performance: cache devices to expose via zeDeviceGet API call

vector with all device handles is initialized only once, during driver init

Signed-off-by: Mateusz Jablonski <mateusz.jablonski@intel.com>

level_zero/core/source/driver/driver_handle_imp.cpp

@@ -323,15 +323,12 @@ ze_result_t DriverHandleImp::initialize(std::vector<std::unique_ptr<NEO::Device>
         }
     }
 
-    uint32_t numDevicesToExpose = 0u;
+    setupDevicesToExpose();
-    this->getDevice(&numDevicesToExpose, nullptr);
-    this->devicesToExpose.resize(numDevicesToExpose);
-    this->getDevice(&numDevicesToExpose, this->devicesToExpose.data());
     uint32_t deviceIdentifier = 0u;
     for (auto &deviceToExpose : this->devicesToExpose) {
         Device::fromHandle(deviceToExpose)->setIdentifier(deviceIdentifier++);
     }
-    createContext(&DefaultDescriptors::contextDesc, numDevicesToExpose, this->devicesToExpose.data(), &defaultContext);
+    createContext(&DefaultDescriptors::contextDesc, static_cast<uint32_t>(this->devicesToExpose.size()), this->devicesToExpose.data(), &defaultContext);
 
     return ZE_RESULT_SUCCESS;
 }
@@ -396,7 +393,7 @@ void DriverHandleImp::initDeviceUsmAllocPool(NEO::Device &device) {
     }
 }
 
-ze_result_t DriverHandleImp::getDevice(uint32_t *pCount, ze_device_handle_t *phDevices) {
+void DriverHandleImp::setupDevicesToExpose() {
 
     // If the user has requested FLAT or COMBINED device hierarchy model, then report all the sub devices as devices.
     bool exposeSubDevices = (this->devices.size() && this->devices[0]->getNEODevice()->getExecutionEnvironment()->getDeviceHierarchyMode() != NEO::DeviceHierarchyMode::composite);
@@ -416,6 +413,30 @@ ze_result_t DriverHandleImp::getDevice(uint32_t *pCount, ze_device_handle_t *phD
     } else {
         numDevices = this->numDevices;
     }
+    this->devicesToExpose.clear();
+    this->devicesToExpose.reserve(numDevices);
+
+    for (auto device : devices) {
+
+        auto deviceImpl = static_cast<DeviceImp *>(device);
+        if (deviceImpl->numSubDevices > 0 && exposeSubDevices) {
+
+            if (device->getNEODevice()->getExecutionEnvironment()->rootDeviceEnvironments[device->getRootDeviceIndex()]->isExposeSingleDeviceMode()) {
+                this->devicesToExpose.push_back(device);
+                continue;
+            }
+
+            for (auto subdevice : deviceImpl->subDevices) {
+                this->devicesToExpose.push_back(subdevice);
+            }
+        } else {
+            this->devicesToExpose.push_back(device);
+        }
+    }
+}
+
+ze_result_t DriverHandleImp::getDevice(uint32_t *pCount, ze_device_handle_t *phDevices) {
+    uint32_t numDevices = static_cast<uint32_t>(this->devicesToExpose.size());
     if (*pCount == 0) {
         *pCount = numDevices;
         return ZE_RESULT_SUCCESS;
@@ -425,35 +446,11 @@ ze_result_t DriverHandleImp::getDevice(uint32_t *pCount, ze_device_handle_t *phD
         return ZE_RESULT_ERROR_INVALID_NULL_HANDLE;
     }
 
-    uint32_t i = 0;
+    auto numDevicesToReturn = std::min(numDevices, *pCount);
-    for (auto device : devices) {
 
-        auto deviceImpl = static_cast<DeviceImp *>(device);
+    memcpy_s(phDevices, numDevicesToReturn * sizeof(ze_device_handle_t), this->devicesToExpose.data(), numDevicesToReturn * sizeof(ze_device_handle_t));
-        if (deviceImpl->numSubDevices > 0 && exposeSubDevices) {
 
-            if (device->getNEODevice()->getExecutionEnvironment()->rootDeviceEnvironments[device->getRootDeviceIndex()]->isExposeSingleDeviceMode()) {
+    *pCount = numDevicesToReturn;
-                phDevices[i++] = device;
-                if (i == *pCount) {
-                    return ZE_RESULT_SUCCESS;
-                }
-                continue;
-            }
-
-            for (auto subdevice : deviceImpl->subDevices) {
-                phDevices[i++] = subdevice;
-                if (i == *pCount) {
-                    return ZE_RESULT_SUCCESS;
-                }
-            }
-        } else {
-            phDevices[i++] = device;
-            if (i == *pCount) {
-                return ZE_RESULT_SUCCESS;
-            }
-        }
-    }
-
-    *pCount = numDevices;
     return ZE_RESULT_SUCCESS;
 }
 

level_zero/core/source/driver/driver_handle_imp.h

@@ -182,6 +182,7 @@ struct DriverHandleImp : public DriverHandle {
     ze_context_handle_t getDefaultContext() const override {
         return defaultContext;
     }
+    void setupDevicesToExpose();
 
   protected:
     NEO::GraphicsAllocation *getPeerAllocation(Device *device,

level_zero/core/test/unit_tests/sources/driver/test_driver.cpp

@@ -1005,6 +1005,7 @@ TEST_F(DriverHandleTest, givenInitializedDriverWithTwoDevicesWhenGetDeviceIsCall
     auto newNeoDevice = L0::Device::create(driverHandleImp, std::move(testNeoDevice), false, &result);
     driverHandleImp->devices.push_back(newNeoDevice);
     driverHandleImp->numDevices++;
+    driverHandleImp->setupDevicesToExpose();
 
     uint32_t count = 0U;
     result = driverHandle->getDevice(&count, nullptr);

level_zero/core/test/unit_tests/sources/event/test_event.cpp

@@ -3126,6 +3126,7 @@ TEST_F(EventPoolCreateMultiDeviceFlatHierarchy, givenFlatHierarchyWhenCallZeGetD
     }
 
     static_cast<DeviceImp *>(driverHandle->devices[1])->numSubDevices = 0;
+    driverHandle->setupDevicesToExpose();
     uint32_t deviceCount2 = 0;
     result = zeDeviceGet(driverHandle.get(), &deviceCount2, nullptr);
     EXPECT_EQ(ZE_RESULT_SUCCESS, result);