void StepWorldV3OpenCL(world_t &world, float dt, unsigned n)
{
// OpenCL setup
// platform
std::vector<cl::Platform> platforms;
cl::Platform::get(&platforms);
if (platforms.size() == 0)
throw std::runtime_error("No OpenCL platforms found.");
std::cerr << "Found " << platforms.size() << " platforms\n";
for (unsigned i = 0; i < platforms.size(); i++) {
std::string vendor = platforms[i].getInfo<CL_PLATFORM_VENDOR>();
std::cerr << " Platform " << i << " : " << vendor << "\n";
}
int selectedPlatform = 0;
if (getenv("HPCE_SELECT_PLATFORM")) {
selectedPlatform = atoi(getenv("HPCE_SELECT_PLATFORM"));
}
std::cerr << "Choosing platform " << selectedPlatform << "\n";
cl::Platform platform = platforms.at(selectedPlatform);
// device
std::vector<cl::Device> devices;
platform.getDevices(CL_DEVICE_TYPE_ALL, &devices);
if (devices.size() == 0) {
throw std::runtime_error("No opencl devices found.\n");
}
std::cerr << "Found " << devices.size() << " devices\n";
for (unsigned i = 0; i < devices.size(); i++) {
std::string name = devices[i].getInfo<CL_DEVICE_NAME>();
std::cerr << " Device " << i << " : " << name << "\n";
}
int selectedDevice = 0;
if (getenv("HPCE_SELECT_DEVICE")) {
selectedDevice = atoi(getenv("HPCE_SELECT_DEVICE"));
}
std::cerr << "Choosing device " << selectedDevice << "\n";
cl::Device device = devices.at(selectedDevice);
// context
cl::Context context(devices);
std::string kernelSource = LoadSource("step_world_v3_kernel.cl");
cl::Program::Sources sources; // A vector of (data,length) pairs
sources.push_back(
std::make_pair(kernelSource.c_str(),
kernelSource.size() + 1)); // push on our single string
cl::Program program(context, sources);
try { program.build(devices); }
catch (...)
{
for (unsigned i = 0; i < devices.size(); i++) {
std::cerr << "Log for device " << devices[i].getInfo<CL_DEVICE_NAME>()
<< ":\n\n";
std::cerr << program.getBuildInfo<CL_PROGRAM_BUILD_LOG>(devices[i])
<< "\n\n";
}
throw;
}
size_t cbBuffer = 4 * world.w * world.h;
cl::Buffer buffProperties(context, CL_MEM_READ_ONLY, cbBuffer);
cl::Buffer buffState(context, CL_MEM_READ_ONLY, cbBuffer);
cl::Buffer buffBuffer(context, CL_MEM_WRITE_ONLY, cbBuffer);
cl::Kernel kernel(program, "kernel_xy");
float outer = world.alpha * dt; // We spread alpha to other cells per time
float inner = 1 - outer / 4; // Anything that doesn't spread stays
kernel.setArg(0, inner);
kernel.setArg(1, outer);
kernel.setArg(2, buffState);
kernel.setArg(3, buffProperties);
kernel.setArg(4, buffBuffer);
cl::CommandQueue queue(context, device);
queue.enqueueWriteBuffer(buffProperties, CL_TRUE, 0, cbBuffer,
&world.properties[0]);
unsigned w = world.w, h = world.h;
// This is our temporary working space
std::vector<float> buffer(w * h);
cl::NDRange offset(0, 0); // Always start iterations at x=0, y=0
cl::NDRange globalSize(w, h); // Global size must match the original loops
cl::NDRange localSize = cl::NullRange; // We don't care about local size
for (unsigned t = 0; t < n; t++) {
cl::Event evCopiedState;
queue.enqueueWriteBuffer(buffState, CL_FALSE, 0, cbBuffer, &world.state[0],
NULL, &evCopiedState);
std::vector<cl::Event> kernelDependencies(1, evCopiedState);
cl::Event evExecutedKernel;
queue.enqueueNDRangeKernel(kernel, offset, globalSize, localSize,
&kernelDependencies, &evExecutedKernel);
std::vector<cl::Event> copyBackDependencies(1, evExecutedKernel);
queue.enqueueReadBuffer(buffBuffer, CL_TRUE, 0, cbBuffer, &buffer[0],
©BackDependencies);
std::swap(world.state, buffer);
world.t += dt; // We have moved the world forwards in time
}
}
void StepWorldV4DoubleBuffered(world_t &world, float dt, unsigned n)
{
// Get platforms
std::vector<cl::Platform> platforms;
cl::Platform::get(&platforms);
if (platforms.size() == 0)
throw std::runtime_error("No OpenCL platforms found.");
#ifdef DEBUG
std::cerr << "Found " << platforms.size() << " platforms\n";
for (unsigned i = 0; i < platforms.size(); i++)
{
std::string vendor = platforms[0].getInfo<CL_PLATFORM_VENDOR>();
std::cerr << " Platform " << i << " : " << vendor << "\n";
}
#endif
// select platforms
int selectedPlatform = 0;
if (getenv("HPCE_SELECT_PLATFORM"))
{
selectedPlatform = atoi(getenv("HPCE_SELECT_PLATFORM"));
}
#ifdef DEBUG
std::cerr << "Choosing platform " << selectedPlatform << "\n";
#endif
cl::Platform platform = platforms.at(selectedPlatform);
// Get devices
std::vector<cl::Device> devices;
platform.getDevices(CL_DEVICE_TYPE_ALL, &devices);
if (devices.size() == 0)
{
throw std::runtime_error("No opencl devices found.\n");
}
#ifdef DEBUG
std::cerr << "Found " << devices.size() << " devices\n";
for (unsigned i = 0; i < devices.size(); i++)
{
std::string name = devices[i].getInfo<CL_DEVICE_NAME>();
std::cerr << " Device " << i << " : " << name << "\n";
}
#endif
// Select device
int selectedDevice = 0;
if (getenv("HPCE_SELECT_DEVICE"))
{
selectedDevice = atoi(getenv("HPCE_SELECT_DEVICE"));
}
#ifdef DEBUG
std::cerr << "Choosing device " << selectedDevice << "\n";
#endif
cl::Device device = devices.at(selectedDevice);
// Create context
cl::Context context(devices);
// Load kernel to string
std::string kernelSource = LoadSource("step_world_v3_kernel.cl");
// Load kernel to sources
cl::Program::Sources sources; // A vector of (data,length) pairs
sources.push_back(std::make_pair(kernelSource.c_str(), kernelSource.size() + 1)); // push on our single string
// Create program from context
cl::Program program(context, sources);
#ifdef DEBUG
try
{
program.build(devices);
}
catch (...)
{
for (unsigned i = 0; i < devices.size(); i++)
{
std::cerr << "Log for device " << devices[i].getInfo<CL_DEVICE_NAME>() << ":\n\n";
std::cerr << program.getBuildInfo<CL_PROGRAM_BUILD_LOG>(devices[i]) << "\n\n";
}
throw;
}
#else
program.build(devices);
#endif
size_t cbBuffer = 4 * world.w * world.h;
cl::Buffer buffProperties(context, CL_MEM_READ_ONLY, cbBuffer);
cl::Buffer buffState(context, CL_MEM_READ_WRITE, cbBuffer);
cl::Buffer buffBuffer(context, CL_MEM_READ_WRITE, cbBuffer);
cl::Kernel kernel(program, "kernel_xy");
unsigned w = world.w, h = world.h;
float outer = world.alpha * dt; // We spread alpha to other cells per time
float inner = 1 - outer / 4; // Anything that doesn't spread stays
kernel.setArg(0, inner);
kernel.setArg(1, outer);
kernel.setArg(3, buffProperties);
cl::CommandQueue queue(context, device);
queue.enqueueWriteBuffer(buffProperties, CL_TRUE, 0, cbBuffer, &world.properties[0]);
queue.enqueueWriteBuffer(buffState, CL_TRUE, 0, cbBuffer, &world.state[0]);
cl::NDRange offset(0, 0); // Always start iterations at x=0, y=0
cl::NDRange globalSize(w, h); // Global size must match the original loops
cl::NDRange localSize = cl::NullRange; // We don't care about local size
for (unsigned t = 0; t < n; t++)
{
kernel.setArg(2, buffState);
kernel.setArg(4, buffBuffer);
queue.enqueueNDRangeKernel(kernel, offset, globalSize, localSize);
queue.enqueueBarrier();
// queue.enqueueCopyBuffer(buffBuffer, buffState, 0, 0, cbBuffer, 0, NULL);
// queue.enqueueBarrier();
std::swap(buffState, buffBuffer);
// queue.enqueueReadBuffer(buffBuffer, CL_TRUE, 0, cbBuffer, &buffer[0]);
// Swapping rather than assigning is cheaper: just a pointer swap
// rather than a memcpy, so O(1) rather than O(w*h)
world.t += dt; // We have moved the world forwards in time
} // end of for(t...
// This is our temporary working space
queue.enqueueReadBuffer(buffState, CL_TRUE, 0, cbBuffer, &world.state[0]);
}