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Cycles: Use stack storage for temporary data on leaf creation

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Uses new StackAllocator from util_stack_allocator. Some tweaks to the stack
storage size are possible, read notes in the code about this.

At this point we might want to rename allocator files to util_allocator_foo.c,
so the stay nicely grouped in the folder.
This commit is contained in:
Sergey Sharybin 2016-02-21 15:22:48 +01:00
parent ffe59c54cb
commit 9c420e5e48
1 changed files with 20 additions and 5 deletions
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25
intern/cycles/bvh/bvh_build.cpp
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@ -30,6 +30,7 @@
#include "util_foreach.h"
#include "util_logging.h"
#include "util_progress.h"
#include "util_stack_allocator.h"
#include "util_time.h"
CCL_NAMESPACE_BEGIN
@ -481,12 +482,26 @@ BVHNode *BVHBuild::create_primitive_leaf_node(const int *p_type,
BVHNode* BVHBuild::create_leaf_node(const BVHRange& range)
{
/* TODO(sergey): Consider writing own allocator which would
* not do heap allocation if number of elements is relatively small.
const int MAX_ITEMS_PER_LEAF = 16;
/* This is a bit overallocating here (considering leaf size into account),
* but chunk-based re-allocation in vector makes it difficult to use small
* size of stack storage here. Some tweaks are possible tho.
*
* NOTES:
* - If the size is too big, we'll have inefficient stack usage,
* and lots of cache misses.
* - If the size is too small, then we can run out of memory
* allowed to be used by vector.
* - Optimistic re-allocation in STL could jump us out of stack usage
* because re-allocation happens in chunks and size of those chunks we
* can not control.
*/
vector<int> p_type[PRIMITIVE_NUM_TOTAL];
vector<int> p_index[PRIMITIVE_NUM_TOTAL];
vector<int> p_object[PRIMITIVE_NUM_TOTAL];
typedef StackAllocator<MAX_ITEMS_PER_LEAF * 8, int> LeafStackAllocator;
vector<int, LeafStackAllocator> p_type[PRIMITIVE_NUM_TOTAL];
vector<int, LeafStackAllocator> p_index[PRIMITIVE_NUM_TOTAL];
vector<int, LeafStackAllocator> p_object[PRIMITIVE_NUM_TOTAL];
uint visibility[PRIMITIVE_NUM_TOTAL] = {0};
/* NOTE: Keep initializtion in sync with actual number of primitives. */
BoundBox bounds[PRIMITIVE_NUM_TOTAL] = {BoundBox::empty,