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parallelization is starting to work

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Wenzel Jakob 2010-10-11 15:53:59 +02:00
parent 2d5eff417c
commit db444cd87f
2 changed files with 157 additions and 48 deletions
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191
include/mitsuba/render/gkdtree.h
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@ -30,7 +30,7 @@
#define MTS_KD_STATISTICS 1
/// Min-max bin count
#define MTS_KD_MINMAX_BINS 32
#define MTS_KD_MINMAX_BINS 128
/// OrderedChunkAllocator: don't create chunks smaller than 512KiB
#define MTS_KD_MIN_ALLOC 512*1024
@ -415,9 +415,36 @@ private:
};
/**
* \brief Generic kd-tree for data structure used to accelerate
* ray intersections against large amounts of three-dimensional
* shapes.
* \brief SAH KD-tree acceleration data structure for fast ray-object
* intersection computations.
*
* The code in this class is fully generic and can theoretically
* support any kind of shape. Subclasses need to provide the following
* signatures for a functional implementation:
*
* /// Return the total number of primitives
* inline size_type getPrimitiveCount() const;
*
* /// Return an axis-aligned bounding box of a certain primitive
* inline AABB getAABB(index_type primIdx) const;
*
* /// Return an AABB of a primitive when clipped to another AABB
* inline AABB getClippedAABB(index_type primIdx, const AABB &aabb) const;
*
* This class follows the "Curiously recurring template" design pattern so that
* the above functions can be inlined (no virtual calls will be necessary!).
*
* The kd-tree construction algorithm creates 'perfect split' trees as
* outlined in the paper "On Building fast kd-Trees for Ray Tracing, and on
* doing that in O(N log N)" by Ingo Wald and Vlastimil Havran.
*
* Because the O(N log N) construction algorithm tends to cause many
* incoherent memory accesses, a fast approximate technique (Min-max binning)
* is used near the top of the tree, which significantly reduces cache misses.
* Once the input data has been narrowed down to a reasonable amount, the
* implementation switches over to the O(N log N) builder. When multiple
* processors are available, the build process runs in parallel.
*
*/
template <typename Derived> class GenericKDTree : public Object {
protected:
@ -436,7 +463,7 @@ public:
* \brief Create a new kd-tree instance initialized with
* the default parameters.
*/
GenericKDTree() : m_root(NULL), m_primIndices(NULL) {
GenericKDTree() : m_nodes(NULL), m_primIndices(NULL) {
m_traversalCost = 15;
m_intersectionCost = 20;
m_emptySpaceBonus = 0.9f;
@ -446,22 +473,24 @@ public:
m_exactPrimThreshold = 16384;
m_maxDepth = 1024;
m_retract = true;
m_parallel = false;
m_parallel = true;
}
virtual ~GenericKDTree() {
if (m_primIndices)
delete[] m_primIndices;
if (m_nodes)
delete[] m_nodes;
}
/**
* \brief Build a KD-tree over supplied geometry
*/
void build() {
if (m_root != NULL)
if (m_nodes != NULL)
Log(EError, "The kd-tree has already been built!");
size_type primCount = downCast()->getPrimitiveCount();
size_type primCount = cast()->getPrimitiveCount();
BuildContext ctx(primCount);
/* Establish an ad-hoc depth cutoff value (Formula from PBRT) */
@ -478,7 +507,7 @@ public:
ref<Timer> timer = new Timer();
m_aabb.reset();
for (index_type i=0; i<primCount; ++i) {
m_aabb.expandBy(downCast()->getAABB(i));
m_aabb.expandBy(cast()->getAABB(i));
indices[i] = i;
}
@ -506,7 +535,7 @@ public:
if (m_parallel) {
m_builders.resize(procCount);
for (size_type i=0; i<procCount; ++i) {
m_builders[i] = new SAHTreeBuilder(i+1, primCount, m_interface);
m_builders[i] = new SAHTreeBuilder(i, this);
m_builders[i]->incRef();
m_builders[i]->start();
}
@ -515,11 +544,10 @@ public:
Log(EInfo, "Constructing a SAH kd-tree (%i primitives) ..", primCount);
m_indirectionLock = new Mutex();
m_root = ctx.nodes.allocate(1);
Float finalSAHCost = buildTreeMinMax(ctx, 1, m_root,
KDNode *prelimRoot = ctx.nodes.allocate(1);
Float finalSAHCost = buildTreeMinMax(ctx, 1, prelimRoot,
m_aabb, m_aabb, indices, primCount, true, 0);
ctx.leftAlloc.release(indices);
m_indirectionLock = NULL;
KDAssert(ctx.leftAlloc.getUsed() == 0);
KDAssert(ctx.rightAlloc.getUsed() == 0);
@ -530,6 +558,7 @@ public:
for (size_type i=0; i<m_builders.size(); ++i)
m_builders[i]->join();
}
Log(EInfo, "Finished -- took %i ms.", timer->getMilliseconds());
Log(EDebug, "");
@ -557,22 +586,32 @@ public:
Log(EDebug, "");
timer->reset();
Log(EDebug, "Optimizing data structure layout ..");
std::stack<boost::tuple<const KDNode *, AABB> > stack;
stack.push(boost::make_tuple(m_root, m_aabb));
Log(EDebug, "Optimizing memory layout ..");
std::stack<boost::tuple<const KDNode *, KDNode *, BuildContext *, AABB> > stack;
Float expTraversalSteps = 0;
Float expLeavesVisited = 0;
Float expPrimitivesIntersected = 0;
size_type nodePtr = 0, indexPtr = 0;
m_nodes = new KDNode[ctx.innerNodeCount + ctx.leafNodeCount];
m_primIndices = new index_type[ctx.primIndexCount];
stack.push(boost::make_tuple(prelimRoot, &m_nodes[nodePtr++], &ctx, m_aabb));
while (!stack.empty()) {
const KDNode *node = boost::get<0>(stack.top());
AABB aabb = boost::get<1>(stack.top());
KDNode *target = boost::get<1>(stack.top());
BuildContext *context = boost::get<2>(stack.top());
AABB aabb = boost::get<3>(stack.top());
stack.pop();
if (node->isLeaf()) {
size_t primCount = node->getPrimEnd() - node->getPrimStart();
expLeavesVisited += aabb.getSurfaceArea();
expPrimitivesIntersected += aabb.getSurfaceArea() * primCount;
target->initLeafNode(indexPtr, primCount);
indexPtr += primCount;
} else {
expTraversalSteps += aabb.getSurfaceArea();
const KDNode *left;
@ -580,19 +619,29 @@ public:
left = node->getLeft();
else
left = m_indirections[node->getIndirectionIndex()];
KDNode *children = &m_nodes[nodePtr];
nodePtr += 2;
uint8_t axis = node->getAxis();
float split = node->getSplit();
bool result = target->initInnerNode(axis, split, children - target);
if (!result)
Log(EError, "Cannot represent relative pointer -- too many primitives?");
Float tmp = aabb.min[axis];
aabb.min[axis] = node->getSplit();
stack.push(boost::make_tuple(left+1, aabb));
aabb.min[axis] = split;
stack.push(boost::make_tuple(left+1, children+1, context, aabb));
aabb.min[axis] = tmp;
aabb.max[axis] = node->getSplit();
stack.push(boost::make_tuple(left, aabb));
aabb.max[axis] = split;
stack.push(boost::make_tuple(left, children, context, aabb));
}
}
KDAssert(nodePtr == ctx.innerNodeCount + ctx.leafNodeCount);
KDAssert(indexPtr == ctx.primIndexCount);
Log(EDebug, "Finished -- took %i ms.", timer->getMilliseconds());
/* Free some more memory */
ctx.nodes.clear();
ctx.indices.clear();
for (size_type i=0; i<m_builders.size(); ++i) {
@ -600,6 +649,8 @@ public:
subCtx.nodes.clear();
subCtx.indices.clear();
}
m_indirectionLock = NULL;
std::vector<KDNode *>().swap(m_indirections);
if (m_builders.size() > 0) {
for (size_type i=0; i<m_builders.size(); ++i)
@ -615,15 +666,19 @@ public:
expPrimitivesIntersected /= rootSA;
Log(EDebug, "Detailed kd-tree statistics:");
Log(EDebug, " Final SAH cost : %.2f", finalSAHCost);
Log(EDebug, " Inner nodes : %i", ctx.innerNodeCount);
Log(EDebug, " Leaf nodes : %i", ctx.leafNodeCount);
Log(EDebug, " Nonempty leaf nodes : %i", ctx.nonemptyLeafNodeCount);
Log(EDebug, " Node storage cost : %.2f KiB",
(nodePtr * sizeof(KDNode)) / 1024.0f);
Log(EDebug, " Index storage cost : %.2f KiB",
(indexPtr * sizeof(index_type)) / 1024.0f);
Log(EDebug, " Retracted splits : %i", ctx.retractedSplits);
Log(EDebug, " Pruned primitives : %i", ctx.pruned);
Log(EDebug, " Exp. traversals/ray : %.2f", expTraversalSteps);
Log(EDebug, " Exp. leaf visits/ray : %.2f", expLeavesVisited);
Log(EDebug, " Exp. prim. visits/ray : %.2f", expPrimitivesIntersected);
Log(EDebug, " Final SAH cost : %.2f", finalSAHCost);
Log(EDebug, "");
@ -748,15 +803,17 @@ protected:
size_type leafNodeCount;
size_type nonemptyLeafNodeCount;
size_type innerNodeCount;
size_type primIndexCount;
size_type retractedSplits;
size_type pruned;
BuildContext(size_type primCount) : classStorage(primCount) {
classStorage.setPrimitiveCount(primCount);
retractedSplits = 0;
leafNodeCount = 0;
nonemptyLeafNodeCount = 0;
innerNodeCount = 0;
primIndexCount = 0;
retractedSplits = 0;
pruned = 0;
}
@ -775,6 +832,7 @@ protected:
leafNodeCount += ctx.leafNodeCount;
nonemptyLeafNodeCount += ctx.nonemptyLeafNodeCount;
innerNodeCount += ctx.innerNodeCount;
primIndexCount += ctx.primIndexCount;
retractedSplits += ctx.retractedSplits;
pruned += ctx.pruned;
}
@ -787,7 +845,7 @@ protected:
struct BuildInterface {
/* Communcation */
ref<Mutex> mutex;
ref<ConditionVariable> cond;
ref<ConditionVariable> cond, condJobTaken;
bool done;
/* Job description for building a subtree */
@ -801,6 +859,8 @@ protected:
inline BuildInterface() {
mutex = new Mutex();
cond = new ConditionVariable(mutex);
condJobTaken = new ConditionVariable(mutex);
node = NULL;
done = false;
}
};
@ -937,8 +997,12 @@ protected:
*/
class SAHTreeBuilder : public Thread {
public:
SAHTreeBuilder(size_type idx, size_type primCount, BuildInterface &interface)
: Thread(formatString("bld%i", idx)), m_context(primCount), m_interface(interface) {
SAHTreeBuilder(size_type idx, GenericKDTree *parent)
: Thread(formatString("bld%i", idx+1)),
m_parent(parent),
m_context(parent->cast()->getPrimitiveCount()),
m_interface(parent->m_interface) {
setCritical(true);
}
~SAHTreeBuilder() {
@ -947,11 +1011,33 @@ protected:
}
void run() {
OrderedChunkAllocator &leftAlloc = m_context.leftAlloc;
while (true) {
m_interface.mutex->lock();
while (!m_interface.done) {
while (!m_interface.done && !m_interface.node)
m_interface.cond->wait();
}
if (m_interface.done) {
m_interface.mutex->unlock();
break;
}
int depth = m_interface.depth;
KDNode *node = m_interface.node;
AABB nodeAABB = m_interface.nodeAABB;
size_t eventCount = m_interface.eventEnd - m_interface.eventStart;
size_type primCount = m_interface.primCount;
int badRefines = m_interface.badRefines;
EdgeEvent *eventStart = leftAlloc.allocate<EdgeEvent>(eventCount),
*eventEnd = eventStart + eventCount;
memcpy(eventStart, m_interface.eventStart, eventCount * sizeof(EdgeEvent));
m_interface.node = NULL;
m_interface.condJobTaken->signal();
m_interface.mutex->unlock();
std::sort(eventStart, eventEnd, EdgeEventOrdering());
m_parent->buildTreeSAH(m_context, depth, node,
nodeAABB, eventStart, eventEnd, primCount, true, badRefines);
leftAlloc.release(eventStart);
}
}
inline BuildContext &getContext() {
@ -959,17 +1045,18 @@ protected:
}
private:
GenericKDTree *m_parent;
BuildContext m_context;
BuildInterface &m_interface;
};
/// Cast to the derived class
inline Derived *downCast() {
inline Derived *cast() {
return static_cast<Derived *>(this);
}
/// Cast to the derived class (const version)
inline const Derived *downCast() const {
inline const Derived *cast() const {
return static_cast<Derived *>(this);
}
@ -989,11 +1076,11 @@ protected:
index_type index = prims[i];
AABB aabb;
if (m_clip) {
aabb = downCast()->getClippedAABB(index, nodeAABB);
aabb = cast()->getClippedAABB(index, nodeAABB);
if (!aabb.isValid() || aabb.getSurfaceArea() == 0)
continue;
} else {
aabb = downCast()->getAABB(index);
aabb = cast()->getAABB(index);
}
for (int axis=0; axis<3; ++axis) {
@ -1045,6 +1132,7 @@ protected:
}
}
KDAssert(seenPrims == primCount);
ctx.primIndexCount += primCount;
}
ctx.leafNodeCount++;
}
@ -1068,6 +1156,7 @@ protected:
ctx.nonemptyLeafNodeCount++;
for (size_type i=0; i<primCount; ++i)
ctx.indices.push_back(indices[i]);
ctx.primIndexCount += primCount;
}
ctx.leafNodeCount++;
}
@ -1114,6 +1203,7 @@ protected:
}
ctx.indices.resize(start + primCount);
ctx.primIndexCount = ctx.primIndexCount - actualCount + primCount;
alloc.release(tempStart);
}
@ -1164,13 +1254,32 @@ protected:
OrderedChunkAllocator &alloc = isLeftChild ? ctx.leftAlloc : ctx.rightAlloc;
boost::tuple<EdgeEvent *, EdgeEvent *, size_type> events
= createEventList(alloc, nodeAABB, indices, primCount);
Float sahCost;
if (m_parallel) {
m_interface.mutex->lock();
m_interface.depth = depth;
m_interface.node = node;
m_interface.nodeAABB = nodeAABB;
m_interface.eventStart = boost::get<0>(events);
m_interface.eventEnd = boost::get<1>(events);
m_interface.primCount = boost::get<2>(events);
badRefines = badRefines;
m_interface.cond->signal();
/* Wait for a worker thread to take this job */
while (m_interface.node)
m_interface.condJobTaken->wait();
m_interface.mutex->unlock();
// Never tear down this subtree (return a SAH cost of -infinity)
sahCost = -std::numeric_limits<Float>::infinity();
} else {
std::sort(boost::get<0>(events), boost::get<1>(events), EdgeEventOrdering());
Float sahCost = buildTreeSAH(ctx, depth, node, nodeAABB,
sahCost = buildTreeSAH(ctx, depth, node, nodeAABB,
boost::get<0>(events), boost::get<1>(events), boost::get<2>(events),
isLeftChild, badRefines);
}
alloc.release(boost::get<0>(events));
return sahCost;
}
@ -1180,7 +1289,7 @@ protected:
/* ==================================================================== */
MinMaxBins<MTS_KD_MINMAX_BINS> bins(tightAABB);
bins.bin(downCast(), indices, primCount);
bins.bin(cast(), indices, primCount);
/* ==================================================================== */
/* Split candidate search */
@ -1204,7 +1313,7 @@ protected:
/* ==================================================================== */
boost::tuple<AABB, index_type *, AABB, index_type *> partition =
bins.partition(ctx, downCast(), indices, bestSplit, isLeftChild,
bins.partition(ctx, cast(), indices, bestSplit, isLeftChild,
m_traversalCost, m_intersectionCost);
/* ==================================================================== */
@ -1547,8 +1656,8 @@ protected:
generate new events for each side */
const index_type index = event->index;
AABB clippedLeft = downCast()->getClippedAABB(index, leftNodeAABB);
AABB clippedRight = downCast()->getClippedAABB(index, rightNodeAABB);
AABB clippedLeft = cast()->getClippedAABB(index, leftNodeAABB);
AABB clippedRight = cast()->getClippedAABB(index, rightNodeAABB);
KDAssert(leftNodeAABB.contains(clippedLeft));
KDAssert(rightNodeAABB.contains(clippedRight));
@ -1714,7 +1823,7 @@ protected:
* Ray Tracing of Dynamic Scenes"
* by M. Shevtsov, A. Soupikov and A. Kapustin
*
* @tparam BinCount Number of bins to be allocated
* \tparam BinCount Number of bins to be allocated
*/
template <int BinCount> struct MinMaxBins {
MinMaxBins(const AABB &aabb) : m_aabb(aabb) {
@ -1973,7 +2082,7 @@ protected:
};
private:
KDNode *m_root;
KDNode *m_nodes;
index_type *m_primIndices;
Float m_traversalCost;
Float m_intersectionCost;

2
src/tests/test_kd.cpp
View File

@ -112,7 +112,7 @@ public:
void test02_buildSimple() {
Properties bunnyProps("ply");
bunnyProps.setString("filename", "tools/tests/bunny.ply");
bunnyProps.setString("filename", "tools/tests/happy.ply");
ref<TriMesh> mesh = static_cast<TriMesh *> (PluginManager::getInstance()->
createObject(TriMesh::m_theClass, bunnyProps));