1 files changed, 52 insertions, 0 deletions
diff --git a/intern/cycles/kernel/device/gpu/work_stealing.h b/intern/cycles/kernel/device/gpu/work_stealing.h
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index 00000000000..fab0915c38e
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+++ b/intern/cycles/kernel/device/gpu/work_stealing.h
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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.
+ */
+
+#pragma once
+
+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 KernelWorkTile *tile,
+                                      uint global_work_index,
+                                      ccl_private uint *x,
+                                      ccl_private uint *y,
+                                      ccl_private uint *sample)
+{
+#if 0
+  /* Keep threads for the same sample together. */
+  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;
+#else
+  /* Keeping threads for the same pixel together.
+   * Appears to improve performance by a few % on CUDA and OptiX. */
+  uint sample_offset = global_work_index % tile->num_samples;
+  uint pixel_offset = global_work_index / tile->num_samples;
+#endif
+
+  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;
+}
+
+CCL_NAMESPACE_END