX - 1 && frameY == kFramesPerY - 1)
-        {
-            swap();
-            glBindFramebuffer(GL_FRAMEBUFFER, 0);
-            glClear(GL_COLOR_BUFFER_BIT);
-            mOffscreenFrameCount = 0;
-        }
-        else
        {
+            // To keep GPU work minimum, we skip the blit.
            glFlush();
            mOffscreenFrameCount++;
        }
+        else
-        if (scissorTest)
        {
-            glEnable(GL_SCISSOR_TEST);
+            GLint currentDrawFBO, currentReadFBO;
+            glGetIntegerv(GL_DRAW_FRAMEBUFFER_BINDING, &currentDrawFBO);
+            glGetIntegerv(GL_READ_FRAMEBUFFER_BINDING, &currentReadFBO);
+            glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
+            glBindFramebuffer(
+                GL_READ_FRAMEBUFFER,
+                mOffscreenFramebuffers[mOffscreenFrameCount % mMaxOffscreenBufferCount]);
+            uint32_t frameX  = (mOffscreenFrameCount % kFramesPerXY) % kFramesPerX;
+            uint32_t frameY  = (mOffscreenFrameCount % kFramesPerXY) / kFramesPerX;
+            uint32_t windowX = kOffscreenOffsetX + frameX * kOffscreenFrameWidth;
+            uint32_t windowY = kOffscreenOffsetY + frameY * kOffscreenFrameHeight;
+            if (gVerboseLogging)
+            {
+                printf("Frame %d: x %d y %d (screen x %d, screen y %d)\n", mOffscreenFrameCount,
+                       frameX, frameY, windowX, windowY);
+            }
+            GLboolean scissorTest = GL_FALSE;
+            glGetBooleanv(GL_SCISSOR_TEST, &scissorTest);
+            if (scissorTest)
+            {
+                glDisable(GL_SCISSOR_TEST);
+            }
+            glBlitFramebuffer(0, 0, mWindowWidth, mWindowHeight, windowX, windowY,
+                              windowX + kOffscreenFrameWidth, windowY + kOffscreenFrameHeight,
+                              GL_COLOR_BUFFER_BIT, GL_NEAREST);
+            if (frameX == kFramesPerX - 1 && frameY == kFramesPerY - 1)
+            {
+                swap();
+                glBindFramebuffer(GL_FRAMEBUFFER, 0);
+                glClear(GL_COLOR_BUFFER_BIT);
+                mOffscreenFrameCount = 0;
+            }
+            else
+            {
+                glFlush();
+                mOffscreenFrameCount++;
+            }
+            if (scissorTest)
+            {
+                glEnable(GL_SCISSOR_TEST);
+            }
+            glBindFramebuffer(GL_DRAW_FRAMEBUFFER, currentDrawFBO);
+            glBindFramebuffer(GL_READ_FRAMEBUFFER, currentReadFBO);
        }
-        glBindFramebuffer(GL_DRAW_FRAMEBUFFER, currentDrawFBO);
-        glBindFramebuffer(GL_READ_FRAMEBUFFER, currentReadFBO);
        mTotalFrameCount++;
    }