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Enable no-src GPU SDMA transfers #295

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Enable no-src GPU SDMA transfers #295

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fdcbf24
Add DMA memset support (no-src EXE_GPU_DMA transfer)
nileshnegi May 10, 2026
a5353d4
Fix DMA memset timing: skip HIP event elapsed time for 0-src transfers
nileshnegi May 10, 2026
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72 changes: 51 additions & 21 deletions src/header/TransferBench.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2313,12 +2313,20 @@ namespace {
}
break;
case EXE_GPU_DMA:
if (t.srcs.size() != 1) {
if (t.srcs.size() > 1) {
errors.push_back({ERR_FATAL,
"Transfer %d: DMA executor must have 0 or 1 sources", i});
hasFatalError = true;
break;
}
#if defined(__NVCC__)
if (t.srcs.empty()) {
errors.push_back({ERR_FATAL,
"Transfer %d: DMA executor must have exactly 1 source", i});
"Transfer %d: DMA memset (0 sources) not supported on NVIDIA hardware", i});
hasFatalError = true;
break;
}
#endif
if (t.dsts.size() < 1) {
errors.push_back({ERR_FATAL,
"Transfer %d: DMA executor must have at least 1 destination", i});
Expand All @@ -2341,6 +2349,12 @@ namespace {
hasFatalError = true;
break;
#else
if (t.srcs.empty()) {
errors.push_back({ERR_FATAL,
"Transfer %d: DMA memset (0 sources) does not support engine selection", i});
hasFatalError = true;
break;
}
useSubIndexCount[t.exeDevice]++;
int numSubIndices = GetNumExecutorSubIndices(t.exeDevice);
if (t.exeSubIndex >= numSubIndices) {
Expand All @@ -2361,7 +2375,6 @@ namespace {
hasFatalError = true;
break;
}

}

int numDsts = (int)t.dsts.size();
Expand Down Expand Up @@ -2400,22 +2413,24 @@ namespace {
#endif
}

if (!IsGpuMemType(t.srcs[0].memType) && !IsGpuMemType(t.dsts[0].memType)) {
errors.push_back({ERR_WARN,
"Transfer %d: No GPU memory for source or destination. Copy might not execute on DMA %d",
i, t.exeDevice.exeIndex});
} else {
// Currently HIP will use src agent if source memory is GPU, otherwise dst agent
if (IsGpuMemType(t.srcs[0].memType)) {
if (t.srcs[0].memIndex != t.exeDevice.exeIndex) {
if (!t.srcs.empty()) {
if (!IsGpuMemType(t.srcs[0].memType) && !IsGpuMemType(t.dsts[0].memType)) {
errors.push_back({ERR_WARN,
"Transfer %d: No GPU memory for source or destination. Copy might not execute on DMA %d",
i, t.exeDevice.exeIndex});
} else {
// Currently HIP will use src agent if source memory is GPU, otherwise dst agent
if (IsGpuMemType(t.srcs[0].memType)) {
if (t.srcs[0].memIndex != t.exeDevice.exeIndex) {
errors.push_back({ERR_WARN,
"Transfer %d: DMA executor may automatically switch to using the source memory device (%d) not (%d)",
i, t.srcs[0].memIndex, t.exeDevice.exeIndex});
}
} else if (t.dsts[0].memIndex != t.exeDevice.exeIndex) {
errors.push_back({ERR_WARN,
"Transfer %d: DMA executor may automatically switch to using the source memory device (%d) not (%d)",
i, t.srcs[0].memIndex, t.exeDevice.exeIndex});
"Transfer %d: DMA executor may automatically switch to using the destination memory device (%d) not (%d)",
i, t.dsts[0].memIndex, t.exeDevice.exeIndex});
}
} else if (t.dsts[0].memIndex != t.exeDevice.exeIndex) {
errors.push_back({ERR_WARN,
"Transfer %d: DMA executor may automatically switch to using the destination memory device (%d) not (%d)",
i, t.dsts[0].memIndex, t.exeDevice.exeIndex});
}
}
break;
Expand Down Expand Up @@ -4263,8 +4278,10 @@ static bool IsConfiguredGid(union ibv_gid const& gid)
rss.dstAgent[dstIdx] = info.agentOwner;
}

ERR_CHECK(hsa_amd_pointer_info(rss.srcMem[0], &info, NULL, NULL, NULL));
rss.srcAgent = info.agentOwner;
if (!rss.srcMem.empty()) {
ERR_CHECK(hsa_amd_pointer_info(rss.srcMem[0], &info, NULL, NULL, NULL));
rss.srcAgent = info.agentOwner;
}

// Create HSA completion signal
ERR_CHECK(hsa_signal_create(1, 0, NULL, &rss.signal));
Expand Down Expand Up @@ -5450,7 +5467,20 @@ static bool IsConfiguredGid(union ibv_gid const& gid)
int numDsts = (int)resources.dstMem.size();
ERR_CHECK(hipSetDevice(exeIndex));
int subIterations = 0;
if (!useSubIndices && !cfg.dma.useHsaCopy) {
if (resources.srcMem.empty()) {
// DMA memset: fill each destination via LINEAR_FILL on SDMA DACC BE.
// count is in uint32_t units; value matches MEMSET_VAL byte pattern (0x4B4B4B4B).
#if !defined(__NVCC__)
uint32_t fillVal;
float const f = MEMSET_VAL;
memcpy(&fillVal, &f, sizeof(fillVal));
size_t const count = resources.numBytes / sizeof(uint32_t);
do {
for (int dstIdx = 0; dstIdx < numDsts; dstIdx++)
ERR_CHECK(hsa_amd_memory_fill(resources.dstMem[dstIdx], fillVal, count));
} while (++subIterations != cfg.general.numSubIterations);
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nileshnegi marked this conversation as resolved.
#endif
} else if (!useSubIndices && !cfg.dma.useHsaCopy) {
if (cfg.dma.useHipEvents)
ERR_CHECK(hipEventRecord(startEvent, stream));

Expand Down Expand Up @@ -5510,7 +5540,7 @@ static bool IsConfiguredGid(union ibv_gid const& gid)

if (iteration >= 0) {
double deltaMsec = cpuDeltaMsec;
if (!useSubIndices && !cfg.dma.useHsaCopy && cfg.dma.useHipEvents) {
if (!resources.srcMem.empty() && !useSubIndices && !cfg.dma.useHsaCopy && cfg.dma.useHipEvents) {
float gpuDeltaMsec;
ERR_CHECK(hipEventElapsedTime(&gpuDeltaMsec, startEvent, stopEvent));
deltaMsec = gpuDeltaMsec / cfg.general.numSubIterations;
Expand Down