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Diffstat (limited to 'tools/cuda-ab/ip_probe2.cu')
| -rw-r--r-- | tools/cuda-ab/ip_probe2.cu | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/tools/cuda-ab/ip_probe2.cu b/tools/cuda-ab/ip_probe2.cu new file mode 100644 index 0000000..a5fa2ec --- /dev/null +++ b/tools/cuda-ab/ip_probe2.cu @@ -0,0 +1,201 @@ +// SPDX-License-Identifier: BSD-3-Clause +/* + * ip_probe2.cu - why do in-place c stores vanish while prog stores land? + * + * After a vadd that fills c, three variants run on the SAME c: + * 1. scale_if : if (i<n) c[i] *= s; (control, like ip_probe) + * 2. scale_u : c[i] *= s; (unconditional, grid exact) + * 3. fill_c : c[i] = 7.0f; (store only, no load) + * 4. add_c : c[i] = c[i] + 1.0f; (load + store) + * Each stage reads c back and compares against the expected value at that + * stage. A separate prog buffer marks CTA execution. + * + * Build: nvcc -O2 --cudart=static -o ip_probe2 ip_probe2.cu + */ + +#include <cstdio> +#include <cstdlib> +#include <cstring> +#include <cuda_runtime.h> + +#define CHECK(x) \ + do { \ + cudaError_t e_ = (x); \ + if (e_ != cudaSuccess) { \ + printf("CUDA_ERROR %s at line %d\n", \ + cudaGetErrorString(e_), __LINE__); \ + printf("STATUS FAIL\n"); \ + return 1; \ + } \ + } while (0) + +__global__ void vadd(const float *a, const float *b, float *c, int n) +{ + int i = blockIdx.x * blockDim.x + threadIdx.x; + + if (i < n) + c[i] = a[i] + b[i]; +} + +__global__ void scale_if(float *c, float s, int n, unsigned *prog) +{ + int i = blockIdx.x * blockDim.x + threadIdx.x; + + if (i < n) + c[i] = c[i] * s; + if (threadIdx.x == 0) + prog[blockIdx.x] = 0xCAFEBABEu; +} + +__global__ void scale_u(float *c, float s, unsigned *prog) +{ + int i = blockIdx.x * blockDim.x + threadIdx.x; + + c[i] = c[i] * s; + if (threadIdx.x == 0) + prog[blockIdx.x] = 0xDEADBEEFu; +} + +__global__ void fill_c(float *c, unsigned *prog) +{ + int i = blockIdx.x * blockDim.x + threadIdx.x; + + c[i] = 7.0f; + if (threadIdx.x == 0) + prog[blockIdx.x] = 0xFEEDFACu; +} + +__global__ void add_c(float *c, unsigned *prog) +{ + int i = blockIdx.x * blockDim.x + threadIdx.x; + + c[i] = c[i] + 1.0f; + if (threadIdx.x == 0) + prog[blockIdx.x] = 0x0DDF00Du; +} + +int main(int argc, char **argv) +{ + cudaDeviceProp prop; + const int n = 1 << 15; + const int grid = (n + 255) / 256; + size_t bytes = (size_t)n * sizeof(float); + float k = argc > 1 ? atof(argv[1]) : 0.0f; + float *ha, *hb, *hc; + float *da, *db, *dc; + unsigned *d_prog, h_prog[128]; + int i, stage; + float mult; + + setvbuf(stdout, NULL, _IONBF, 0); + CHECK(cudaGetDeviceProperties(&prop, 0)); + printf("DEVICE %s seed=%g\n", prop.name, (double)k); + + ha = (float *)malloc(bytes); + hb = (float *)malloc(bytes); + hc = (float *)malloc(bytes); + for (i = 0; i < n; i++) { + ha[i] = (float)(i % 1000) * 0.5f + k; + hb[i] = (float)(i % 997) * 0.25f + 2.0f * k; + } + memset(hc, 0xCD, bytes); + + CHECK(cudaMalloc(&da, bytes)); + CHECK(cudaMalloc(&db, bytes)); + CHECK(cudaMalloc(&dc, bytes)); + CHECK(cudaMalloc(&d_prog, 128 * sizeof(unsigned))); + printf("DPTRS da=%p db=%p dc=%p prog=%p\n", (void *)da, (void *)db, + (void *)dc, (void *)d_prog); + + CHECK(cudaMemcpy(da, ha, bytes, cudaMemcpyHostToDevice)); + CHECK(cudaMemcpy(db, hb, bytes, cudaMemcpyHostToDevice)); + + vadd<<<grid, 256>>>(da, db, dc, n); + CHECK(cudaDeviceSynchronize()); + CHECK(cudaMemcpy(hc, dc, bytes, cudaMemcpyDeviceToHost)); + { + int b = 0; + + for (i = 0; i < n; i++) + if (hc[i] != ha[i] + hb[i]) + b++; + printf("VADD readback bad=%d/%d\n", b, n); + } + + mult = 2.0f; + for (stage = 0; stage < 4; stage++) { + unsigned mark = 0; + + CHECK(cudaMemset(d_prog, 0xEE, 128 * sizeof(unsigned))); + switch (stage) { + case 0: + scale_if<<<grid, 256>>>(dc, 2.0f, n, d_prog); + mult = 2.0f; + mark = 0xCAFEBABEu; + break; + case 1: + scale_u<<<grid, 256>>>(dc, 2.0f, d_prog); + mult = 4.0f; + mark = 0xDEADBEEFu; + break; + case 2: + fill_c<<<grid, 256>>>(dc, d_prog); + mark = 0xFEEDFACu; + break; + default: + add_c<<<grid, 256>>>(dc, d_prog); + mult = -1.0f; + mark = 0x0DDF00Du; + break; + } + CHECK(cudaDeviceSynchronize()); + CHECK(cudaMemcpy(h_prog, d_prog, 128 * sizeof(unsigned), + cudaMemcpyDeviceToHost)); + { + int marked = 0; + + for (i = 0; i < grid; i++) + if (h_prog[i] == mark) + marked++; + printf("S%d CTA-MARK marked=%d/%d\n", stage + 1, + marked, grid); + } + CHECK(cudaMemcpy(hc, dc, bytes, cudaMemcpyDeviceToHost)); + if (stage < 2) { + int b = 0, first = -1; + + for (i = 0; i < n; i++) + if (hc[i] != (ha[i] + hb[i]) * mult) { + b++; + if (first < 0) + first = i; + } + printf("S%d readback bad=%d/%d first=%d\n", + stage + 1, b, n, first); + } else if (stage == 2) { + int b = 0, first = -1; + + for (i = 0; i < n; i++) + if (hc[i] != 7.0f) { + b++; + if (first < 0) + first = i; + } + printf("S3 readback bad=%d/%d first=%d (fill 7.0)\n", + b, n, first); + } else { + int b = 0, first = -1; + + for (i = 0; i < n; i++) + if (hc[i] != 8.0f) { + b++; + if (first < 0) + first = i; + } + printf("S4 readback bad=%d/%d first=%d (add 1.0 to fill)\n", + b, n, first); + } + } + printf("STATUS DONE\n"); + return 0; +} |