GpuMemUtils.cpp File Reference

#include "GpuMemUtils.h"
#include "Allocators/CudaAllocator.h"
#include "Allocators/ThrustAllocator.h"
#include "GpuInitGroups.h"
#include "Shared/Logger.h"
#include "StreamingTopN.h"
#include "../CudaMgr/CudaMgr.h"
#include "GroupByAndAggregate.h"

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Namespaces
	anonymous_namespace{GpuMemUtils.cpp}

Functions
void	copy_to_gpu (Data_Namespace::DataMgr *data_mgr, CUdeviceptr dst, const void *src, const size_t num_bytes, const int device_id)
size_t	anonymous_namespace{GpuMemUtils.cpp}::coalesced_size (const QueryMemoryDescriptor &query_mem_desc, const size_t group_by_one_buffer_size, const unsigned grid_size_x)
GpuGroupByBuffers	create_dev_group_by_buffers (DeviceAllocator *cuda_allocator, const std::vector< int64_t *> &group_by_buffers, const QueryMemoryDescriptor &query_mem_desc, const unsigned block_size_x, const unsigned grid_size_x, const int device_id, const ExecutorDispatchMode dispatch_mode, const int64_t num_input_rows, const bool prepend_index_buffer, const bool always_init_group_by_on_host, const bool use_bump_allocator, Allocator *insitu_allocator)
void	copy_from_gpu (Data_Namespace::DataMgr *data_mgr, void *dst, const CUdeviceptr src, const size_t num_bytes, const int device_id)
void	copy_group_by_buffers_from_gpu (Data_Namespace::DataMgr *data_mgr, const std::vector< int64_t *> &group_by_buffers, const size_t groups_buffer_size, const CUdeviceptr group_by_dev_buffers_mem, const QueryMemoryDescriptor &query_mem_desc, const unsigned block_size_x, const unsigned grid_size_x, const int device_id, const bool prepend_index_buffer)
size_t	get_num_allocated_rows_from_gpu (Data_Namespace::DataMgr *data_mgr, CUdeviceptr projection_size_gpu, const int device_id)
void	copy_projection_buffer_from_gpu_columnar (Data_Namespace::DataMgr *data_mgr, const GpuGroupByBuffers &gpu_group_by_buffers, const QueryMemoryDescriptor &query_mem_desc, int8_t *projection_buffer, const size_t projection_count, const int device_id)

Variables
size_t	g_max_memory_allocation_size
size_t	g_min_memory_allocation_size
double	g_bump_allocator_step_reduction

Function Documentation

copy_from_gpu()

void copy_from_gpu	(	Data_Namespace::DataMgr *	data_mgr,
		void *	dst,
		const CUdeviceptr	src,
		const size_t	num_bytes,
		const int	device_id
	)

Definition at line 211 of file GpuMemUtils.cpp.

References CHECK, and Data_Namespace::DataMgr::getCudaMgr().

Referenced by OverlapsJoinHashTable::approximateTupleCount(), BaselineJoinHashTable::approximateTupleCount(), OverlapsJoinHashTable::computeBucketSizes(), copy_group_by_buffers_from_gpu(), copy_projection_buffer_from_gpu_columnar(), anonymous_namespace{ResultSetIteration.cpp}::fetch_data_from_gpu(), get_num_allocated_rows_from_gpu(), ResultSet::getVarlenOrderEntry(), OverlapsJoinHashTable::initHashTableOnGpu(), BaselineJoinHashTable::initHashTableOnGpu(), JoinHashTable::initOneToOneHashTable(), QueryExecutionContext::launchGpuCode(), ResultSet::makeVarlenTargetValue(), ResultSet::syncEstimatorBuffer(), BaselineJoinHashTable::toSet(), JoinHashTable::toSet(), BaselineJoinHashTable::toString(), and JoinHashTable::toString().

                                        {
  const auto cuda_mgr = data_mgr->getCudaMgr();
  CHECK(cuda_mgr);
  cuda_mgr->copyDeviceToHost(static_cast<int8_t*>(dst),
                             reinterpret_cast<const int8_t*>(src),
                             num_bytes,
                             device_id);
}

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copy_group_by_buffers_from_gpu()

void copy_group_by_buffers_from_gpu	(	Data_Namespace::DataMgr *	data_mgr,
		const std::vector< int64_t *> &	group_by_buffers,
		const size_t	groups_buffer_size,
		const CUdeviceptr	group_by_dev_buffers_mem,
		const QueryMemoryDescriptor &	query_mem_desc,
		const unsigned	block_size_x,
		const unsigned	grid_size_x,
		const int	device_id,
		const bool	prepend_index_buffer
	)

Definition at line 224 of file GpuMemUtils.cpp.

References QueryMemoryDescriptor::blocksShareMemory(), CHECK_EQ, CHECK_LT, anonymous_namespace{GpuMemUtils.cpp}::coalesced_size(), copy_from_gpu(), QueryMemoryDescriptor::getEntryCount(), and groups_buffer_size.

Referenced by QueryMemoryInitializer::copyGroupByBuffersFromGpu(), and ResultSet::radixSortOnGpu().

                                                                     {
  if (group_by_buffers.empty()) {
    return;
  }
  const unsigned block_buffer_count{query_mem_desc.blocksShareMemory() ? 1 : grid_size_x};
  if (block_buffer_count == 1 && !prepend_index_buffer) {
    CHECK_EQ(coalesced_size(query_mem_desc, groups_buffer_size, block_buffer_count),
             groups_buffer_size);
    copy_from_gpu(data_mgr,
                  group_by_buffers[0],
                  group_by_dev_buffers_mem,
                  groups_buffer_size,
                  device_id);
    return;
  }
  const size_t index_buffer_sz{
      prepend_index_buffer ? query_mem_desc.getEntryCount() * sizeof(int64_t) : 0};
  std::vector<int8_t> buff_from_gpu(
      coalesced_size(query_mem_desc, groups_buffer_size, block_buffer_count) +
      index_buffer_sz);
  copy_from_gpu(data_mgr,
                &buff_from_gpu[0],
                group_by_dev_buffers_mem - index_buffer_sz,
                buff_from_gpu.size(),
                device_id);
  auto buff_from_gpu_ptr = &buff_from_gpu[0];
  for (size_t i = 0; i < block_buffer_count; ++i) {
    CHECK_LT(i * block_size_x, group_by_buffers.size());
    memcpy(group_by_buffers[i * block_size_x],
           buff_from_gpu_ptr,
           groups_buffer_size + index_buffer_sz);
    buff_from_gpu_ptr += groups_buffer_size;
  }
}

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copy_projection_buffer_from_gpu_columnar()

void copy_projection_buffer_from_gpu_columnar	(	Data_Namespace::DataMgr *	data_mgr,
		const GpuGroupByBuffers &	gpu_group_by_buffers,
		const QueryMemoryDescriptor &	query_mem_desc,
		int8_t *	projection_buffer,
		const size_t	projection_count,
		const int	device_id
	)

For projection queries we only copy back as many elements as necessary, not the whole output buffer. The goal is to be able to build a compact ResultSet, particularly useful for columnar outputs.

NOTE: Saman: we should revisit this function when we have a bump allocator

Definition at line 289 of file GpuMemUtils.cpp.

References align_to_int64(), CHECK, copy_from_gpu(), QueryMemoryDescriptor::didOutputColumnar(), QueryMemoryDescriptor::getColOffInBytes(), QueryMemoryDescriptor::getPaddedSlotWidthBytes(), QueryMemoryDescriptor::getQueryDescriptionType(), QueryMemoryDescriptor::getSlotCount(), Projection, and GpuGroupByBuffers::second.

Referenced by QueryMemoryInitializer::compactProjectionBuffersGpu().

                         {
  CHECK(query_mem_desc.didOutputColumnar());
  CHECK(query_mem_desc.getQueryDescriptionType() == QueryDescriptionType::Projection);
  constexpr size_t row_index_width = sizeof(int64_t);
  // copy all the row indices back to the host
  copy_from_gpu(data_mgr,
                reinterpret_cast<int64_t*>(projection_buffer),
                gpu_group_by_buffers.second,
                projection_count * row_index_width,
                device_id);
  size_t buffer_offset_cpu{projection_count * row_index_width};
  // other columns are actual non-lazy columns for the projection:
  for (size_t i = 0; i < query_mem_desc.getSlotCount(); i++) {
    if (query_mem_desc.getPaddedSlotWidthBytes(i) > 0) {
      const auto column_proj_size =
          projection_count * query_mem_desc.getPaddedSlotWidthBytes(i);
      copy_from_gpu(data_mgr,
                    projection_buffer + buffer_offset_cpu,
                    gpu_group_by_buffers.second + query_mem_desc.getColOffInBytes(i),
                    column_proj_size,
                    device_id);
      buffer_offset_cpu += align_to_int64(column_proj_size);
    }
  }
}

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copy_to_gpu()

void copy_to_gpu	(	Data_Namespace::DataMgr *	data_mgr,
		CUdeviceptr	dst,
		const void *	src,
		const size_t	num_bytes,
		const int	device_id
	)

Definition at line 31 of file GpuMemUtils.cpp.

References CHECK, and Data_Namespace::DataMgr::getCudaMgr().

Referenced by OverlapsJoinHashTable::approximateTupleCount(), JoinHashTableInterface::fetchJoinColumn(), ColumnFetcher::getOneTableColumnFragment(), BaselineJoinHashTable::initHashTableForDevice(), OverlapsJoinHashTable::initHashTableOnGpu(), BaselineJoinHashTable::initHashTableOnGpu(), JoinHashTable::initOneToManyHashTable(), JoinHashTable::initOneToOneHashTable(), InValuesBitmap::InValuesBitmap(), QueryExecutionContext::launchCpuCode(), QueryExecutionContext::launchGpuCode(), transfer_flat_object_to_gpu(), transfer_vector_of_flat_objects_to_gpu(), and ColumnFetcher::transferColumnIfNeeded().

                                      {
#ifdef HAVE_CUDA
  if (!data_mgr) {  // only for unit tests
    cuMemcpyHtoD(dst, src, num_bytes);
    return;
  }
#endif  // HAVE_CUDA
  const auto cuda_mgr = data_mgr->getCudaMgr();
  CHECK(cuda_mgr);
  cuda_mgr->copyHostToDevice(reinterpret_cast<int8_t*>(dst),
                             static_cast<const int8_t*>(src),
                             num_bytes,
                             device_id);
}

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create_dev_group_by_buffers()

GpuGroupByBuffers create_dev_group_by_buffers	(	DeviceAllocator *	cuda_allocator,
		const std::vector< int64_t *> &	group_by_buffers,
		const QueryMemoryDescriptor &	query_mem_desc,
		const unsigned	block_size_x,
		const unsigned	grid_size_x,
		const int	device_id,
		const ExecutorDispatchMode	dispatch_mode,
		const int64_t	num_input_rows,
		const bool	prepend_index_buffer,
		const bool	always_init_group_by_on_host,
		const bool	use_bump_allocator,
		Allocator *	insitu_allocator
	)

Definition at line 61 of file GpuMemUtils.cpp.

References align_to_int64(), Allocator::alloc(), QueryMemoryDescriptor::blocksShareMemory(), CHECK, CHECK_GT, CHECK_LE, anonymous_namespace{GpuMemUtils.cpp}::coalesced_size(), DeviceAllocator::copyToDevice(), g_bump_allocator_step_reduction, g_max_memory_allocation_size, g_min_memory_allocation_size, QueryMemoryDescriptor::getBufferSizeBytes(), QueryMemoryDescriptor::getEntryCount(), QueryMemoryDescriptor::getRowSize(), GPU, groups_buffer_size, logger::INFO, KernelPerFragment, QueryMemoryDescriptor::lazyInitGroups(), LOG, QueryMemoryDescriptor::threadsShareMemory(), to_string(), and logger::WARNING.

Referenced by QueryMemoryInitializer::allocateCountDistinctSet(), and ResultSet::radixSortOnGpu().

                                 {
  if (group_by_buffers.empty() && !insitu_allocator) {
    return {0, 0, 0};
  }
  CHECK(cuda_allocator);

  size_t groups_buffer_size{0};
  CUdeviceptr group_by_dev_buffers_mem{0};
  size_t mem_size{0};
  size_t entry_count{0};

  if (use_bump_allocator) {
    CHECK(!prepend_index_buffer);
    CHECK(!insitu_allocator);

    if (dispatch_mode == ExecutorDispatchMode::KernelPerFragment) {
      // Allocate an output buffer equal to the size of the number of rows in the
      // fragment. The kernel per fragment path is only used for projections with lazy
      // fetched outputs. Therefore, the resulting output buffer should be relatively
      // narrow compared to the width of an input row, offsetting the larger allocation.

      CHECK_GT(num_input_rows, int64_t(0));
      entry_count = num_input_rows;
      groups_buffer_size =
          query_mem_desc.getBufferSizeBytes(ExecutorDeviceType::GPU, entry_count);
      mem_size = coalesced_size(query_mem_desc,
                                groups_buffer_size,
                                query_mem_desc.blocksShareMemory() ? 1 : grid_size_x);
      // TODO(adb): render allocator support
      group_by_dev_buffers_mem =
          reinterpret_cast<CUdeviceptr>(cuda_allocator->alloc(mem_size));
    } else {
      // Attempt to allocate increasingly small buffers until we have less than 256B of
      // memory remaining on the device. This may have the side effect of evicting
      // memory allocated for previous queries. However, at current maximum slab sizes
      // (2GB) we expect these effects to be minimal.
      size_t max_memory_size{g_max_memory_allocation_size};
      while (true) {
        entry_count = max_memory_size / query_mem_desc.getRowSize();
        groups_buffer_size =
            query_mem_desc.getBufferSizeBytes(ExecutorDeviceType::GPU, entry_count);

        try {
          mem_size = coalesced_size(query_mem_desc,
                                    groups_buffer_size,
                                    query_mem_desc.blocksShareMemory() ? 1 : grid_size_x);
          CHECK_LE(entry_count, std::numeric_limits<uint32_t>::max());

          // TODO(adb): render allocator support
          group_by_dev_buffers_mem =
              reinterpret_cast<CUdeviceptr>(cuda_allocator->alloc(mem_size));
        } catch (const OutOfMemory& e) {
          LOG(WARNING) << e.what();
          max_memory_size = max_memory_size * g_bump_allocator_step_reduction;
          if (max_memory_size < g_min_memory_allocation_size) {
            throw;
          }

          LOG(WARNING) << "Ran out of memory for projection query output. Retrying with "
                       << std::to_string(max_memory_size) << " bytes";

          continue;
        }
        break;
      }
    }
    LOG(INFO) << "Projection query allocation succeeded with " << groups_buffer_size
              << " bytes allocated (max entry count " << entry_count << ")";
  } else {
    entry_count = query_mem_desc.getEntryCount();
    CHECK_GT(entry_count, size_t(0));
    groups_buffer_size =
        query_mem_desc.getBufferSizeBytes(ExecutorDeviceType::GPU, entry_count);
    mem_size = coalesced_size(query_mem_desc,
                              groups_buffer_size,
                              query_mem_desc.blocksShareMemory() ? 1 : grid_size_x);
    const size_t prepended_buff_size{
        prepend_index_buffer ? align_to_int64(entry_count * sizeof(int32_t)) : 0};

    int8_t* group_by_dev_buffers_allocation{nullptr};
    if (insitu_allocator) {
      group_by_dev_buffers_allocation =
          insitu_allocator->alloc(mem_size + prepended_buff_size);
    } else {
      group_by_dev_buffers_allocation =
          cuda_allocator->alloc(mem_size + prepended_buff_size);
    }
    CHECK(group_by_dev_buffers_allocation);

    group_by_dev_buffers_mem =
        reinterpret_cast<CUdeviceptr>(group_by_dev_buffers_allocation) +
        prepended_buff_size;
  }
  CHECK_GT(groups_buffer_size, size_t(0));
  CHECK(group_by_dev_buffers_mem);

  CHECK(query_mem_desc.threadsShareMemory());
  const size_t step{block_size_x};

  if (!insitu_allocator && (always_init_group_by_on_host ||
                            !query_mem_desc.lazyInitGroups(ExecutorDeviceType::GPU))) {
    std::vector<int8_t> buff_to_gpu(mem_size);
    auto buff_to_gpu_ptr = buff_to_gpu.data();

    for (size_t i = 0; i < group_by_buffers.size(); i += step) {
      memcpy(buff_to_gpu_ptr, group_by_buffers[i], groups_buffer_size);
      buff_to_gpu_ptr += groups_buffer_size;
    }
    cuda_allocator->copyToDevice(reinterpret_cast<int8_t*>(group_by_dev_buffers_mem),
                                 buff_to_gpu.data(),
                                 buff_to_gpu.size());
  }

  auto group_by_dev_buffer = group_by_dev_buffers_mem;

  const size_t num_ptrs{block_size_x * grid_size_x};

  std::vector<CUdeviceptr> group_by_dev_buffers(num_ptrs);

  for (size_t i = 0; i < num_ptrs; i += step) {
    for (size_t j = 0; j < step; ++j) {
      group_by_dev_buffers[i + j] = group_by_dev_buffer;
    }
    if (!query_mem_desc.blocksShareMemory()) {
      group_by_dev_buffer += groups_buffer_size;
    }
  }

  auto group_by_dev_ptr = cuda_allocator->alloc(num_ptrs * sizeof(CUdeviceptr));
  cuda_allocator->copyToDevice(group_by_dev_ptr,
                               reinterpret_cast<int8_t*>(group_by_dev_buffers.data()),
                               num_ptrs * sizeof(CUdeviceptr));

  return {reinterpret_cast<CUdeviceptr>(group_by_dev_ptr),
          group_by_dev_buffers_mem,
          entry_count};
}

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get_num_allocated_rows_from_gpu()

size_t get_num_allocated_rows_from_gpu	(	Data_Namespace::DataMgr *	data_mgr,
		CUdeviceptr	projection_size_gpu,
		const int	device_id
	)

Returns back total number of allocated rows per device (i.e., number of matched elements in projections).

TODO(Saman): revisit this for bump allocators

Definition at line 273 of file GpuMemUtils.cpp.

References CHECK, copy_from_gpu(), and num_rows.

Referenced by QueryExecutionContext::launchGpuCode().

                                                            {
  int32_t num_rows{0};
  copy_from_gpu(data_mgr, &num_rows, projection_size_gpu, sizeof(num_rows), device_id);
  CHECK(num_rows >= 0);
  return static_cast<size_t>(num_rows);
}

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Variable Documentation

g_bump_allocator_step_reduction

double g_bump_allocator_step_reduction

Definition at line 104 of file Execute.cpp.

Referenced by create_dev_group_by_buffers().

g_max_memory_allocation_size

size_t g_max_memory_allocation_size

Definition at line 99 of file Execute.cpp.

Referenced by create_dev_group_by_buffers().

g_min_memory_allocation_size

size_t g_min_memory_allocation_size

Definition at line 100 of file Execute.cpp.

Referenced by create_dev_group_by_buffers().