将uint数组传递给要填充的Dll(Nvidia NVML库)

Question

我正试图将一个uint数组从C#传递到NVML函数nvmlDeviceGetAccountingPids(此处为Doc(中，以下是我迄今为止所拥有的最小工作示例：

{
public const string NVMLDLL = "nvml.dll";
public static class Constants
{
public const int NVML_DEVICE_INFOROM_VERSION_BUFFER_SIZE = 16;
public const int NVML_DEVICE_NAME_BUFFER_SIZE = 64;
public const int NVML_DEVICE_NAME_V2_BUFFER_SIZE = 96;
public const int NVML_DEVICE_PART_NUMBER_BUFFER_SIZE = 80;
public const int NVML_DEVICE_SERIAL_BUFFER_SIZE = 30;
public const int NVML_DEVICE_UUID_BUFFER_SIZE = 80;
public const int NVML_DEVICE_UUID_V2_BUFFER_SIZE = 96;
public const int NVML_DEVICE_VBIOS_VERSION_BUFFER_SIZE = 32;
public const int NVML_SYSTEM_DRIVER_VERSION_BUFFER_SIZE = 80;
public const int NVML_SYSTEM_NVML_VERSION_BUFFER_SIZE = 80;
public const int NVML_INIT_FLAG_NO_ATTACH = 2;
public const int NVML_INIT_FLAG_NO_GPUS = 1;
}
public enum nvmlReturn_t
{
NVML_SUCCESS = 0,                           // The operation was successful. 
NVML_ERROR_UNINITIALIZED = 1,               // NVML was not first initialized with nvmlInit(). 
NVML_ERROR_INVALID_ARGUMENT = 2,            // A supplied argument is invalid. 
NVML_ERROR_NOT_SUPPORTED = 3,               // The requested operation is not available on target device. 
NVML_ERROR_NO_PERMISSION = 4,               // The current user does not have permission for operation. 
NVML_ERROR_ALREADY_INITIALIZED = 5,         // Deprecated: Multiple initializations are now allowed through ref counting. 
NVML_ERROR_NOT_FOUND = 6,                   // A query to find an object was unsuccessful. 
NVML_ERROR_INSUFFICIENT_SIZE = 7,           // An input argument is not large enough. 
NVML_ERROR_INSUFFICIENT_POWER = 8,          // A device's external power cables are not properly attached. 
NVML_ERROR_DRIVER_NOT_LOADED = 9,           // NVIDIA driver is not loaded. 
NVML_ERROR_TIMEOUT = 10,                    // User provided timeout passed. 
NVML_ERROR_IRQ_ISSUE = 11,                  // NVIDIA Kernel detected an interrupt issue with a GPU. 
NVML_ERROR_LIBRARY_NOT_FOUND = 12,          // NVML Shared Library couldn't be found or loaded. 
NVML_ERROR_FUNCTION_NOT_FOUND = 13,         // Local version of NVML doesn't implement this function. 
NVML_ERROR_CORRUPTED_INFOROM = 14,          // infoROM is corrupted 
NVML_ERROR_GPU_IS_LOST = 15,                // The GPU has fallen off the bus or has otherwise become inaccessible. 
NVML_ERROR_RESET_REQUIRED = 16,             // The GPU requires a reset before it can be used again. 
NVML_ERROR_OPERATING_SYSTEM = 17,           // The GPU control device has been blocked by the operating system/cgroups. 
NVML_ERROR_LIB_RM_VERSION_MISMATCH = 18,    // RM detects a driver/library version mismatch. 
NVML_ERROR_IN_USE = 19,                     // An operation cannot be performed because the GPU is currently in use. 
NVML_ERROR_MEMORY = 20,                     // Insufficient memory. 
NVML_ERROR_NO_DATA = 21,                    // No data. 
NVML_ERROR_VGPU_ECC_NOT_SUPPORTED = 22,     // The requested vgpu operation is not available on target device, becasue ECC is enabled. 
NVML_ERROR_INSUFFICIENT_RESOURCES = 23,     // Ran out of critical resources, other than memory. 
NVML_ERROR_FREQ_NOT_SUPPORTED = 24,         // Ran out of critical resources, other than memory. 
NVML_ERROR_UNKNOWN = 999                    // An internal driver error occurred. 
}
[DllImport(NVMLDLL)]
private static extern nvmlReturn_t nvmlInit_v2();
[DllImport(NVMLDLL)]
private static extern nvmlReturn_t nvmlShutdown();
[DllImport(NVMLDLL)]
private static extern nvmlReturn_t nvmlDeviceGetCount_v2(out uint deviceCount);
[DllImport(NVMLDLL)]
private static extern nvmlReturn_t nvmlDeviceGetHandleByIndex_v2(int index, out IntPtr handle);
[DllImport(NVMLDLL)]
private static extern nvmlReturn_t nvmlDeviceGetName(IntPtr device, [MarshalAs(UnmanagedType.LPStr)] StringBuilder deviceName, uint length);
[DllImport(NVMLDLL)]
private static extern nvmlReturn_t nvmlDeviceGetAccountingPids(IntPtr device, ref uint count, [In, Out] uint[] pids);
static void Main(string[] args)
{
if (nvmlInit_v2() == nvmlReturn_t.NVML_SUCCESS)
{
nvmlDeviceGetCount_v2(out uint deviceCount);
for (int i = 0; i < deviceCount; i++)
{
StringBuilder name = new();
nvmlDeviceGetHandleByIndex_v2(i, out IntPtr _device);
nvmlDeviceGetName(_device, name, Constants.NVML_DEVICE_NAME_V2_BUFFER_SIZE);
// arbitrary number for now
uint count = 5;
uint[] pids = new uint[count];
nvmlDeviceGetAccountingPids(_device, ref count, pids);
foreach(uint ui in pids) Console.WriteLine(ui);
}
nvmlShutdown();
}
}
}

到目前为止，它返回了使用gpu的正确进程数，但PID数组一直返回所有0。我对C#没有特别的经验，所以如果有人能向我展示正确的语法(或者让我知道我是否必须求助于IntPtr(，原始函数有这个签名：

nvmlReturn_t nvmlDeviceGetAccountingPids ( nvmlDevice_t device, unsigned int* count, unsigned int* pids )
Parameters
device
The identifier of the target device 
count
Reference in which to provide the pids array size, and to return the number of elements ready to be queried 
pids
Reference in which to return list of process ids

如果有人知道这个神奇的组合，我一定会很感激，谢谢你抽出时间

Answer 1

有时我认为我只是为了解决问题而键入^_^

static void Main(string[] args)
{
if (nvmlInit_v2() == nvmlReturn_t.NVML_SUCCESS)
{
nvmlDeviceGetCount_v2(out uint deviceCount);
for (int i = 0; i < deviceCount; i++)
{
StringBuilder name = new();
nvmlDeviceGetHandleByIndex_v2(i, out IntPtr _device);
nvmlDeviceGetName(_device, name, Constants.NVML_DEVICE_NAME_V2_BUFFER_SIZE);
// arbitrary number for now
uint count = 0;
nvmlDeviceGetAccountingPids(_device, ref count, null);
uint[] pids = new uint[count];
if (nvmlDeviceGetAccountingPids(_device, ref count, pids) == nvmlReturn_t.NVML_SUCCESS)
{
foreach (uint ui in pids) Console.WriteLine(ui);
}
}
nvmlShutdown();
}

因此，当将计数传递给函数时，它想要与数组大小相同的数字来填充pids列表(我认为这是有道理的(。这是通过仅将计数设置为"0"来检索的；0"；并将一个空数组传递给函数，它将把count设置为数组的大小。创建一个具有该大小的新uint数组，传递array/count和BAM，它会根据需要返回pid。感谢阅读SO！如果有人在语法/实践方面有一些建设性的批评，请发表评论，这样我就可以在编写过程中改进这段代码。祝你度过美好的一天👍