Frank
56fc899763
The RDNA4 offload campaign left three HIP probes and a driver sitting loose in $HOME, where the next agent cannot find them and a stray `rm -rf` ends them. They answer a recurring question on the R9700 box — is decode limited by the link or by the engine's read path — so they move into scripts/probes/ with a driver, tests, and a page. Two things changed in the code, not just the address: - The driver measures only after a guard that runs BEFORE anything is built: gpu_busy_percent over PCIE_PROBE_MAX_BUSY, or any process holding /dev/kfd, is a refusal (exit 3) rather than a measurement. A benchmark taken beside a live endpoint is both disruptive and worthless, and silently unloading a production service is not a tool's decision — --force is the human saying otherwise. The refusal-before-build ordering is pinned by a test, because the sysfs and kfd paths are overridable and a refusal is otherwise untestable off the card box. - hip_smoke.hip and pcie_probe.hip called hipGetDeviceProperties, which SEGFAULTS on this ROCm build even though hipGetDeviceCount works; only pcie_bw.hip avoided it, and that is the one that produced the campaign's numbers. Device identity now comes from the sysfs topology block the driver prints, so all three probes are runnable on the build we ship. Verified here: refusal on a real busy APU (exit 3), missing toolchain (exit 4), missing sources (exit 2). Compile-and-run still needs the box with hipcc. Refs #53
65 lines
2.8 KiB
Plaintext
65 lines
2.8 KiB
Plaintext
// H2D bandwidth at the engine's expert-slab size.
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// Deliberately avoids hipGetDeviceProperties: it segfaults on this ROCm build
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// (hipGetDeviceCount works fine and reports 3 devices).
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#include <cstdio>
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#include <cstring>
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#include <cstdlib>
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#include <hip/hip_runtime.h>
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static double one(size_t bytes, bool pinned, int iters) {
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void *dev = NULL, *host = NULL;
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if (hipMalloc(&dev, bytes) != hipSuccess) return -1;
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if (pinned) { if (hipHostMalloc(&host, bytes, hipHostMallocDefault) != hipSuccess) return -1; }
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else { host = malloc(bytes); }
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memset(host, 0x5a, bytes);
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hipEvent_t a, b; hipEventCreate(&a); hipEventCreate(&b);
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for (int i = 0; i < 3; i++) hipMemcpy(dev, host, bytes, hipMemcpyHostToDevice);
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hipDeviceSynchronize();
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hipEventRecord(a, 0);
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for (int i = 0; i < iters; i++) hipMemcpy(dev, host, bytes, hipMemcpyHostToDevice);
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hipEventRecord(b, 0); hipEventSynchronize(b);
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float ms = 0; hipEventElapsedTime(&ms, a, b);
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double gb = (double)bytes * iters / (ms / 1000.0) / 1e9;
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if (!pinned) free(host); else hipHostFree(host);
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hipFree(dev); hipEventDestroy(a); hipEventDestroy(b);
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return gb;
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}
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int main(int argc, char **argv) {
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setvbuf(stdout, NULL, _IONBF, 0);
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int dev = (argc > 1) ? atoi(argv[1]) : 0;
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if (hipSetDevice(dev) != hipSuccess) { printf("setDevice(%d) failed\n", dev); return 1; }
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printf("device %d selected\n", dev);
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size_t sz[] = {2459136UL, 3UL<<20, 16UL<<20, 64UL<<20, 256UL<<20, 1UL<<30};
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printf(" %10s | %7s | %7s | %7s\n", "MiB", "pinned", "pagin.", "xfer us");
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printf(" %s\n", "-------------------------------------------");
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for (int i = 0; i < 6; i++) {
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size_t b = sz[i];
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int iters = (b >= (1UL<<30)) ? 10 : (b >= (256UL<<20)) ? 20 : 100;
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double p = one(b, true, iters);
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double g = one(b, false, iters);
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// single-transfer latency
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void *dv, *hv;
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if (hipMalloc(&dv, b) == hipSuccess && hipHostMalloc(&hv, b, hipHostMallocDefault) == hipSuccess) {
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memset(hv, 0x5a, b);
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hipEvent_t a, c; hipEventCreate(&a); hipEventCreate(&c);
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hipMemcpy(dv, hv, b, hipMemcpyHostToDevice); hipDeviceSynchronize();
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hipEventRecord(a, 0);
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hipMemcpy(dv, hv, b, hipMemcpyHostToDevice);
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hipEventRecord(c, 0); hipEventSynchronize(c);
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float ms = 0; hipEventElapsedTime(&ms, a, c);
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printf(" %10.3f | %7.2f | %7.2f | %7.1f\n", b/1048576.0, p, g, ms*1000.0);
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hipHostFree(hv); hipFree(dv);
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} else {
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printf(" %10.3f | %7.2f | %7.2f | (alloc failed)\n", b/1048576.0, p, g);
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}
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}
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printf("\n 2.344 MiB is the engine's exact expert slab size.\n");
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printf(" Gen5 x8 ceiling = 31.5 GB/s per direction.\n");
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return 0;
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}
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