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[UR][L0] Refine default device logic in urDeviceGet #20036

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merged 1 commit into from
Oct 9, 2025
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[UR][L0] Refine default device logic in urDeviceGet #20036

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40 changes: 35 additions & 5 deletions unified-runtime/source/adapters/level_zero/device.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -104,6 +104,13 @@ ur_result_t urDeviceGet(
// nullptr in this mode.
// - If COMBINED, L0 returns tiles as devices, and zeDeviceGetRootdevice
// returns the card containing a given tile.

// Track best discrete and integrated GPU candidates (device, max compute
// units)
std::pair<ur_device_handle_t, uint32_t> GPUDeviceDiscrete = {nullptr, 0};
std::pair<ur_device_handle_t, uint32_t> GPUDeviceIntegrated = {nullptr, 0};
bool DeviceDefaultGPU = false;

bool isCombinedMode =
std::any_of(Platform->URDevicesCache.begin(),
Platform->URDevicesCache.end(), [](const auto &D) {
Expand Down Expand Up @@ -133,8 +140,11 @@ ur_result_t urDeviceGet(
Matched = true;
break;
case UR_DEVICE_TYPE_GPU:
Matched = (D->ZeDeviceProperties->type == ZE_DEVICE_TYPE_GPU);
break;
case UR_DEVICE_TYPE_DEFAULT:
Matched = (D->ZeDeviceProperties->type == ZE_DEVICE_TYPE_GPU);
DeviceDefaultGPU = true;
break;
case UR_DEVICE_TYPE_CPU:
Matched = (D->ZeDeviceProperties->type == ZE_DEVICE_TYPE_CPU);
Expand All @@ -156,15 +166,35 @@ ur_result_t urDeviceGet(
isCombinedMode && (D->ZeDeviceProperties->flags &
ZE_DEVICE_PROPERTY_FLAG_SUBDEVICE) == 0;
if (!isComposite) {
MatchedDevices.push_back(D.get());
// For UR_DEVICE_TYPE_DEFAULT only a single device should be returned,
// so exit the loop after first proper match.
if (DeviceType == UR_DEVICE_TYPE_DEFAULT)
break;
// In case of DeviceType is DEFAULT, pick only the most powerful GPU
// device.
if (DeviceDefaultGPU) {
uint32_t maxComputeUnits = 0;
ur_result_t UrRet = ur::level_zero::urDeviceGetInfo(
D.get(), UR_DEVICE_INFO_MAX_COMPUTE_UNITS,
sizeof(maxComputeUnits), &maxComputeUnits, nullptr);
maxComputeUnits = (UrRet == UR_RESULT_SUCCESS) ? maxComputeUnits : 0;
auto &BestGpu =
D->isIntegrated() ? GPUDeviceIntegrated : GPUDeviceDiscrete;
if (!BestGpu.first || maxComputeUnits > BestGpu.second)
BestGpu = std::make_pair(D.get(), maxComputeUnits);
} else {
MatchedDevices.push_back(D.get());
}
}
}
}

// Handle GPU/DEFAULT device selection outside the loop
if (DeviceDefaultGPU) {
// Prefer discrete GPU over integrated GPU
if (GPUDeviceDiscrete.first) {
MatchedDevices = {GPUDeviceDiscrete.first};
} else if (GPUDeviceIntegrated.first) {
MatchedDevices = {GPUDeviceIntegrated.first};
}
}

uint32_t ZeDeviceCount = MatchedDevices.size();

auto N = (std::min)(ZeDeviceCount, NumEntries);
Expand Down