gpu/perftests/texture_upload_perftest.cc

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include <algorithm>
   6 #include <vector>
   7
   8 #include "base/containers/small_map.h"
   9 #include "base/logging.h"
  10 #include "base/memory/ref_counted.h"
  11 #include "base/memory/scoped_ptr.h"
  12 #include "base/strings/stringprintf.h"
  13 #include "gpu/perftests/measurements.h"
  14 #include "testing/gmock/include/gmock/gmock.h"
  15 #include "testing/gtest/include/gtest/gtest.h"
  16 #include "testing/perf/perf_test.h"
  17 #include "ui/gfx/geometry/size.h"
  18 #include "ui/gfx/geometry/vector2d_f.h"
  19 #include "ui/gl/gl_bindings.h"
  20 #include "ui/gl/gl_context.h"
  21 #include "ui/gl/gl_enums.h"
  22 #include "ui/gl/gl_surface.h"
  23 #include "ui/gl/gl_version_info.h"
  24 #include "ui/gl/gpu_timing.h"
  25 #include "ui/gl/scoped_make_current.h"
  26
  27 #if defined(USE_OZONE)
  28 #include "base/message_loop/message_loop.h"
  29 #endif
  30
  31 namespace gpu {
  32 namespace {
  33
  34 const int kUploadPerfWarmupRuns = 5;
  35 const int kUploadPerfTestRuns = 30;
  36
  37 #define SHADER(Src) #Src
  38
  39 // clang-format off
  40 const char kVertexShader[] =
  41 SHADER(
  42   uniform vec2 translation;
  43   attribute vec2 a_position;
  44   attribute vec2 a_texCoord;
  45   varying vec2 v_texCoord;
  46   void main() {
  47     gl_Position = vec4(
  48         translation.x + a_position.x, translation.y + a_position.y, 0.0, 1.0);
  49     v_texCoord = a_texCoord;
  50   }
  51 );
  52 const char kShaderDefaultFloatPrecision[] =
  53 SHADER(
  54   precision mediump float;
  55 );
  56 const char kFragmentShader[] =
  57 SHADER(
  58   uniform sampler2D a_texture;
  59   varying vec2 v_texCoord;
  60   void main() {
  61     gl_FragColor = texture2D(a_texture, v_texCoord);
  62   }
  63 );
  64 // clang-format on
  65
  66 void CheckNoGlError(const std::string& msg) {
  67   CHECK_EQ(static_cast<GLenum>(GL_NO_ERROR), glGetError()) << " " << msg;
  68 }
  69
  70 // Utility function to compile a shader from a string.
  71 GLuint LoadShader(const GLenum type, const char* const src) {
  72   GLuint shader = 0;
  73   shader = glCreateShader(type);
  74   CHECK_NE(0u, shader);
  75   glShaderSource(shader, 1, &src, NULL);
  76   glCompileShader(shader);
  77
  78   GLint compiled = 0;
  79   glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
  80   if (compiled == 0) {
  81     GLint len = 0;
  82     glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &len);
  83     if (len > 1) {
  84       scoped_ptr<char[]> error_log(new char[len]);
  85       glGetShaderInfoLog(shader, len, NULL, error_log.get());
  86       LOG(ERROR) << "Error compiling shader: " << error_log.get();
  87     }
  88   }
  89   CHECK_NE(0, compiled);
  90   return shader;
  91 }
  92
  93 int GLFormatBytePerPixel(GLenum format) {
  94   DCHECK(format == GL_RGBA || format == GL_LUMINANCE || format == GL_RED_EXT);
  95   return format == GL_RGBA ? 4 : 1;
  96 }
  97
  98 GLenum GLFormatToInternalFormat(GLenum format) {
  99   return format == GL_RED ? GL_R8 : format;
 100 }
 101
 102 GLenum GLFormatToStorageFormat(GLenum format) {
 103   switch (format) {
 104     case GL_RGBA:
 105       return GL_RGBA8;
 106     case GL_LUMINANCE:
 107       return GL_LUMINANCE8;
 108     case GL_RED:
 109       return GL_R8;
 110     default:
 111       NOTREACHED();
 112   }
 113   return 0;
 114 }
 115
 116 void GenerateTextureData(const gfx::Size& size,
 117                          int bytes_per_pixel,
 118                          const int seed,
 119                          std::vector<uint8>* const pixels) {
 120   // Row bytes has to be multiple of 4 (GL_PACK_ALIGNMENT defaults to 4).
 121   int stride = ((size.width() * bytes_per_pixel) + 3) & ~0x3;
 122   pixels->resize(size.height() * stride);
 123   for (int y = 0; y < size.height(); ++y) {
 124     for (int x = 0; x < size.width(); ++x) {
 125       for (int channel = 0; channel < bytes_per_pixel; ++channel) {
 126         int index = y * stride + x * bytes_per_pixel;
 127         pixels->at(index) = (index + (seed << 2)) % (0x20 << channel);
 128       }
 129     }
 130   }
 131 }
 132
 133 // Compare a buffer containing pixels in a specified format to GL_RGBA buffer
 134 // where the former buffer have been uploaded as a texture and drawn on the
 135 // RGBA buffer.
 136 bool CompareBufferToRGBABuffer(GLenum format,
 137                                const gfx::Size& size,
 138                                const std::vector<uint8>& pixels,
 139                                const std::vector<uint8>& rgba) {
 140   int bytes_per_pixel = GLFormatBytePerPixel(format);
 141   int pixels_stride = ((size.width() * bytes_per_pixel) + 3) & ~0x3;
 142   int rgba_stride = size.width() * GLFormatBytePerPixel(GL_RGBA);
 143   for (int y = 0; y < size.height(); ++y) {
 144     for (int x = 0; x < size.width(); ++x) {
 145       int rgba_index = y * rgba_stride + x * GLFormatBytePerPixel(GL_RGBA);
 146       int pixels_index = y * pixels_stride + x * bytes_per_pixel;
 147       uint8 expected[4] = {0};
 148       switch (format) {
 149         case GL_LUMINANCE:  // (L_t, L_t, L_t, 1)
 150           expected[1] = pixels[pixels_index];
 151           expected[2] = pixels[pixels_index];
 152         case GL_RED:  // (R_t, 0, 0, 1)
 153           expected[0] = pixels[pixels_index];
 154           expected[3] = 255;
 155           break;
 156         case GL_RGBA:  // (R_t, G_t, B_t, A_t)
 157           memcpy(expected, &pixels[pixels_index], 4);
 158           break;
 159         default:
 160           NOTREACHED();
 161       }
 162       if (memcmp(&rgba[rgba_index], expected, 4)) {
 163         return false;
 164       }
 165     }
 166   }
 167   return true;
 168 }
 169
 170 // PerfTest to check costs of texture upload at different stages
 171 // on different platforms.
 172 class TextureUploadPerfTest : public testing::Test {
 173  public:
 174   TextureUploadPerfTest() : fbo_size_(1024, 1024) {}
 175
 176   // Overridden from testing::Test
 177   void SetUp() override {
 178 #if defined(USE_OZONE)
 179     // On Ozone, the backend initializes the event system using a UI
 180     // thread.
 181     base::MessageLoopForUI main_loop;
 182 #endif
 183     static bool gl_initialized = gfx::GLSurface::InitializeOneOff();
 184     DCHECK(gl_initialized);
 185     // Initialize an offscreen surface and a gl context.
 186     surface_ = gfx::GLSurface::CreateOffscreenGLSurface(gfx::Size());
 187     gl_context_ = gfx::GLContext::CreateGLContext(NULL,  // share_group
 188                                                   surface_.get(),
 189                                                   gfx::PreferIntegratedGpu);
 190     ui::ScopedMakeCurrent smc(gl_context_.get(), surface_.get());
 191     glGenTextures(1, &color_texture_);
 192     glBindTexture(GL_TEXTURE_2D, color_texture_);
 193     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 194     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 195     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 196     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 197     glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, fbo_size_.width(),
 198                  fbo_size_.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
 199
 200     glGenFramebuffersEXT(1, &framebuffer_object_);
 201     glBindFramebufferEXT(GL_FRAMEBUFFER, framebuffer_object_);
 202
 203     glFramebufferTexture2DEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
 204                               GL_TEXTURE_2D, color_texture_, 0);
 205     DCHECK_EQ(static_cast<GLenum>(GL_FRAMEBUFFER_COMPLETE),
 206               glCheckFramebufferStatusEXT(GL_FRAMEBUFFER));
 207
 208     glViewport(0, 0, fbo_size_.width(), fbo_size_.height());
 209     gpu_timing_client_ = gl_context_->CreateGPUTimingClient();
 210
 211     if (gpu_timing_client_->IsAvailable()) {
 212       LOG(INFO) << "Gpu timing initialized with timer type: "
 213                 << gpu_timing_client_->GetTimerTypeName();
 214     } else {
 215       LOG(WARNING) << "Can't initialize gpu timing";
 216     }
 217     // Prepare a simple program and a vertex buffer that will be
 218     // used to draw a quad on the offscreen surface.
 219     vertex_shader_ = LoadShader(GL_VERTEX_SHADER, kVertexShader);
 220
 221     bool is_gles = gfx::GetGLImplementation() == gfx::kGLImplementationEGLGLES2;
 222     fragment_shader_ = LoadShader(
 223         GL_FRAGMENT_SHADER,
 224         base::StringPrintf("%s%s", is_gles ? kShaderDefaultFloatPrecision : "",
 225                            kFragmentShader).c_str());
 226     program_object_ = glCreateProgram();
 227     CHECK_NE(0u, program_object_);
 228
 229     glAttachShader(program_object_, vertex_shader_);
 230     glAttachShader(program_object_, fragment_shader_);
 231     glBindAttribLocation(program_object_, 0, "a_position");
 232     glBindAttribLocation(program_object_, 1, "a_texCoord");
 233     glLinkProgram(program_object_);
 234
 235     GLint linked = -1;
 236     glGetProgramiv(program_object_, GL_LINK_STATUS, &linked);
 237     CHECK_NE(0, linked);
 238     glUseProgram(program_object_);
 239     glUniform1i(sampler_location_, 0);
 240     translation_location_ =
 241         glGetUniformLocation(program_object_, "translation");
 242     DCHECK_NE(-1, translation_location_);
 243     glUniform2f(translation_location_, 0.0f, 0.0f);
 244
 245     sampler_location_ = glGetUniformLocation(program_object_, "a_texture");
 246     CHECK_NE(-1, sampler_location_);
 247
 248     glGenBuffersARB(1, &vertex_buffer_);
 249     CHECK_NE(0u, vertex_buffer_);
 250     DCHECK_NE(0u, vertex_buffer_);
 251     glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_);
 252     glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(GLfloat) * 4, 0);
 253     glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(GLfloat) * 4,
 254                           reinterpret_cast<void*>(sizeof(GLfloat) * 2));
 255     glEnableVertexAttribArray(0);
 256     glEnableVertexAttribArray(1);
 257     CheckNoGlError("glEnableVertexAttribArray");
 258
 259     has_texture_storage_ =
 260         gl_context_->GetVersionInfo()->is_es3 ||
 261         gl_context_->HasExtension("GL_EXT_texture_storage") ||
 262         gl_context_->HasExtension("GL_ARB_texture_storage");
 263   }
 264
 265   void GenerateVertexBuffer(const gfx::Size& size) {
 266     DCHECK_NE(0u, vertex_buffer_);
 267     glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_);
 268     // right and top are in clipspace
 269     float right = -1.f + 2.f * size.width() / fbo_size_.width();
 270     float top = -1.f + 2.f * size.height() / fbo_size_.height();
 271     // Four vertexes, one per line. Each vertex has two components per
 272     // position and two per texcoord.
 273     // It represents a quad formed by two triangles if interpreted
 274     // as a tristrip.
 275
 276     // clang-format off
 277     GLfloat data[16] = {
 278       -1.f, -1.f,    0.f, 0.f,
 279       right, -1.f,   1.f, 0.f,
 280       -1.f, top,     0.f, 1.f,
 281       right, top,    1.f, 1.f};
 282     // clang-format on
 283     glBufferData(GL_ARRAY_BUFFER, sizeof(data), data, GL_STATIC_DRAW);
 284     CheckNoGlError("glBufferData");
 285   }
 286
 287   void TearDown() override {
 288     ui::ScopedMakeCurrent smc(gl_context_.get(), surface_.get());
 289     glDeleteProgram(program_object_);
 290     glDeleteShader(vertex_shader_);
 291     glDeleteShader(fragment_shader_);
 292     glDeleteBuffersARB(1, &vertex_buffer_);
 293
 294     glBindFramebufferEXT(GL_FRAMEBUFFER, 0);
 295     glDeleteFramebuffersEXT(1, &framebuffer_object_);
 296     glDeleteTextures(1, &color_texture_);
 297     CheckNoGlError("glDeleteTextures");
 298
 299     gpu_timing_client_ = nullptr;
 300     gl_context_ = nullptr;
 301     surface_ = nullptr;
 302   }
 303
 304  protected:
 305   GLuint CreateGLTexture(const GLenum format,
 306                          const gfx::Size& size,
 307                          const bool specify_storage) {
 308     GLuint texture_id = 0;
 309     glActiveTexture(GL_TEXTURE0);
 310     glGenTextures(1, &texture_id);
 311     glBindTexture(GL_TEXTURE_2D, texture_id);
 312     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 313     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 314     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 315     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 316     if (specify_storage) {
 317       if (has_texture_storage_) {
 318         glTexStorage2DEXT(GL_TEXTURE_2D, 1, GLFormatToStorageFormat(format),
 319                           size.width(), size.height());
 320         CheckNoGlError("glTexStorage2DEXT");
 321       } else {
 322         glTexImage2D(GL_TEXTURE_2D, 0, GLFormatToInternalFormat(format),
 323                      size.width(), size.height(), 0, format, GL_UNSIGNED_BYTE,
 324                      nullptr);
 325         CheckNoGlError("glTexImage2D");
 326       }
 327     }
 328     return texture_id;
 329   }
 330
 331   void UploadTexture(GLuint texture_id,
 332                      const gfx::Size& size,
 333                      const std::vector<uint8>& pixels,
 334                      GLenum format,
 335                      const bool subimage) {
 336     if (subimage) {
 337       glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, size.width(), size.height(),
 338                       format, GL_UNSIGNED_BYTE, &pixels[0]);
 339       CheckNoGlError("glTexSubImage2D");
 340     } else {
 341       glTexImage2D(GL_TEXTURE_2D, 0, GLFormatToInternalFormat(format),
 342                    size.width(), size.height(), 0, format, GL_UNSIGNED_BYTE,
 343                    &pixels[0]);
 344       CheckNoGlError("glTexImage2D");
 345     }
 346   }
 347
 348   // Upload and draw on the offscren surface.
 349   // Return a list of pair. Each pair describe a gl operation and the wall
 350   // time elapsed in milliseconds.
 351   std::vector<Measurement> UploadAndDraw(GLuint texture_id,
 352                                          const gfx::Size& size,
 353                                          const std::vector<uint8>& pixels,
 354                                          const GLenum format,
 355                                          const bool subimage) {
 356     MeasurementTimers tex_timers(gpu_timing_client_.get());
 357     UploadTexture(texture_id, size, pixels, format, subimage);
 358     tex_timers.Record();
 359
 360     MeasurementTimers first_draw_timers(gpu_timing_client_.get());
 361     glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
 362     first_draw_timers.Record();
 363
 364     MeasurementTimers draw_timers(gpu_timing_client_.get());
 365     glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
 366     draw_timers.Record();
 367
 368     MeasurementTimers finish_timers(gpu_timing_client_.get());
 369     glFinish();
 370     CheckNoGlError("glFinish");
 371     finish_timers.Record();
 372
 373     std::vector<uint8> pixels_rendered(size.GetArea() * 4);
 374     glReadPixels(0, 0, size.width(), size.height(), GL_RGBA, GL_UNSIGNED_BYTE,
 375                  &pixels_rendered[0]);
 376     CheckNoGlError("glReadPixels");
 377     EXPECT_TRUE(
 378         CompareBufferToRGBABuffer(format, size, pixels, pixels_rendered))
 379         << "Format is: " << gfx::GLEnums::GetStringEnum(format);
 380
 381     std::vector<Measurement> measurements;
 382     bool gpu_timer_errors =
 383         gpu_timing_client_->IsAvailable() &&
 384         gpu_timing_client_->CheckAndResetTimerErrors();
 385     if (!gpu_timer_errors) {
 386       measurements.push_back(tex_timers.GetAsMeasurement(
 387           subimage ? "texsubimage2d" : "teximage2d"));
 388       measurements.push_back(
 389           first_draw_timers.GetAsMeasurement("firstdrawarrays"));
 390       measurements.push_back(draw_timers.GetAsMeasurement("drawarrays"));
 391       measurements.push_back(finish_timers.GetAsMeasurement("finish"));
 392     }
 393     return measurements;
 394   }
 395
 396   void RunUploadAndDrawMultipleTimes(const gfx::Size& size,
 397                                      const GLenum format,
 398                                      const bool subimage) {
 399     std::vector<uint8> pixels;
 400     base::SmallMap<std::map<std::string, Measurement>>
 401         aggregates;  // indexed by name
 402     int successful_runs = 0;
 403     GLuint texture_id = CreateGLTexture(format, size, subimage);
 404     for (int i = 0; i < kUploadPerfWarmupRuns + kUploadPerfTestRuns; ++i) {
 405       GenerateTextureData(size, GLFormatBytePerPixel(format), i + 1, &pixels);
 406       auto run = UploadAndDraw(texture_id, size, pixels, format, subimage);
 407       if (i < kUploadPerfWarmupRuns || !run.size()) {
 408         continue;
 409       }
 410       successful_runs++;
 411       for (const Measurement& measurement : run) {
 412         auto& aggregate = aggregates[measurement.name];
 413         aggregate.name = measurement.name;
 414         aggregate.Increment(measurement);
 415       }
 416     }
 417     glDeleteTextures(1, &texture_id);
 418
 419     std::string graph_name = base::StringPrintf(
 420         "%d_%s", size.width(), gfx::GLEnums::GetStringEnum(format).c_str());
 421     if (subimage) {
 422       graph_name += "_sub";
 423     }
 424
 425     if (successful_runs) {
 426       for (const auto& entry : aggregates) {
 427         const auto m = entry.second.Divide(successful_runs);
 428         m.PrintResult(graph_name);
 429       }
 430     }
 431     perf_test::PrintResult("sample_runs", "", graph_name,
 432                            static_cast<size_t>(successful_runs), "laps", true);
 433   }
 434
 435   const gfx::Size fbo_size_;  // for the fbo
 436   scoped_refptr<gfx::GLContext> gl_context_;
 437   scoped_refptr<gfx::GLSurface> surface_;
 438   scoped_refptr<gfx::GPUTimingClient> gpu_timing_client_;
 439
 440   GLuint color_texture_ = 0;
 441   GLuint framebuffer_object_ = 0;
 442   GLuint vertex_shader_ = 0;
 443   GLuint fragment_shader_ = 0;
 444   GLuint program_object_ = 0;
 445   GLint sampler_location_ = -1;
 446   GLint translation_location_ = -1;
 447   GLuint vertex_buffer_ = 0;
 448
 449   bool has_texture_storage_ = false;
 450 };
 451
 452 // Perf test that generates, uploads and draws a texture on a surface repeatedly
 453 // and prints out aggregated measurements for all the runs.
 454 TEST_F(TextureUploadPerfTest, upload) {
 455   int sizes[] = {21, 128, 256, 512, 1024};
 456   std::vector<GLenum> formats;
 457   formats.push_back(GL_RGBA);
 458
 459   if (!gl_context_->GetVersionInfo()->is_es3) {
 460     // Used by default for ResourceProvider::yuv_resource_format_.
 461     formats.push_back(GL_LUMINANCE);
 462   }
 463
 464   ui::ScopedMakeCurrent smc(gl_context_.get(), surface_.get());
 465   const bool has_texture_rg = gl_context_->GetVersionInfo()->is_es3 ||
 466                               gl_context_->HasExtension("GL_EXT_texture_rg") ||
 467                               gl_context_->HasExtension("GL_ARB_texture_rg");
 468
 469   if (has_texture_rg) {
 470     // Used as ResourceProvider::yuv_resource_format_ if
 471     // {ARB,EXT}_texture_rg are available.
 472     formats.push_back(GL_RED);
 473   }
 474
 475   for (int side : sizes) {
 476     ASSERT_GE(fbo_size_.width(), side);
 477     ASSERT_GE(fbo_size_.height(), side);
 478     gfx::Size size(side, side);
 479     GenerateVertexBuffer(size);
 480     for (GLenum format : formats) {
 481       RunUploadAndDrawMultipleTimes(size, format, true);  // use glTexSubImage2D
 482       RunUploadAndDrawMultipleTimes(size, format, false);  // use glTexImage2D
 483     }
 484   }
 485 }
 486
 487 // Perf test to check if the driver is doing texture renaming.
 488 // This test creates one GL texture_id and four different images. For
 489 // every image it uploads it using texture_id and it draws multiple
 490 // times. The cpu/wall time and the gpu time for all the uploads and
 491 // draws, but before glFinish, is computed and is printed out at the end as
 492 // "upload_and_draw". If the gpu time is >> than the cpu/wall time we expect the
 493 // driver to do texture renaming: this means that while the gpu is drawing using
 494 // texture_id it didn't block cpu side the texture upload using the same
 495 // texture_id.
 496 TEST_F(TextureUploadPerfTest, renaming) {
 497   gfx::Size texture_size(fbo_size_.width() / 2, fbo_size_.height() / 2);
 498
 499   std::vector<uint8> pixels[4];
 500   for (int i = 0; i < 4; ++i) {
 501     GenerateTextureData(texture_size, 4, i + 1, &pixels[i]);
 502   }
 503
 504   ui::ScopedMakeCurrent smc(gl_context_.get(), surface_.get());
 505   GenerateVertexBuffer(texture_size);
 506
 507   gfx::Vector2dF positions[] = {gfx::Vector2dF(0.f, 0.f),
 508                                 gfx::Vector2dF(1.f, 0.f),
 509                                 gfx::Vector2dF(0.f, 1.f),
 510                                 gfx::Vector2dF(1.f, 1.f)};
 511   GLuint texture_id = CreateGLTexture(GL_RGBA, texture_size, true);
 512
 513   MeasurementTimers upload_and_draw_timers(gpu_timing_client_.get());
 514
 515   for (int i = 0; i < 4; ++i) {
 516     UploadTexture(texture_id, texture_size, pixels[i % 4], GL_RGBA, true);
 517     DCHECK_NE(-1, translation_location_);
 518     glUniform2f(translation_location_, positions[i % 4].x(),
 519                 positions[i % 4].y());
 520     // Draw the same quad multiple times to make sure that the time spent on the
 521     // gpu is more than the cpu time.
 522     for (int draw = 0; draw < 128; ++draw) {
 523       glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
 524     }
 525   }
 526
 527   upload_and_draw_timers.Record();
 528   MeasurementTimers finish_timers(gpu_timing_client_.get());
 529   glFinish();
 530   CheckNoGlError("glFinish");
 531   finish_timers.Record();
 532
 533   glDeleteTextures(1, &texture_id);
 534
 535   for (int i = 0; i < 4; ++i) {
 536     std::vector<uint8> pixels_rendered(texture_size.GetArea() * 4);
 537     glReadPixels(texture_size.width() * positions[i].x(),
 538                  texture_size.height() * positions[i].y(), texture_size.width(),
 539                  texture_size.height(), GL_RGBA, GL_UNSIGNED_BYTE,
 540                  &pixels_rendered[0]);
 541     CheckNoGlError("glReadPixels");
 542     ASSERT_EQ(pixels[i].size(), pixels_rendered.size());
 543     EXPECT_EQ(pixels[i], pixels_rendered);
 544   }
 545
 546   bool gpu_timer_errors = gpu_timing_client_->IsAvailable() &&
 547                           gpu_timing_client_->CheckAndResetTimerErrors();
 548   if (!gpu_timer_errors) {
 549     upload_and_draw_timers.GetAsMeasurement("upload_and_draw")
 550         .PrintResult("renaming");
 551     finish_timers.GetAsMeasurement("finish").PrintResult("renaming");
 552   }
 553 }
 554
 555 }  // namespace
 556 }  // namespace gpu