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astaroth/src/core/kernels/reduce_PLACEHOLDER.cuh

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/*
Copyright (C) 2014-2019, Johannes Pekkilae, Miikka Vaeisalae.
This file is part of Astaroth.
Astaroth is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Astaroth is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Astaroth. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @file
* \brief Brief info.
*
* Detailed info.
*
*/
#pragma once
#include "device_globals.cuh"
#include "src/core/errchk.h"
#include "src/core/math_utils.h"
// Function pointer definitions
typedef AcReal (*ReduceFunc)(const AcReal&, const AcReal&);
typedef AcReal (*ReduceInitialScalFunc)(const AcReal&);
typedef AcReal (*ReduceInitialVecFunc)(const AcReal&, const AcReal&,
const AcReal&);
// clang-format off
/* Comparison funcs */
__device__ inline AcReal
_device_max(const AcReal& a, const AcReal& b) { return a > b ? a : b; }
__device__ inline AcReal
_device_min(const AcReal& a, const AcReal& b) { return a < b ? a : b; }
__device__ inline AcReal
_device_sum(const AcReal& a, const AcReal& b) { return a + b; }
/* Function used to determine the values used during reduction */
__device__ inline AcReal
_device_length_scal(const AcReal& a) { return AcReal(a); }
__device__ inline AcReal
_device_squared_scal(const AcReal& a) { return (AcReal)(a*a); }
__device__ inline AcReal
_device_exp_squared_scal(const AcReal& a) { return exp(a)*exp(a); }
__device__ inline AcReal
_device_length_vec(const AcReal& a, const AcReal& b, const AcReal& c) { return sqrt(a*a + b*b + c*c); }
__device__ inline AcReal
_device_squared_vec(const AcReal& a, const AcReal& b, const AcReal& c) { return _device_squared_scal(a) + _device_squared_scal(b) + _device_squared_scal(c); }
__device__ inline AcReal
_device_exp_squared_vec(const AcReal& a, const AcReal& b, const AcReal& c) { return _device_exp_squared_scal(a) + _device_exp_squared_scal(b) + _device_exp_squared_scal(c); }
// clang-format on
__device__ inline bool
oob(const int& i, const int& j, const int& k)
{
if (i >= d_mesh_info.int_params[AC_nx] ||
j >= d_mesh_info.int_params[AC_ny] ||
k >= d_mesh_info.int_params[AC_nz])
return true;
else
return false;
}
template <ReduceInitialScalFunc reduce_initial>
__global__ void
_kernel_reduce_scal(const __restrict__ AcReal* src, AcReal* dst)
{
const int i = threadIdx.x + blockIdx.x * blockDim.x;
const int j = threadIdx.y + blockIdx.y * blockDim.y;
const int k = threadIdx.z + blockIdx.z * blockDim.z;
if (oob(i, j, k))
return;
const int src_idx = DEVICE_VTXBUF_IDX(
i + d_mesh_info.int_params[AC_nx_min],
j + d_mesh_info.int_params[AC_ny_min],
k + d_mesh_info.int_params[AC_nz_min]);
const int dst_idx = DEVICE_1D_COMPDOMAIN_IDX(i, j, k);
dst[dst_idx] = reduce_initial(src[src_idx]);
}
template <ReduceInitialVecFunc reduce_initial>
__global__ void
_kernel_reduce_vec(const __restrict__ AcReal* src_a,
const __restrict__ AcReal* src_b,
const __restrict__ AcReal* src_c, AcReal* dst)
{
const int i = threadIdx.x + blockIdx.x * blockDim.x;
const int j = threadIdx.y + blockIdx.y * blockDim.y;
const int k = threadIdx.z + blockIdx.z * blockDim.z;
if (oob(i, j, k))
return;
const int src_idx = DEVICE_VTXBUF_IDX(
i + d_mesh_info.int_params[AC_nx_min],
j + d_mesh_info.int_params[AC_ny_min],
k + d_mesh_info.int_params[AC_nz_min]);
const int dst_idx = DEVICE_1D_COMPDOMAIN_IDX(i, j, k);
dst[dst_idx] = reduce_initial(src_a[src_idx], src_b[src_idx],
src_c[src_idx]);
}
///////////////////////////////////////////////////////////////////////////////
#define BLOCK_SIZE (1024)
#define ELEMS_PER_THREAD (32)
template <ReduceFunc reduce>
__global__ void
_kernel_reduce(AcReal* src, AcReal* result)
{
const int idx = threadIdx.x + blockIdx.x * BLOCK_SIZE * ELEMS_PER_THREAD;
const int scratchpad_size = DCONST_INT(AC_nxyz);
if (idx >= scratchpad_size)
return;
__shared__ AcReal smem[BLOCK_SIZE];
AcReal tmp = src[idx];
for (int i = 1; i < ELEMS_PER_THREAD; ++i) {
const int src_idx = idx + i * BLOCK_SIZE;
if (src_idx >= scratchpad_size) {
// This check is for safety: if accessing uninitialized values
// beyond the mesh boundaries, we will immediately start seeing NANs
if (threadIdx.x < BLOCK_SIZE)
smem[threadIdx.x] = NAN;
else
break;
}
tmp = reduce(tmp, src[src_idx]);
}
smem[threadIdx.x] = tmp;
__syncthreads();
int offset = BLOCK_SIZE / 2;
while (offset > 0) {
if (threadIdx.x < offset) {
tmp = reduce(tmp, smem[threadIdx.x + offset]);
smem[threadIdx.x] = tmp;
}
offset /= 2;
__syncthreads();
}
if (threadIdx.x == 0)
src[idx] = tmp;
}
template <ReduceFunc reduce>
__global__ void
_kernel_reduce_block(const __restrict__ AcReal* src, AcReal* result)
{
const int scratchpad_size = DCONST_INT(AC_nxyz);
const int idx = threadIdx.x + blockIdx.x * BLOCK_SIZE * ELEMS_PER_THREAD;
AcReal tmp = src[idx];
const int block_offset = BLOCK_SIZE * ELEMS_PER_THREAD;
for (int i = 1; idx + i * block_offset < scratchpad_size; ++i)
tmp = reduce(tmp, src[idx + i * block_offset]);
*result = tmp;
}
//////////////////////////////////////////////////////////////////////////////
AcReal
_reduce_scal(const cudaStream_t stream,
const ReductionType& rtype, const int& nx, const int& ny,
const int& nz, const AcReal* vertex_buffer,
AcReal* reduce_scratchpad, AcReal* reduce_result)
{
bool solve_mean = false;
const dim3 tpb(32, 4, 1);
const dim3 bpg(int(ceil(AcReal(nx) / tpb.x)), int(ceil(AcReal(ny) / tpb.y)),
int(ceil(AcReal(nz) / tpb.z)));
const int scratchpad_size = nx * ny * nz;
const int bpg2 = (unsigned int)ceil(AcReal(scratchpad_size) /
AcReal(ELEMS_PER_THREAD * BLOCK_SIZE));
switch (rtype) {
case RTYPE_MAX:
_kernel_reduce_scal<_device_length_scal>
<<<bpg, tpb, 0, stream>>>(vertex_buffer, reduce_scratchpad);
_kernel_reduce<_device_max>
<<<bpg2, BLOCK_SIZE, 0, stream>>>(reduce_scratchpad, reduce_result);
_kernel_reduce_block<_device_max>
<<<1, 1, 0, stream>>>(reduce_scratchpad, reduce_result);
break;
case RTYPE_MIN:
_kernel_reduce_scal<_device_length_scal>
<<<bpg, tpb, 0, stream>>>(vertex_buffer, reduce_scratchpad);
_kernel_reduce<_device_min>
<<<bpg2, BLOCK_SIZE, 0, stream>>>(reduce_scratchpad, reduce_result);
_kernel_reduce_block<_device_min>
<<<1, 1, 0, stream>>>(reduce_scratchpad, reduce_result);
break;
case RTYPE_RMS:
_kernel_reduce_scal<_device_squared_scal>
<<<bpg, tpb, 0, stream>>>(vertex_buffer, reduce_scratchpad);
_kernel_reduce<_device_sum>
<<<bpg2, BLOCK_SIZE, 0, stream>>>(reduce_scratchpad, reduce_result);
_kernel_reduce_block<_device_sum>
<<<1, 1, 0, stream>>>(reduce_scratchpad, reduce_result);
solve_mean = true;
break;
case RTYPE_RMS_EXP:
_kernel_reduce_scal<_device_exp_squared_scal>
<<<bpg, tpb, 0, stream>>>(vertex_buffer, reduce_scratchpad);
_kernel_reduce<_device_sum>
<<<bpg2, BLOCK_SIZE, 0, stream>>>(reduce_scratchpad, reduce_result);
_kernel_reduce_block<_device_sum>
<<<1, 1, 0, stream>>>(reduce_scratchpad, reduce_result);
solve_mean = true;
break;
default:
ERROR("Unrecognized RTYPE");
}
AcReal result;
cudaMemcpy(&result, reduce_result, sizeof(AcReal), cudaMemcpyDeviceToHost);
if (solve_mean) {
const AcReal inv_n = AcReal(1.0) / (nx * ny * nz);
return inv_n * result;
}
else {
return result;
}
}
AcReal
_reduce_vec(const cudaStream_t stream,
const ReductionType& rtype, const int& nx, const int& ny,
const int& nz, const AcReal* vertex_buffer_a,
const AcReal* vertex_buffer_b, const AcReal* vertex_buffer_c,
AcReal* reduce_scratchpad, AcReal* reduce_result)
{
bool solve_mean = false;
const dim3 tpb(32, 4, 1);
const dim3 bpg(int(ceil(float(nx) / tpb.x)),
int(ceil(float(ny) / tpb.y)),
int(ceil(float(nz) / tpb.z)));
const int scratchpad_size = nx * ny * nz;
const int bpg2 = (unsigned int)ceil(float(scratchpad_size) /
float(ELEMS_PER_THREAD * BLOCK_SIZE));
// "Features" of this quick & efficient reduction:
// Block size must be smaller than the computational domain size
// (otherwise we would have do some additional bounds checking in the
// second half of _kernel_reduce, which gets quite confusing)
// Also the BLOCK_SIZE must be a multiple of two s.t. we can easily split
// the work without worrying too much about the array bounds.
ERRCHK(BLOCK_SIZE <= scratchpad_size);
ERRCHK(!(BLOCK_SIZE % 2));
// NOTE! Also does not work properly with non-power of two mesh dimension
// Issue is with "smem[BLOCK_SIZE];". If you init smem to NANs, you can
// see that uninitialized smem values are used in the comparison
ERRCHK(is_power_of_two(nx));
ERRCHK(is_power_of_two(ny));
ERRCHK(is_power_of_two(nz));
switch (rtype) {
case RTYPE_MAX:
_kernel_reduce_vec<_device_length_vec>
<<<bpg, tpb, 0, stream>>>(vertex_buffer_a, vertex_buffer_b, vertex_buffer_c,
reduce_scratchpad);
_kernel_reduce<_device_max>
<<<bpg2, BLOCK_SIZE, 0, stream>>>(reduce_scratchpad, reduce_result);
_kernel_reduce_block<_device_max>
<<<1, 1, 0, stream>>>(reduce_scratchpad, reduce_result);
break;
case RTYPE_MIN:
_kernel_reduce_vec<_device_length_vec>
<<<bpg, tpb, 0, stream>>>(vertex_buffer_a, vertex_buffer_b, vertex_buffer_c,
reduce_scratchpad);
_kernel_reduce<_device_min>
<<<bpg2, BLOCK_SIZE, 0, stream>>>(reduce_scratchpad, reduce_result);
_kernel_reduce_block<_device_min>
<<<1, 1, 0, stream>>>(reduce_scratchpad, reduce_result);
break;
case RTYPE_RMS:
_kernel_reduce_vec<_device_squared_vec>
<<<bpg, tpb, 0, stream>>>(vertex_buffer_a, vertex_buffer_b, vertex_buffer_c,
reduce_scratchpad);
_kernel_reduce<_device_sum>
<<<bpg2, BLOCK_SIZE, 0, stream>>>(reduce_scratchpad, reduce_result);
_kernel_reduce_block<_device_sum>
<<<1, 1, 0, stream>>>(reduce_scratchpad, reduce_result);
solve_mean = true;
break;
case RTYPE_RMS_EXP:
_kernel_reduce_vec<_device_exp_squared_vec>
<<<bpg, tpb, 0, stream>>>(vertex_buffer_a, vertex_buffer_b, vertex_buffer_c,
reduce_scratchpad);
_kernel_reduce<_device_sum>
<<<bpg2, BLOCK_SIZE, 0, stream>>>(reduce_scratchpad, reduce_result);
_kernel_reduce_block<_device_sum>
<<<1, 1, 0, stream>>>(reduce_scratchpad, reduce_result);
solve_mean = true;
break;
default:
ERROR("Unrecognized RTYPE");
}
AcReal result;
cudaMemcpy(&result, reduce_result, sizeof(AcReal), cudaMemcpyDeviceToHost);
if (solve_mean) {
const AcReal inv_n = AcReal(1.0) / (nx * ny * nz);
return inv_n * result;
}
else {
return result;
}
}