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/*
* Copyright 2011-2015 Blender Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef __KERNEL_WORK_STEALING_H__
#define __KERNEL_WORK_STEALING_H__
CCL_NAMESPACE_BEGIN
/*
* Utility functions for work stealing
*/
/* Map global work index to tile, pixel X/Y and sample. */
ccl_device_inline void get_work_pixel(ccl_global const WorkTile *tile,
uint global_work_index,
ccl_private uint *x,
ccl_private uint *y,
ccl_private uint *sample)
{
#ifdef __KERNEL_CUDA__
/* Keeping threads for the same pixel together improves performance on CUDA. */
uint sample_offset = global_work_index % tile->num_samples;
uint pixel_offset = global_work_index / tile->num_samples;
#else /* __KERNEL_CUDA__ */
uint tile_pixels = tile->w * tile->h;
uint sample_offset = global_work_index / tile_pixels;
uint pixel_offset = global_work_index - sample_offset * tile_pixels;
#endif /* __KERNEL_CUDA__ */
uint y_offset = pixel_offset / tile->w;
uint x_offset = pixel_offset - y_offset * tile->w;
*x = tile->x + x_offset;
*y = tile->y + y_offset;
*sample = tile->start_sample + sample_offset;
}
#ifdef __KERNEL_OPENCL__
# pragma OPENCL EXTENSION cl_khr_global_int32_base_atomics : enable
#endif
#ifdef __SPLIT_KERNEL__
/* Returns true if there is work */
ccl_device bool get_next_work_item(KernelGlobals *kg,
ccl_global uint *work_pools,
uint total_work_size,
uint ray_index,
ccl_private uint *global_work_index)
{
/* With a small amount of work there may be more threads than work due to
* rounding up of global size, stop such threads immediately. */
if (ray_index >= total_work_size) {
return false;
}
/* Increase atomic work index counter in pool. */
uint pool = ray_index / WORK_POOL_SIZE;
uint work_index = atomic_fetch_and_inc_uint32(&work_pools[pool]);
/* Map per-pool work index to a global work index. */
uint global_size = ccl_global_size(0) * ccl_global_size(1);
kernel_assert(global_size % WORK_POOL_SIZE == 0);
kernel_assert(ray_index < global_size);
*global_work_index = (work_index / WORK_POOL_SIZE) * global_size + (pool * WORK_POOL_SIZE) +
(work_index % WORK_POOL_SIZE);
/* Test if all work for this pool is done. */
return (*global_work_index < total_work_size);
}
ccl_device bool get_next_work(KernelGlobals *kg,
ccl_global uint *work_pools,
uint total_work_size,
uint ray_index,
ccl_private uint *global_work_index)
{
bool got_work = false;
if (kernel_data.film.pass_adaptive_aux_buffer) {
do {
got_work = get_next_work_item(kg, work_pools, total_work_size, ray_index, global_work_index);
if (got_work) {
ccl_global WorkTile *tile = &kernel_split_params.tile;
uint x, y, sample;
get_work_pixel(tile, *global_work_index, &x, &y, &sample);
uint buffer_offset = (tile->offset + x + y * tile->stride) * kernel_data.film.pass_stride;
ccl_global float *buffer = kernel_split_params.tile.buffer + buffer_offset;
ccl_global float4 *aux = (ccl_global float4 *)(buffer +
kernel_data.film.pass_adaptive_aux_buffer);
if ((*aux).w == 0.0f) {
break;
}
}
} while (got_work);
}
else {
got_work = get_next_work_item(kg, work_pools, total_work_size, ray_index, global_work_index);
}
return got_work;
}
#endif
CCL_NAMESPACE_END
#endif /* __KERNEL_WORK_STEALING_H__ */
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