global memory bitonic sort

Author: AndrewBoessen

makefile Makefilemakefile renamed to Makefile

@@ -6,14 +6,17 @@ CUDA_PATH = /opt/cuda
 INCLUDES = -I$(CUDA_PATH)/include
 LDFLAGS = -L$(CUDA_PATH)/lib64 -lcudart
 
-all: cpu_bitonic_sort warp_bitonic_sort smem_bitonic_sort
+all: cpu_bitonic_sort warp_bitonic_sort smem_bitonic_sort global_bitonic_sort
 
 warp_bitonic_sort: main.o warp_bitonic_sort.o
 	$(CXX) $^ -o $@ $(LDFLAGS)
 
 smem_bitonic_sort: main.o smem_bitonic_sort.o
 	$(CXX) $^ -o $@ $(LDFLAGS)
 
+global_bitonic_sort: main.o global_bitonic_sort.o
+	$(CXX) $^ -o $@ $(LDFLAGS)
+
 cpu_bitonic_sort: cpu_bitonic_sort.cpp
 	$(CXX) $^ -o $@
 
@@ -26,5 +29,8 @@ warp_bitonic_sort.o: warp_bitonic_sort.cu bitonic_sort.cuh
 smem_bitonic_sort.o: smem_bitonic_sort.cu bitonic_sort.cuh
 	$(NVCC) $(NVCCFLAGS) -c $< -o $@
 
+global_bitonic_sort.o: global_bitonic_sort.cu bitonic_sort.cuh
+	$(NVCC) $(NVCCFLAGS) -c $< -o $@
+
 clean:
-	rm -f *.o warp_bitonic_sort smem_bitonic_sort cpu_bitonic_sort
+	rm -f *.o warp_bitonic_sort smem_bitonic_sort cpu_bitonic_sort global_bitonic_sort

global_bitonic_sort.cu

@@ -0,0 +1,84 @@
+/**
+ * Global Memory Bitoic Sort
+ *
+ * This uses gpu global memory to sort arrays to sort long arrays of ints
+ *
+ * Author: Andrew Boessen
+ */
+
+#include "bitonic_sort.cuh"
+
+/**
+ * Swap
+ *
+ * This is used for swapping elements in bitonic sorting
+ *
+ * @param x caller line id's value
+ * @param mask source lane id = caller line id ^ mask
+ * @param dir direction to swap
+ * @param arr global memory array
+ *
+ */
+__device__ void swap(int x, int mask, int dir, int *arr) {
+  // get correspondin element to x in butterfly diagram
+  int y = x ^ mask;
+  // lower ids thread perform swap
+  if (y > x) {
+    if (dir) {
+      // sort ascending
+      if (arr[x] < arr[y]) {
+        int temp = arr[x];
+        arr[x] = arr[y];
+        arr[y] = temp;
+      }
+    } else {
+      // sort descending
+      if (arr[x] > arr[y]) {
+        int temp = arr[x];
+        arr[x] = arr[y];
+        arr[y] = temp;
+      }
+    }
+  }
+}
+
+/**
+ * Global Memory Bitonic Sort
+ *
+ * The function uses the butterfly network pattern of bitonic sort, leveraging
+ * CUDA's warp-level primitives for efficient sorting within a warp (32
+ * threads). The swaps are tiled into warps of 32 threads. This is able to do
+ * swaps without allocating extra memory for temporary variable.
+ *
+ * @param arr Pointer to the array of integers to be sorted
+ * @param size Total number of elements in the array
+ *
+ * @note This function assumes that the number of threads per block is at least
+ * equal to the warp size. Elements beyond the array size are padded with
+ * INT_MAX.
+ *
+ * @see swap() for the element comparison and swapping logic
+ */
+__global__ void globalBitonicSort(int *arr, int size) {
+  // local thread id in block
+  int thread_id = threadIdx.x + blockIdx.x * blockDim.x;
+
+  // make bitonic sequence and sort
+  for (int i = 0; (1 << i) <= blockDim.x; i++) {
+    for (int j = 1; j <= i; j++) {
+      // distance between caller and source lanes
+      int mask = 1 << (i - j);
+
+      // perform compare and swap
+      int dir = thread_id & (1 << i);
+      swap(thread_id, mask, dir, arr);
+      __syncthreads();
+    }
+  }
+}
+
+void launchBitonicSort(int *arr, int size) {
+  const int BLOCK_SIZE = 512;
+  const int NUM_BLOCKS = (size + BLOCK_SIZE - 1) / BLOCK_SIZE;
+  globalBitonicSort<<<NUM_BLOCKS, BLOCK_SIZE>>>(arr, size);
+}