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35 #ifndef GMX_GPU_UTILS_DEVICEBUFFER_SYCL_H
36 #define GMX_GPU_UTILS_DEVICEBUFFER_SYCL_H
38 /*! \libinternal \file
39 * \brief Implements the DeviceBuffer type and routines for SYCL.
40 * Should only be included directly by the main DeviceBuffer file devicebuffer.h.
41 * TODO: the intent is for DeviceBuffer to become a class.
43 * \author Artem Zhmurov <zhmurov@gmail.com>
44 * \author Erik Lindahl <erik.lindahl@gmail.com>
45 * \author Andrey Alekseenko <al42and@gmail.com>
52 #include "gromacs/gpu_utils/device_context.h"
53 #include "gromacs/gpu_utils/device_stream.h"
54 #include "gromacs/gpu_utils/devicebuffer_datatype.h"
55 #include "gromacs/gpu_utils/gmxsycl.h"
56 #include "gromacs/gpu_utils/gpu_utils.h" //only for GpuApiCallBehavior
57 #include "gromacs/gpu_utils/gputraits_sycl.h"
58 #include "gromacs/utility/fatalerror.h"
59 #include "gromacs/utility/gmxassert.h"
60 #include "gromacs/utility/stringutil.h"
64 class DeviceBuffer<T>::ClSyclBufferWrapper : public cl::sycl::buffer<T, 1>
66 using cl::sycl::buffer<T, 1>::buffer; // Get all the constructors
70 using ClSyclBufferWrapper = typename DeviceBuffer<T>::ClSyclBufferWrapper;
74 DeviceBuffer<T>::DeviceBuffer() : buffer_(nullptr)
80 DeviceBuffer<T>::~DeviceBuffer() = default;
82 //! Copy constructor (references the same underlying SYCL buffer).
84 DeviceBuffer<T>::DeviceBuffer(DeviceBuffer<T> const& src)
88 buffer_ = std::make_unique<ClSyclBufferWrapper>(*src.buffer_);
98 DeviceBuffer<T>::DeviceBuffer(DeviceBuffer<T>&& src) noexcept = default;
100 //! Copy assignment (references the same underlying SYCL buffer).
102 DeviceBuffer<T>& DeviceBuffer<T>::operator=(DeviceBuffer<T> const& src)
106 buffer_ = std::make_unique<ClSyclBufferWrapper>(*src.buffer_);
110 buffer_.reset(nullptr);
117 DeviceBuffer<T>& DeviceBuffer<T>::operator=(DeviceBuffer<T>&& src) noexcept = default;
119 /*! \brief Dummy assignment operator to allow compilation of some cross-platform code.
121 * A hacky way to make SYCL implementation of DeviceBuffer compatible with details of CUDA and
122 * OpenCL implementations.
124 * \todo Should be removed after DeviceBuffer refactoring.
126 * \tparam T Type of buffer content.
127 * \param nullPtr \c std::nullptr. Not possible to assign any other pointers.
130 DeviceBuffer<T>& DeviceBuffer<T>::operator=(std::nullptr_t nullPtr)
132 buffer_.reset(nullPtr);
137 namespace gmx::internal
139 //! Shorthand alias to create a placeholder SYCL accessor with chosen data type and access mode.
140 template<class T, cl::sycl::access::mode mode>
141 using PlaceholderAccessor =
142 cl::sycl::accessor<T, 1, mode, cl::sycl::access::target::global_buffer, cl::sycl::access::placeholder::true_t>;
143 } // namespace gmx::internal
146 * Thin wrapper around placeholder accessor that allows implicit construction from \c DeviceBuffer.
148 * "Placeholder accessor" is an indicator of the intent to create an accessor for certain buffer
149 * of a certain type, that is not yet bound to a specific command group handler (device). Such
150 * accessors can be created outside SYCL kernels, which is helpful if we want to pass them as
151 * function arguments.
153 * \tparam T Type of buffer content.
154 * \tparam mode Access mode.
156 template<class T, cl::sycl::access::mode mode>
157 class DeviceAccessor : public gmx::internal::PlaceholderAccessor<T, mode>
160 // Inherit all the constructors
161 using gmx::internal::PlaceholderAccessor<T, mode>::PlaceholderAccessor;
162 //! Construct Accessor from DeviceBuffer (must be initialized)
163 DeviceAccessor(DeviceBuffer<T>& buffer) :
164 gmx::internal::PlaceholderAccessor<T, mode>(getSyclBuffer(buffer))
167 //! Construct read-only Accessor from a const DeviceBuffer (must be initialized)
168 DeviceAccessor(const DeviceBuffer<T>& buffer) :
169 gmx::internal::PlaceholderAccessor<T, mode>(getSyclBuffer(const_cast<DeviceBuffer<T>&>(buffer)))
171 /* There were some discussions about making it possible to create read-only sycl::accessor
172 * from a const sycl::buffer (https://github.com/KhronosGroup/SYCL-Docs/issues/10), but
173 * it did not make it into the SYCL2020 standard. So, we have to use const_cast above */
174 /* Using static_assert to ensure that only mode::read accessors can be created from a
175 * const DeviceBuffer. static_assert provides better error messages than std::enable_if. */
176 static_assert(mode == cl::sycl::access::mode::read,
177 "Can not create non-read-only accessor from a const DeviceBuffer");
181 //! Helper function to get sycl:buffer object from DeviceBuffer wrapper, with a sanity check.
182 static inline cl::sycl::buffer<T, 1>& getSyclBuffer(DeviceBuffer<T>& buffer)
184 GMX_ASSERT(bool(buffer), "Trying to construct accessor from an uninitialized buffer");
185 return *buffer.buffer_;
189 namespace gmx::internal
191 //! A "blackhole" class to be used when we want to ignore an argument to a function.
192 struct EmptyClassThatIgnoresConstructorArguments
194 template<class... Args>
195 [[maybe_unused]] EmptyClassThatIgnoresConstructorArguments(Args&&... /*args*/)
198 //! Allow casting to nullptr
199 constexpr operator std::nullptr_t() const { return nullptr; }
201 } // namespace gmx::internal
204 * Helper class to be used as function argument. Will either correspond to a device accessor, or an empty class.
208 template <bool doFoo>
209 void getBarKernel(handler& cgh, OptionalAccessor<float, mode::read, doFoo> a_fooPrms)
212 cgh.require(a_fooPrms);
213 // Can only use a_fooPrms if doFoo == true
216 template <bool doFoo>
217 void callBar(DeviceBuffer<float> b_fooPrms)
219 // If doFoo is false, b_fooPrms will be ignored (can be not initialized).
220 // Otherwise, an accessor will be built (b_fooPrms must be a valid buffer).
221 auto kernel = getBarKernel<doFoo>(b_fooPrms);
222 // If the accessor in not enabled, anything can be passed as its ctor argument.
223 auto kernel2 = getBarKernel<false>(nullptr_t);
227 * \tparam T Data type of the underlying buffer
228 * \tparam mode Access mode of the accessor
229 * \tparam enabled Compile-time flag indicating whether we want to actually create an accessor.
231 template<class T, cl::sycl::access::mode mode, bool enabled>
232 using OptionalAccessor =
233 std::conditional_t<enabled, DeviceAccessor<T, mode>, gmx::internal::EmptyClassThatIgnoresConstructorArguments>;
235 #endif // #ifndef DOXYGEN
237 /*! \brief Check the validity of the device buffer.
239 * Checks if the buffer is valid and if its allocation is big enough.
241 * \param[in] buffer Device buffer to be checked.
242 * \param[in] requiredSize Number of elements that the buffer will have to accommodate.
244 * \returns Whether the device buffer exists and has enough capacity.
247 static gmx_unused bool checkDeviceBuffer(const DeviceBuffer<T>& buffer, int requiredSize)
249 return buffer.buffer_ && (static_cast<int>(buffer.buffer_->get_count()) >= requiredSize);
252 /*! \libinternal \brief
253 * Allocates a device-side buffer.
254 * It is currently a caller's responsibility to call it only on not-yet allocated buffers.
256 * \tparam ValueType Raw value type of the \p buffer.
257 * \param[in,out] buffer Pointer to the device-side buffer.
258 * \param[in] numValues Number of values to accommodate.
259 * \param[in] deviceContext The buffer's device context-to-be.
261 template<typename ValueType>
262 void allocateDeviceBuffer(DeviceBuffer<ValueType>* buffer, size_t numValues, const DeviceContext& deviceContext)
264 /* SYCL does not require binding buffer to a specific context or device. The ::context_bound
265 * property only enforces the use of only given context, and possibly offers some optimizations */
266 const cl::sycl::property_list bufferProperties{ cl::sycl::property::buffer::context_bound(
267 deviceContext.context()) };
268 buffer->buffer_.reset(
269 new ClSyclBufferWrapper<ValueType>(cl::sycl::range<1>(numValues), bufferProperties));
273 * Frees a device-side buffer.
274 * This does not reset separately stored size/capacity integers,
275 * as this is planned to be a destructor of DeviceBuffer as a proper class,
276 * and no calls on \p buffer should be made afterwards.
278 * \param[in] buffer Pointer to the buffer to free.
280 template<typename ValueType>
281 void freeDeviceBuffer(DeviceBuffer<ValueType>* buffer)
283 buffer->buffer_.reset(nullptr);
287 * Performs the host-to-device data copy, synchronous or asynchronously on request.
289 * Unlike in CUDA and OpenCL, synchronous call does not guarantee that all previously
290 * submitted operations are complete, only the ones that are required for \p buffer consistency.
292 * \tparam ValueType Raw value type of the \p buffer.
293 * \param[in,out] buffer Pointer to the device-side buffer.
294 * \param[in] hostBuffer Pointer to the raw host-side memory, also typed \p ValueType.
295 * \param[in] startingOffset Offset (in values) at the device-side buffer to copy into.
296 * \param[in] numValues Number of values to copy.
297 * \param[in] deviceStream GPU stream to perform asynchronous copy in.
298 * \param[in] transferKind Copy type: synchronous or asynchronous.
299 * \param[out] timingEvent A pointer to the H2D copy timing event to be filled in.
302 template<typename ValueType>
303 void copyToDeviceBuffer(DeviceBuffer<ValueType>* buffer,
304 const ValueType* hostBuffer,
305 size_t startingOffset,
307 const DeviceStream& deviceStream,
308 GpuApiCallBehavior transferKind,
309 CommandEvent* gmx_unused timingEvent)
313 return; // such calls are actually made with empty domains
315 GMX_ASSERT(buffer, "needs a buffer pointer");
316 GMX_ASSERT(hostBuffer, "needs a host buffer pointer");
318 GMX_ASSERT(checkDeviceBuffer(*buffer, startingOffset + numValues),
319 "buffer too small or not initialized");
321 cl::sycl::buffer<ValueType>& syclBuffer = *buffer->buffer_;
323 cl::sycl::event ev = deviceStream.stream().submit([&](cl::sycl::handler& cgh) {
324 /* Here and elsewhere in this file, accessor constructor is user instead of a more common
325 * buffer::get_access, since the compiler (icpx 2021.1-beta09) occasionally gets confused
326 * by all the overloads */
327 auto d_bufferAccessor = cl::sycl::accessor<ValueType, 1, cl::sycl::access::mode::discard_write>{
328 syclBuffer, cgh, cl::sycl::range(numValues), cl::sycl::id(startingOffset)
330 cgh.copy(hostBuffer, d_bufferAccessor);
332 if (transferKind == GpuApiCallBehavior::Sync)
339 * Performs the device-to-host data copy, synchronous or asynchronously on request.
341 * Unlike in CUDA and OpenCL, synchronous call does not guarantee that all previously
342 * submitted operations are complete, only the ones that are required for \p buffer consistency.
344 * \tparam ValueType Raw value type of the \p buffer.
345 * \param[in,out] hostBuffer Pointer to the raw host-side memory, also typed \p ValueType
346 * \param[in] buffer Pointer to the device-side buffer.
347 * \param[in] startingOffset Offset (in values) at the device-side buffer to copy from.
348 * \param[in] numValues Number of values to copy.
349 * \param[in] deviceStream GPU stream to perform asynchronous copy in.
350 * \param[in] transferKind Copy type: synchronous or asynchronous.
351 * \param[out] timingEvent A pointer to the H2D copy timing event to be filled in.
354 template<typename ValueType>
355 void copyFromDeviceBuffer(ValueType* hostBuffer,
356 DeviceBuffer<ValueType>* buffer,
357 size_t startingOffset,
359 const DeviceStream& deviceStream,
360 GpuApiCallBehavior transferKind,
361 CommandEvent* gmx_unused timingEvent)
365 return; // such calls are actually made with empty domains
367 GMX_ASSERT(buffer, "needs a buffer pointer");
368 GMX_ASSERT(hostBuffer, "needs a host buffer pointer");
370 GMX_ASSERT(checkDeviceBuffer(*buffer, startingOffset + numValues),
371 "buffer too small or not initialized");
373 cl::sycl::buffer<ValueType>& syclBuffer = *buffer->buffer_;
375 cl::sycl::event ev = deviceStream.stream().submit([&](cl::sycl::handler& cgh) {
376 const auto d_bufferAccessor = cl::sycl::accessor<ValueType, 1, cl::sycl::access::mode::read>{
377 syclBuffer, cgh, cl::sycl::range(numValues), cl::sycl::id(startingOffset)
379 cgh.copy(d_bufferAccessor, hostBuffer);
381 if (transferKind == GpuApiCallBehavior::Sync)
388 * Performs the device-to-device data copy, synchronous or asynchronously on request.
390 * \tparam ValueType Raw value type of the \p buffer.
392 template<typename ValueType>
393 void copyBetweenDeviceBuffers(DeviceBuffer<ValueType>* /* destinationDeviceBuffer */,
394 DeviceBuffer<ValueType>* /* sourceDeviceBuffer */,
395 size_t /* numValues */,
396 const DeviceStream& /* deviceStream */,
397 GpuApiCallBehavior /* transferKind */,
398 CommandEvent* /*timingEvent*/)
401 gmx_fatal(FARGS, "D2D copy stub was called. Not yet implemented in SYCL.");
405 namespace gmx::internal
407 /*! \brief Helper function to clear device buffer.
409 * Not applicable to GROMACS's Float3 (a.k.a. gmx::RVec) and other custom types.
410 * From SYCL specs: "T must be a scalar value or a SYCL vector type."
412 template<typename ValueType>
413 cl::sycl::event fillSyclBufferWithNull(cl::sycl::buffer<ValueType, 1>& buffer,
414 size_t startingOffset,
416 cl::sycl::queue queue)
418 using cl::sycl::access::mode;
419 const cl::sycl::range<1> range(numValues);
420 const cl::sycl::id<1> offset(startingOffset);
421 const ValueType pattern = ValueType(0); // SYCL vectors support initialization by scalar
423 return queue.submit([&](cl::sycl::handler& cgh) {
424 auto d_bufferAccessor =
425 cl::sycl::accessor<ValueType, 1, mode::discard_write>{ buffer, cgh, range, offset };
426 cgh.fill(d_bufferAccessor, pattern);
430 //! \brief Helper function to clear device buffer of type Float3.
432 inline cl::sycl::event fillSyclBufferWithNull(cl::sycl::buffer<Float3, 1>& buffer,
433 size_t startingOffset,
435 cl::sycl::queue queue)
437 constexpr bool usingHipSycl =
445 if constexpr (usingHipSycl)
447 // hipSYCL does not support reinterpret but allows using Float3 directly.
448 using cl::sycl::access::mode;
449 const cl::sycl::range<1> range(numValues);
450 const cl::sycl::id<1> offset(startingOffset);
451 const Float3 pattern{ 0, 0, 0 };
453 return queue.submit([&](cl::sycl::handler& cgh) {
454 auto d_bufferAccessor =
455 cl::sycl::accessor<Float3, 1, mode::discard_write>{ buffer, cgh, range, offset };
456 cgh.fill(d_bufferAccessor, pattern);
459 else // When not using hipSYCL, reinterpret as a flat float array
462 cl::sycl::buffer<float, 1> bufferAsFloat = buffer.reinterpret<float, 1>(buffer.get_count() * DIM);
463 return fillSyclBufferWithNull<float>(
464 bufferAsFloat, startingOffset * DIM, numValues * DIM, std::move(queue));
469 } // namespace gmx::internal
472 * Clears the device buffer asynchronously.
474 * \tparam ValueType Raw value type of the \p buffer.
475 * \param[in,out] buffer Pointer to the device-side buffer.
476 * \param[in] startingOffset Offset (in values) at the device-side buffer to start clearing at.
477 * \param[in] numValues Number of values to clear.
478 * \param[in] deviceStream GPU stream.
480 template<typename ValueType>
481 void clearDeviceBufferAsync(DeviceBuffer<ValueType>* buffer,
482 size_t startingOffset,
484 const DeviceStream& deviceStream)
490 GMX_ASSERT(buffer, "needs a buffer pointer");
492 GMX_ASSERT(checkDeviceBuffer(*buffer, startingOffset + numValues),
493 "buffer too small or not initialized");
495 cl::sycl::buffer<ValueType>& syclBuffer = *(buffer->buffer_);
497 gmx::internal::fillSyclBufferWithNull<ValueType>(
498 syclBuffer, startingOffset, numValues, deviceStream.stream());
501 /*! \brief Create a texture object for an array of type ValueType.
503 * Creates the device buffer and copies read-only data for an array of type ValueType.
504 * Like OpenCL, does not really do anything with textures, simply creates a buffer
505 * and initializes it.
507 * \tparam ValueType Raw data type.
509 * \param[out] deviceBuffer Device buffer to store data in.
510 * \param[in] hostBuffer Host buffer to get date from.
511 * \param[in] numValues Number of elements in the buffer.
512 * \param[in] deviceContext GPU device context.
514 template<typename ValueType>
515 void initParamLookupTable(DeviceBuffer<ValueType>* deviceBuffer,
516 DeviceTexture* /* deviceTexture */,
517 const ValueType* hostBuffer,
519 const DeviceContext& deviceContext)
521 GMX_ASSERT(hostBuffer, "Host buffer should be specified.");
522 GMX_ASSERT(deviceBuffer, "Device buffer should be specified.");
524 /* Constructing buffer with cl::sycl::buffer(T* data, size_t size) will take ownership
525 * of this memory region making it unusable, which might lead to side-effects.
526 * On the other hand, cl::sycl::buffer(InputIterator<T> begin, InputIterator<T> end) will
527 * initialize the buffer without affecting ownership of the memory, although
528 * it will consume extra memory on host. */
529 const cl::sycl::property_list bufferProperties{ cl::sycl::property::buffer::context_bound(
530 deviceContext.context()) };
531 deviceBuffer->buffer_.reset(new ClSyclBufferWrapper<ValueType>(
532 hostBuffer, hostBuffer + numValues, bufferProperties));
535 /*! \brief Release the OpenCL device buffer.
537 * \tparam ValueType Raw data type.
539 * \param[in,out] deviceBuffer Device buffer to store data in.
541 template<typename ValueType>
542 void destroyParamLookupTable(DeviceBuffer<ValueType>* deviceBuffer, DeviceTexture* /* deviceTexture */)
544 deviceBuffer->buffer_.reset(nullptr);
547 #endif // GMX_GPU_UTILS_DEVICEBUFFER_SYCL_H