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// SPDX-License-Identifier: BSD-3-Clause
/*
* victory_streams_events.cu - 3 streams, overlapped copies, event ordering.
*
* Three non-default streams each copy their own inputs, run a vectorAdd, and
* are then chained with events:
*
* stream 0: vadd c0 = a0 + b0
* stream 1: waits event e0 from stream 0, then c1 += c0
* stream 2: waits event e1 from stream 1, then c2 += c1
*
* Every stream also does its own async D2H copy; the whole chain is timed
* with cudaEventRecord/cudaEventElapsedTime. The host verifies all three
* outputs; inputs are multiples of 0.25 so the arithmetic is exact in float.
*
* Output lines are stable and greppable:
*
* DEVICE <name> cc=<major>.<minor> sm=<count> mem=<bytes>
* STREAMS3 n=<count> bad=<mismatches>
* TIMING ms=<elapsed>
* STATUS OK|FAIL
*
* Build with a static CUDA runtime (--cudart=static) so the guest only needs
* the driver's libcuda.so, not a CUDA toolkit installation:
*
* nvcc -O2 --cudart=static -o victory_streams_events victory_streams_events.cu
*
* Then, from the guest: /tmp/victory_streams_events
*/
#include <cstdio>
#include <cstdlib>
#include <cstdint>
#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)
#define NSTREAMS 3
__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 vadd_into(float *c, const float *s, int n)
{
int i = blockIdx.x * blockDim.x + threadIdx.x;
if (i < n)
c[i] = c[i] + s[i];
}
int main(void)
{
cudaDeviceProp prop;
const int n = 1 << 16; /* 256 KB per stream */
size_t bytes = (size_t)n * sizeof(float);
float *h_a[NSTREAMS], *h_b[NSTREAMS], *h_c[NSTREAMS];
float *d_a[NSTREAMS], *d_b[NSTREAMS], *d_c[NSTREAMS];
cudaStream_t st[NSTREAMS];
cudaEvent_t ev[NSTREAMS], t0, t1;
float ms = 0.0f;
int bad = 0, i, s;
const int grid = (n + 255) / 256;
setvbuf(stdout, NULL, _IONBF, 0);
CHECK(cudaGetDeviceProperties(&prop, 0));
printf("DEVICE %s cc=%d.%d sm=%d mem=%llu\n", prop.name,
prop.major, prop.minor, prop.multiProcessorCount,
(unsigned long long)prop.totalGlobalMem);
for (s = 0; s < NSTREAMS; s++) {
h_a[s] = (float *)malloc(bytes);
h_b[s] = (float *)malloc(bytes);
h_c[s] = (float *)malloc(bytes);
if (!h_a[s] || !h_b[s] || !h_c[s])
return 1;
for (i = 0; i < n; i++) {
h_a[s][i] = (float)((i + s) % 1000) * 0.5f;
h_b[s][i] = (float)((i + 2 * s) % 997) * 0.25f;
}
CHECK(cudaMalloc(&d_a[s], bytes));
CHECK(cudaMalloc(&d_b[s], bytes));
CHECK(cudaMalloc(&d_c[s], bytes));
CHECK(cudaStreamCreate(&st[s]));
CHECK(cudaEventCreate(&ev[s]));
}
CHECK(cudaEventCreate(&t0));
CHECK(cudaEventCreate(&t1));
CHECK(cudaEventRecord(t0));
for (s = 0; s < NSTREAMS; s++) {
CHECK(cudaMemcpyAsync(d_a[s], h_a[s], bytes,
cudaMemcpyHostToDevice, st[s]));
CHECK(cudaMemcpyAsync(d_b[s], h_b[s], bytes,
cudaMemcpyHostToDevice, st[s]));
vadd<<<grid, 256, 0, st[s]>>>(d_a[s], d_b[s], d_c[s], n);
CHECK(cudaGetLastError());
CHECK(cudaEventRecord(ev[s], st[s]));
}
/* Cross-stream chain: 1 waits on 0, 2 waits on 1. */
CHECK(cudaStreamWaitEvent(st[1], ev[0], 0));
vadd_into<<<grid, 256, 0, st[1]>>>(d_c[1], d_c[0], n);
CHECK(cudaGetLastError());
CHECK(cudaEventRecord(ev[1], st[1]));
CHECK(cudaStreamWaitEvent(st[2], ev[1], 0));
vadd_into<<<grid, 256, 0, st[2]>>>(d_c[2], d_c[1], n);
CHECK(cudaGetLastError());
/* Copies back overlap across the three streams. */
for (s = 0; s < NSTREAMS; s++)
CHECK(cudaMemcpyAsync(h_c[s], d_c[s], bytes,
cudaMemcpyDeviceToHost, st[s]));
CHECK(cudaEventRecord(t1, st[2]));
for (s = 0; s < NSTREAMS; s++)
CHECK(cudaStreamSynchronize(st[s]));
CHECK(cudaEventElapsedTime(&ms, t0, t1));
/* c0 = a0+b0; c1 = (a1+b1)+c0; c2 = (a2+b2)+c1 (all exact floats). */
for (i = 0; i < n; i++) {
float c0 = h_a[0][i] + h_b[0][i];
float c1 = h_a[1][i] + h_b[1][i] + c0;
float c2 = h_a[2][i] + h_b[2][i] + c1;
if (h_c[0][i] != c0)
bad++;
if (h_c[1][i] != c1)
bad++;
if (h_c[2][i] != c2)
bad++;
}
printf("STREAMS3 n=%d bad=%d\n", n, bad);
printf("TIMING ms=%.3f\n", ms);
if (bad != 0) {
printf("STATUS FAIL\n");
return 1;
}
printf("STATUS OK\n");
for (s = 0; s < NSTREAMS; s++) {
CHECK(cudaEventDestroy(ev[s]));
CHECK(cudaStreamDestroy(st[s]));
CHECK(cudaFree(d_a[s]));
CHECK(cudaFree(d_b[s]));
CHECK(cudaFree(d_c[s]));
free(h_a[s]);
free(h_b[s]);
free(h_c[s]);
}
CHECK(cudaEventDestroy(t0));
CHECK(cudaEventDestroy(t1));
return 0;
}
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