Commit 3040910c authored by Xuan Thang Nguyen's avatar Xuan Thang Nguyen
Browse files

add comments and reorder pivot calc place

parent abb378c4

src/quicksort/quicksort_1Block.cuh

+21 −16
Original line number Diff line number Diff line
@@ -78,8 +78,8 @@ __device__ void singleBlockQuickSort(ArrayView<int, TNL::Devices::Cuda> arr, 
{

    static __shared__ int stackTop;

    static __shared__ int stackArrBegin[stackSize], stackArrEnd[stackSize], stackDepth[stackSize];

    static __shared__ int begin, end, depth,pivotBegin, pivotEnd;

    static __shared__ int pivot;

    static __shared__ int begin, end, depth;

    static __shared__ int pivot, pivotBegin, pivotEnd;



    if (threadIdx.x == 0)

    {
@@ -93,53 +93,58 @@ __device__ void singleBlockQuickSort(ArrayView<int, TNL::Devices::Cuda> arr, 


    while(stackTop > 0)

    {

        //pick up partition to break up

        if (threadIdx.x == 0)

        {

            begin = stackArrBegin[stackTop-1];

            end = stackArrEnd[stackTop-1];

            depth = stackDepth[stackTop-1];

            stackTop--;

            pivot = pickPivot((depth&1) == 0? 

                                    arr.getView(begin, end) :

                                    aux.getView(begin, end),

                                Cmp

                            );

        }

        __syncthreads();



        int size = end - begin;

        auto src = (depth&1) == 0 ? arr.getView(begin, end) : aux.getView(begin, end);

        auto dst = (depth&1) == 0 ? aux.getView(begin, end) : arr.getView(begin, end);

        auto &src = (depth&1) == 0 ? arr : aux;



        //small enough for for bitonic

        if(size <= blockDim.x*2)

        {

            externSort<Function, 2048>(src, arr.getView(begin, end), Cmp);

            externSort<Function, 2048>(src.getView(begin, end), arr.getView(begin, end), Cmp);

            __syncthreads();

            continue;

        }

        //------------------------------------------------------



        //actually do partitioning from here on out

        if(threadIdx.x == 0)

            pivot = pickPivot(src.getView(begin, end),Cmp);

        __syncthreads();



        int smaller = 0, bigger = 0;

        countElem(src, smaller, bigger, pivot);

        countElem(src.getView(begin, end), smaller, bigger, pivot);



        //synchronization is in this function already

        int smallerOffset = blockInclusivePrefixSum(smaller);

        int biggerOffset = blockInclusivePrefixSum(bigger);



        if (threadIdx.x == blockDim.x - 1)

        if (threadIdx.x == blockDim.x - 1) //has sum of all smaller and greater elements than pivot in src

        {

            pivotBegin = smallerOffset;

            pivotBegin = 0 + smallerOffset;

            pivotEnd = size - biggerOffset;

        }

        __syncthreads();



        int destSmaller = 0 + smallerOffset - smaller;

        int destSmaller = 0 + (smallerOffset - smaller);

        int destBigger = pivotEnd  + (biggerOffset - bigger);

        auto &dst = (depth&1) == 0 ? aux : arr;



        copyData(src, dst, destSmaller, destBigger, pivot);

        copyData(src.getView(begin, end), dst.getView(begin, end), destSmaller, destBigger, pivot);

        __syncthreads();



        for (int i = pivotBegin + threadIdx.x; i < pivotEnd; i += blockDim.x)

            arr[begin + i] = pivot;



        //creates new tasks

        if(threadIdx.x == 0)

        {

            stackPush<stackSize>(stackArrBegin, stackArrEnd, stackDepth, stackTop,
@@ -147,6 +152,6 @@ __device__ void singleBlockQuickSort(ArrayView<int, TNL::Devices::Cuda> arr, 
                    begin +pivotEnd, end,

                    depth);

        }

        __syncthreads();

        __syncthreads(); //sync to update stackTop

    } //ends while loop

}
 
 No newline at end of file