[OpenMP] Refined CUDA plugin to put all CUDA operations into class

[tianshilei1992]

Summary

Current implementation mixed everything up so that there is almost no encapsulation. In this patch, all CUDA related operations are put into a new class DeviceRTLTy and only necessary functions are exposed. In addition, all C++ code now conforms with LLVM code standard, keeping those API functions following C style.

[tianshilei1992]

Removed useless headers

[jdoerfert]

First set of comments. We need to split this. I suggested some split points and follow ups.

openmp/libomptarget/include/omptarget.h

21

Split this off, LGTM on this part

openmp/libomptarget/plugins/cuda/src/rtl.cpp

72

I imagine the above is all clang-formated, if so split it off, LGTM on that part. (keep the namsepace as part of the other patch)

90

I don't know where this should go right now but a global list sounds wrong. Follow up.

96

The above is defined in a different header. We should not redefine it here but include the appropriate header. Follow up.

118

1. Can we replace the list with vectors please. We do not add or delete elements once created.
2. Can we make it a template class parametric in the Context type. e.g., struct NVIDIADeviceDataTy : public DeviceDataTy<CUcontext> {}.
3. These should all be unsigned types, right? We also should add explicit documentation for each. I mean NumThreads is some maximum I guess.
4. These types need to go into a common header (see also 2)). Follow up though

173

These three lines can be removed if you move the getenv stuff into init and call resizeStreamPool there.

257

Once we have the common header, the StreamManager interface has to go there as well. We need generic functions for stream create/destory and set context can be done via a DeviceDataTy method.

288–289

Nit: It or better Entry

302

(Off topic: Why do we have a table member that needs to be updated when we use it, that seems wrong.)

347

No braces around return also above.

354

Nice

368

Style: I'd move the getenv calls into the condition if (const ... = getenv)

903

Nit: LLVM style "generally" avoids trailing comments. Maybe inline it: , /* EM_CUDA */ 190

1038

Add comments for the constants or define hem as before. /* ThreadNum */ or something is fine.

1045

I like the validation in the user facing functions. Makes the assertion location better too.

[tianshilei1992]

openmp/libomptarget/plugins/cuda/src/rtl.cpp

72

Okay, got your point.

90

This is what it is originally. Basically I didn't change any logic in this patch. From its usage, looks like it is only for storage. Items will only be emplace_back to it and then get the pointer. That's it.

118

1. Can we replace the list with vectors please. We do not add or delete elements once created.

Yes, we can do that.

2. Can we make it a template class parametric in the Context type. e.g., struct NVIDIADeviceDataTy : public DeviceDataTy<CUcontext> {}.

I don't think so. Now we only know that CUDA has this context thing. We have no idea whether other platforms do. Other things like warp as well.

3. These should all be unsigned types, right? We also should add explicit documentation for each. I mean NumThreads is some maximum I guess.

Yeah, they should be. Will change them correspondingly.

4. These types need to go into a common header (see also 2)). Follow up though.

We should only put the most common part into a common header, but it seems that we only have three known common members: FuncGblEntries, NumTeams, and NumThreads.

173

Correct. Actually I would leave the getenv stuff here because the env has already been determined during the library is initialized. I mean, the global variable is constructed.

302

Well, that is what it is. We could probably think how to improve it later.

368

But here EnvStr are used twice...You would like to have two local variables? :-)

1045

You mean take the validation from isValidDeviceId to this function?

[tianshilei1992]

Update patch accordingly

[tianshilei1992]

Use back omptarget_device_environmentTy to align with deviceRTLs

[jdoerfert]

openmp/libomptarget/plugins/cuda/src/rtl.cpp

90

I figured it was not you, just that it seems weird. I should have made that clearer.

118

If we need a "common/gpu" header we can do that as well. AMD will at least look similar enough to reuse the same code. They have some "context" even if it is a class we define in the AMD headers. You can even go as far and make

common/Device.h with the entries you mentioned and then common/GPUDevice.h with the template class template<typename CtxTy> GPUDeviceDataTy : public DeviceDataTy.

173

OK

368

If you do what I described the lifetime is limited to the conditional. There will be two variables, distinct but with the same name. That is for different reasons preferable, e.g., the variable is not available outside the conditional and it is not reused. Overall it is less complex.

1045

I mean it is good to have the asserts here as that is where user provide input which we can validate. I'd leave it as it is in this version.

[tianshilei1992]

openmp/libomptarget/plugins/cuda/src/rtl.cpp

118

This part is worth a new patch. Let's do it in next step.

[tianshilei1992]

Updated patch accordingly

[jdoerfert]

I assume you tested this locally and it works as expected? If so, I think we can go ahead. One comment to address now below.

openmp/libomptarget/plugins/cuda/src/rtl.cpp

256

We check already in resizeStreamPool. Just return if it worked or not there.

881–882

You can make checkResult variadic in a separate commit to reuse it here. It could even be a macro if that makes it easier.

[tianshilei1992]

openmp/libomptarget/plugins/cuda/src/rtl.cpp

256

Actually the failure in resizeStreamPool will not impact its return. Those checks would only print out some messages but not aborting the program. Actually, I'm very not sure whether we need to abort the whole program as long as one CUDA operation returns error. From my point of view, I think we should. WDYT?

881–882

Actually I'm thinking to improve it. Will do in another patch.

[tianshilei1992]

Fixed a tiny compilation error

[tianshilei1992]

In D77951#1977061, @jdoerfert wrote:

I assume you tested this locally and it works as expected? If so, I think we can go ahead. One comment to address now below.

Yep. I tested all unit tests and two benchmarks. Worked as expected.

openmp/libomptarget/include/omptarget.h

 
 #ifndef _OMPTARGET_H_
 #define _OMPTARGET_H_
 
 #include <stdint.h>
 #include <stddef.h>
 
 #define OFFLOAD_SUCCESS (0)
-#define OFFLOAD_FAIL (~0)
+#define OFFLOAD_FAIL (~0U)
 
 #define OFFLOAD_DEVICE_DEFAULT     -1
 #define HOST_DEVICE                -10
 
 /// Data attributes for each data reference used in an OpenMP target region.
 enum tgt_map_type {
   // No flags
   OMP_TGT_MAPTYPE_NONE            = 0x000,

openmp/libomptarget/plugins/cuda/src/rtl.cpp

 #define TARGET_NAME CUDA
 #endif
 
 #ifdef OMPTARGET_DEBUG
 static int DebugLevel = 0;
 
 #define GETNAME2(name) #name
 #define GETNAME(name) GETNAME2(name)
-#define DP(...) \
-  do { \
-    if (DebugLevel > 0) { \
-      DEBUGP("Target " GETNAME(TARGET_NAME) " RTL", __VA_ARGS__); \
-    } \
+#define DP(...)                                                                \
+  do {                                                                         \
+    if (DebugLevel > 0) {                                                      \
+      DEBUGP("Target " GETNAME(TARGET_NAME) " RTL", __VA_ARGS__);              \
+    }                                                                          \
   } while (false)
 
 // Utility for retrieving and printing CUDA error string.
-#define CUDA_ERR_STRING(err) \
-  do { \
-    if (DebugLevel > 0) { \
-      const char *errStr; \
-      cuGetErrorString(err, &errStr); \
-      DEBUGP("Target " GETNAME(TARGET_NAME) " RTL", "CUDA error is: %s\n", errStr); \
-    } \
+#define CUDA_ERR_STRING(err)                                                   \
+  do {                                                                         \
+    if (DebugLevel > 0) {                                                      \
+      const char *errStr;                                                      \
+      cuGetErrorString(err, &errStr);                                          \
+      DEBUGP("Target " GETNAME(TARGET_NAME) " RTL", "CUDA error is: %s\n",     \
+             errStr);                                                          \
+    }                                                                          \
   } while (false)
 #else // OMPTARGET_DEBUG
-#define DP(...) {}
-#define CUDA_ERR_STRING(err) {}
+#define DP(...)                                                                \
+  {}
+#define CUDA_ERR_STRING(err)                                                   \
+  {}
 #endif // OMPTARGET_DEBUG
 
 #include "../../common/elf_common.c"
 
+namespace {
 /// Keep entries table per device.
 struct FuncOrGblEntryTy {
   __tgt_target_table Table;
   std::vector<__tgt_offload_entry> Entries;
 };
 
 enum ExecutionModeType {
-  SPMD, // constructors, destructors,
-        // combined constructs (`teams distribute parallel for [simd]`)
+  SPMD,    // constructors, destructors, combined constructs (`teams distribute
+           // parallel for [simd]`)
   GENERIC, // everything else
   NONE
 };
 
 /// Use a single entity to encode a kernel and a set of flags.
 struct KernelTy {
   CUfunction Func;
 
   // execution mode of kernel
   // 0 - SPMD mode (without master warp)
   // 1 - Generic mode (with master warp)
   int8_t ExecutionMode;
 
   KernelTy(CUfunction _Func, int8_t _ExecutionMode)
       : Func(_Func), ExecutionMode(_ExecutionMode) {}
 };
 
+/// List that contains all the kernels.
+/// FIXME: we may need this to be per device and per library.
+std::list<KernelTy> KernelsList;
+
 /// Device environment data
 /// Manually sync with the deviceRTL side for now, move to a dedicated header
 /// file later.
-struct omptarget_device_environmentTy {
-  int32_t debug_level;
+struct OMPTargetDeviceEnvironmentTy {
+  int DebugLevel = 0;
 };
 
-/// List that contains all the kernels.
-/// FIXME: we may need this to be per device and per library.
-std::list<KernelTy> KernelsList;
-
-namespace {
 bool checkResult(CUresult Err, const char *ErrMsg) {
   if (Err == CUDA_SUCCESS)
     return true;
 
   DP(ErrMsg);
   CUDA_ERR_STRING(Err);
   return false;
 }
-} // namespace
+
+// Structure contains per-device data
+struct DeviceDataTy {
+  std::list<FuncOrGblEntryTy> FuncGblEntries;
+  CUcontext Context = nullptr;
+  // Device properties
+  int ThreadsPerBlock = 0;
+  int BlocksPerGrid = 0;
+  int WarpSize = 0;
+  // OpenMP properties
+  int NumTeams = 0;
+  int NumThreads = 0;
+};
 
 class StreamManagerTy {
   int NumberOfDevices;
+  // The initial size of stream pool
+  int EnvNumInitialStreams;
   // Per-device stream mutex
   std::vector<std::unique_ptr<std::mutex>> StreamMtx;
   // Per-device stream Id indicates the next available stream in the pool
   std::vector<int> NextStreamId;
   // Per-device stream pool
   std::vector<std::vector<CUstream>> StreamPool;
-  // Pointer to per-device context
-  std::vector<CUcontext> &ContextsPtr;
+  // Reference to per-device data
+  std::vector<DeviceDataTy> &DeviceData;
 
   // If there is no CUstream left in the pool, we will resize the pool to
   // allocate more CUstream. This function should be called with device mutex,
   // and we do not resize to smaller one.
   void resizeStreamPool(const int DeviceId, const size_t NewSize) {
     std::vector<CUstream> &Pool = StreamPool[DeviceId];
     const size_t CurrentSize = Pool.size();
     assert(NewSize > CurrentSize && "new size is not larger than current size");
 
-    Pool.resize(NewSize, nullptr);
-
-    CUresult err = cuCtxSetCurrent(ContextsPtr[DeviceId]);
-    if (!checkResult(err, "Error when setting current CUDA context\n")) {
+    CUresult Err = cuCtxSetCurrent(DeviceData[DeviceId].Context);
+    if (!checkResult(Err, "Error returned from cuCtxSetCurrent\n")) {
       // We will return if cannot switch to the right context in case of
       // creating bunch of streams that are not corresponding to the right
       // device. The offloading will fail later because selected CUstream is
       // nullptr.
       return;
     }
 
+    Pool.resize(NewSize, nullptr);
+
     for (size_t I = CurrentSize; I < NewSize; ++I) {
-      err = cuStreamCreate(&Pool[I], CU_STREAM_NON_BLOCKING);
-      checkResult(err,
-                  "Error when creating CUDA stream to resize stream pool\n");
+      checkResult(cuStreamCreate(&Pool[I], CU_STREAM_NON_BLOCKING),
+                  "Error returned from cuStreamCreate\n");
     }
   }
 
 public:
-  StreamManagerTy(const int NumberOfDevices, std::vector<CUcontext> &CtxPtr)
-      : NumberOfDevices(NumberOfDevices), ContextsPtr(CtxPtr) {
+  StreamManagerTy(const int NumberOfDevices,
+                  std::vector<DeviceDataTy> &DeviceData)
+      : NumberOfDevices(NumberOfDevices), EnvNumInitialStreams(32),
+        DeviceData(DeviceData) {
     StreamPool.resize(NumberOfDevices);
     NextStreamId.resize(NumberOfDevices);
     StreamMtx.resize(NumberOfDevices);
 
-    // Initially let's create 32 streams for each device
-    int EnvNumInitialStreams = 32;
-    char *envStr = getenv("LIBOMPTARGET_NUM_INITIAL_STREAMS");
-    if (envStr)
-      EnvNumInitialStreams = std::stoi(envStr);
+    char *EnvStr = getenv("LIBOMPTARGET_NUM_INITIAL_STREAMS");
+    if (EnvStr)
+      EnvNumInitialStreams = std::stoi(EnvStr);
 
-    // Initialize the stream pool for each device
+    // Reserve the size for stream pool of each device
     for (std::vector<CUstream> &S : StreamPool)
-      S.resize(EnvNumInitialStreams);
+      S.reserve(EnvNumInitialStreams);
 
     // Initialize the next stream id
     std::fill(NextStreamId.begin(), NextStreamId.end(), 0);
 
     // Initialize stream mutex
     for (std::unique_ptr<std::mutex> &Ptr : StreamMtx)
       Ptr = std::make_unique<std::mutex>();
   }
 
   ~StreamManagerTy() {
     // Destroy streams
     for (int I = 0; I < NumberOfDevices; ++I) {
-      CUresult err = cuCtxSetCurrent(ContextsPtr[I]);
-      checkResult(err, "Error when setting current CUDA context\n");
+      checkResult(cuCtxSetCurrent(DeviceData[I].Context),
+                  "Error returned from cuCtxSetCurrent\n");
 
       for (CUstream &S : StreamPool[I]) {
-        if (!S)
-          continue;
-        err = cuStreamDestroy(S);
-        checkResult(err, "Error when destroying CUDA stream\n");
+        if (S)
+          checkResult(cuStreamDestroy(S),
+                      "Error returned from cuStreamDestroy\n");
       }
     }
   }
 
   // Get a CUstream from pool. Per-device next stream id always points to the
   // next available CUstream. That means, CUstreams [0, id-1] have been
   // assigned, and [id,] are still available. If there is no CUstream left, we
   // will ask more CUstreams from CUDA RT. Each time a CUstream is assigned,
   // the id will increase one.
   // xxxxxs+++++++++
   //      ^
   //      id
   // After assignment, the pool becomes the following and s is assigned.
   // xxxxxs+++++++++
   //       ^
   //       id
   CUstream getStream(const int DeviceId) {
-    assert(DeviceId >= 0 &&
-           static_cast<size_t>(DeviceId) < NextStreamId.size() &&
-           "Unexpected device id");
-
     const std::lock_guard<std::mutex> Lock(*StreamMtx[DeviceId]);
     int &Id = NextStreamId[DeviceId];
     // No CUstream left in the pool, we need to request from CUDA RT
     if (Id == StreamPool[DeviceId].size()) {
       // By default we double the stream pool every time
       resizeStreamPool(DeviceId, Id * 2);
     }
     return StreamPool[DeviceId][Id++];
public:
   // xxax+a+++++
   //     ^
   //     id
   // However, it doesn't matter, because they're always on the two sides of
   // id. The left one will in the end be overwritten by another CUstream.
   // Therefore, after several execution, the order of pool might be different
   // from its initial state.
   void returnStream(const int DeviceId, CUstream Stream) {
-    assert(DeviceId >= 0 &&
-           static_cast<size_t>(DeviceId) < NextStreamId.size() &&
-           "Unexpected device id");
-
     const std::lock_guard<std::mutex> Lock(*StreamMtx[DeviceId]);
     int &Id = NextStreamId[DeviceId];
     assert(Id > 0 && "Wrong stream ID");
     StreamPool[DeviceId][--Id] = Stream;
   }
 
-  void initializeDevice(int DeviceId) {
-    // This function should be called after setting right context
-    for (CUstream &Stream : StreamPool[DeviceId]) {
-      CUresult Err = cuStreamCreate(&Stream, CU_STREAM_NON_BLOCKING);
-      checkResult(Err, "Error when creating CUDA stream\n");
-    }
-  }
-};
+  bool initializeDeviceStreamPool(const int DeviceId) {
+    assert(StreamPool[DeviceId].empty() && "stream pool has been initialized");
 
-/// Class containing all the device information.
-class RTLDeviceInfoTy {
-  std::vector<std::list<FuncOrGblEntryTy>> FuncGblEntries;
-  std::shared_ptr<StreamManagerTy> StreamManager;
+    resizeStreamPool(DeviceId, EnvNumInitialStreams);
 
-public:
-  int NumberOfDevices;
-  std::vector<CUmodule> Modules;
-  std::vector<CUcontext> Contexts;
+    // Check the size of stream pool
+    if (StreamPool[DeviceId].size() != EnvNumInitialStreams)
+      return false;
 
-  // Device properties
-  std::vector<int> ThreadsPerBlock;
-  std::vector<int> BlocksPerGrid;
-  std::vector<int> WarpSize;
+    // Check whether each stream is valid
+    for (CUstream &S : StreamPool[DeviceId])
+      if (!S)
+        return false;
 
-  // OpenMP properties
-  std::vector<int> NumTeams;
-  std::vector<int> NumThreads;
+    return true;
+  }
+};
 
-  // OpenMP Environment properties
+class DeviceRTLTy {
+  int NumberOfDevices;
+  // OpenMP environment properties
   int EnvNumTeams;
   int EnvTeamLimit;
-
-  // OpenMP Requires Flags
+  // OpenMP requires flags
   int64_t RequiresFlags;
 
-  // static int EnvNumThreads;
-  static const int HardTeamLimit = 1 << 16; // 64k
-  static const int HardThreadLimit = 1024;
-  static const int DefaultNumTeams = 128;
-  static const int DefaultNumThreads = 128;
-
-  std::shared_ptr<StreamManagerTy> getStreamManager() { return StreamManager; }
-
-  CUstream getStream(const int DeviceId) {
-    return StreamManager->getStream(DeviceId);
-  }
+  static constexpr const int HardTeamLimit = 1U << 16U; // 64k
+  static constexpr const int HardThreadLimit = 1024;
+  static constexpr const int DefaultNumTeams = 128;
+  static constexpr const int DefaultNumThreads = 128;
 
-  void returnStream(const int DeviceId, __tgt_async_info *AsyncInfoPtr) {
-    assert(AsyncInfoPtr && "AsyncInfoPtr is nullptr");
-    assert(AsyncInfoPtr->Queue && "AsyncInfoPtr->Queue is nullptr");
-
-    StreamManager->returnStream(
-        DeviceId, reinterpret_cast<CUstream>(AsyncInfoPtr->Queue));
-    AsyncInfoPtr->Queue = nullptr;
-  }
+  std::unique_ptr<StreamManagerTy> StreamManager;
+  std::vector<DeviceDataTy> DeviceData;
+  std::vector<CUmodule> Modules;
 
   // Record entry point associated with device
-  void addOffloadEntry(int32_t device_id, __tgt_offload_entry entry) {
-    assert(device_id < (int32_t)FuncGblEntries.size() &&
-           "Unexpected device id!");
-    FuncOrGblEntryTy &E = FuncGblEntries[device_id].back();
-
+  void addOffloadEntry(const int DeviceId, const __tgt_offload_entry entry) {
+    FuncOrGblEntryTy &E = DeviceData[DeviceId].FuncGblEntries.back();
     E.Entries.push_back(entry);
   }
 
   // Return true if the entry is associated with device
-  bool findOffloadEntry(int32_t device_id, void *addr) {
-    assert(device_id < (int32_t)FuncGblEntries.size() &&
-           "Unexpected device id!");
-    FuncOrGblEntryTy &E = FuncGblEntries[device_id].back();
+  bool findOffloadEntry(const int DeviceId, const void *Addr) const {
+    const FuncOrGblEntryTy &E = DeviceData[DeviceId].FuncGblEntries.back();
 
-    for (auto &it : E.Entries) {
-      if (it.addr == addr)
+    for (const __tgt_offload_entry &it : E.Entries)
+      if (it.addr == Addr)
         return true;
-    }
 
     return false;
   }
 
   // Return the pointer to the target entries table
-  __tgt_target_table *getOffloadEntriesTable(int32_t device_id) {
-    assert(device_id < (int32_t)FuncGblEntries.size() &&
-           "Unexpected device id!");
-    FuncOrGblEntryTy &E = FuncGblEntries[device_id].back();
-
-    int32_t size = E.Entries.size();
-
-    // Table is empty
-    if (!size)
-      return 0;
+  __tgt_target_table *getOffloadEntriesTable(const int DeviceId) {
+    FuncOrGblEntryTy &E = DeviceData[DeviceId].FuncGblEntries.back();
 
-    __tgt_offload_entry *begin = &E.Entries[0];
-    __tgt_offload_entry *end = &E.Entries[size - 1];
+    if (E.Entries.empty())
+      return nullptr;
 
     // Update table info according to the entries and return the pointer
-    E.Table.EntriesBegin = begin;
-    E.Table.EntriesEnd = ++end;
+    E.Table.EntriesBegin = E.Entries.data();
+    E.Table.EntriesEnd = E.Entries.data() + E.Entries.size();
 
     return &E.Table;
   }
 
   // Clear entries table for a device
-  void clearOffloadEntriesTable(int32_t device_id) {
-    assert(device_id < (int32_t)FuncGblEntries.size() &&
-           "Unexpected device id!");
-    FuncGblEntries[device_id].emplace_back();
-    FuncOrGblEntryTy &E = FuncGblEntries[device_id].back();
+  void clearOffloadEntriesTable(const int DeviceId) {
+    DeviceData[DeviceId].FuncGblEntries.emplace_back();
+    FuncOrGblEntryTy &E = DeviceData[DeviceId].FuncGblEntries.back();
     E.Entries.clear();
-    E.Table.EntriesBegin = E.Table.EntriesEnd = 0;
+    E.Table.EntriesBegin = E.Table.EntriesEnd = nullptr;
   }
 
-  RTLDeviceInfoTy() {
-#ifdef OMPTARGET_DEBUG
-    if (char *envStr = getenv("LIBOMPTARGET_DEBUG")) {
-      DebugLevel = std::stoi(envStr);
-    }
+  CUstream getStream(const int DeviceId, __tgt_async_info *AsyncInfoPtr) const {
+    assert(AsyncInfoPtr && "AsyncInfoPtr is nullptr");
+
+    if (!AsyncInfoPtr->Queue)
+      AsyncInfoPtr->Queue = StreamManager->getStream(DeviceId);
+
+    return reinterpret_cast<CUstream>(AsyncInfoPtr->Queue);
+
+public:
+  // This class should not be copied
+  DeviceRTLTy(const DeviceRTLTy &) = delete;
+  DeviceRTLTy(DeviceRTLTy &&) = delete;
+
+  DeviceRTLTy()
+      : NumberOfDevices(0), EnvNumTeams(-1), EnvTeamLimit(-1),
+        RequiresFlags(OMP_REQ_UNDEFINED) {
+#ifdef OMPTARGET_DEBUG
+    if (const char *EnvStr = getenv("LIBOMPTARGET_DEBUG"))
+      DebugLevel = std::stoi(EnvStr);
 #endif // OMPTARGET_DEBUG
 
     DP("Start initializing CUDA\n");
 
-    CUresult err = cuInit(0);
-    if (err != CUDA_SUCCESS) {
-      DP("Error when initializing CUDA\n");
-      CUDA_ERR_STRING(err);
+    CUresult Err = cuInit(0);
+    if (!checkResult(Err, "Error returned from cuInit\n")) {
       return;
     }
 
-    NumberOfDevices = 0;
-
-    err = cuDeviceGetCount(&NumberOfDevices);
-    if (err != CUDA_SUCCESS) {
-      DP("Error when getting CUDA device count\n");
-      CUDA_ERR_STRING(err);
+    Err = cuDeviceGetCount(&NumberOfDevices);
+    if (!checkResult(Err, "Error returned from cuDeviceGetCount\n")) {
       return;
     }
 
     if (NumberOfDevices == 0) {
       DP("There are no devices supporting CUDA.\n");
       return;
     }
 
-    FuncGblEntries.resize(NumberOfDevices);
-    Contexts.resize(NumberOfDevices);
-    ThreadsPerBlock.resize(NumberOfDevices);
-    BlocksPerGrid.resize(NumberOfDevices);
-    WarpSize.resize(NumberOfDevices);
-    NumTeams.resize(NumberOfDevices);
-    NumThreads.resize(NumberOfDevices);
+    DeviceData.resize(NumberOfDevices);
 
     // Get environment variables regarding teams
-    char *envStr = getenv("OMP_TEAM_LIMIT");
-    if (envStr) {
+    const char *EnvStr = getenv("OMP_TEAM_LIMIT");
+    if (EnvStr) {
       // OMP_TEAM_LIMIT has been set
-      EnvTeamLimit = std::stoi(envStr);
+      EnvTeamLimit = std::stoi(EnvStr);
       DP("Parsed OMP_TEAM_LIMIT=%d\n", EnvTeamLimit);
-    } else {
-      EnvTeamLimit = -1;
     }
-    envStr = getenv("OMP_NUM_TEAMS");
-    if (envStr) {
+    EnvStr = getenv("OMP_NUM_TEAMS");
+    if (EnvStr) {
       // OMP_NUM_TEAMS has been set
-      EnvNumTeams = std::stoi(envStr);
+      EnvNumTeams = std::stoi(EnvStr);
       DP("Parsed OMP_NUM_TEAMS=%d\n", EnvNumTeams);
-    } else {
-      EnvNumTeams = -1;
     }
 
     StreamManager =
-        std::make_shared<StreamManagerTy>(NumberOfDevices, Contexts);
-
-    // Default state.
-    RequiresFlags = OMP_REQ_UNDEFINED;
+        std::make_unique<StreamManagerTy>(NumberOfDevices, DeviceData);
   }
 
-  ~RTLDeviceInfoTy() {
+  ~DeviceRTLTy() {
     // First destruct stream manager in case of Contexts is destructed before it
     StreamManager = nullptr;
 
-    // Close modules
-    for (auto &module : Modules)
-      if (module) {
-        CUresult err = cuModuleUnload(module);
-        if (err != CUDA_SUCCESS) {
-          DP("Error when unloading CUDA module\n");
-          CUDA_ERR_STRING(err);
-        }
-      }
+    for (CUmodule &M : Modules)
+      // Close module
+      if (M)
+        checkResult(cuModuleUnload(M), "Error returned from cuModuleUnload\n");
 
-    // Destroy contexts
-    for (auto &ctx : Contexts)
-      if (ctx) {
-        CUresult err = cuCtxDestroy(ctx);
-        if (err != CUDA_SUCCESS) {
-          DP("Error when destroying CUDA context\n");
-          CUDA_ERR_STRING(err);
-        }
-      }
+    for (DeviceDataTy &D : DeviceData) {
+      // Destroy context
+      if (D.Context)
+        checkResult(cuCtxDestroy(D.Context),
+                    "Error returned from cuCtxDestroy\n");
   }
-};
-
-static RTLDeviceInfoTy DeviceInfo;
 
-namespace {
-CUstream getStream(int32_t DeviceId, __tgt_async_info *AsyncInfoPtr) {
-  assert(AsyncInfoPtr && "AsyncInfoPtr is nullptr");
-
-  if (!AsyncInfoPtr->Queue)
-    AsyncInfoPtr->Queue = DeviceInfo.getStream(DeviceId);
-
-  return reinterpret_cast<CUstream>(AsyncInfoPtr->Queue);
+  // Check whether a given DeviceId is valid
+  bool isValidDeviceId(const int DeviceId) const {
+    return DeviceId >= 0 && DeviceId < NumberOfDevices;
   }
 
-int32_t dataRetrieve(int32_t DeviceId, void *HstPtr, void *TgtPtr, int64_t Size,
-                     __tgt_async_info *AsyncInfoPtr) {
-  assert(AsyncInfoPtr && "AsyncInfoPtr is nullptr");
-  // Set the context we are using.
-  CUresult err = cuCtxSetCurrent(DeviceInfo.Contexts[DeviceId]);
-  if (err != CUDA_SUCCESS) {
-    DP("Error when setting CUDA context\n");
-    CUDA_ERR_STRING(err);
-    return OFFLOAD_FAIL;
-  }
+  bool getNumOfDevices() const { return NumberOfDevices; }
 
-  CUstream Stream = getStream(DeviceId, AsyncInfoPtr);
+  void setRequiresFlag(const int64_t Flags) { this->RequiresFlags = Flags; }
 
-  err = cuMemcpyDtoHAsync(HstPtr, (CUdeviceptr)TgtPtr, Size, Stream);
-  if (err != CUDA_SUCCESS) {
-    DP("Error when copying data from device to host. Pointers: host = " DPxMOD
-       ", device = " DPxMOD ", size = %" PRId64 "\n",
-       DPxPTR(HstPtr), DPxPTR(TgtPtr), Size);
-    CUDA_ERR_STRING(err);
-    return OFFLOAD_FAIL;
-  }
+  int initDevice(const int DeviceId) {
+    CUdevice Device;
 
-  return OFFLOAD_SUCCESS;
-}
-
-int32_t dataSubmit(int32_t DeviceId, void *TgtPtr, void *HstPtr, int64_t Size,
-                   __tgt_async_info *AsyncInfoPtr) {
-  assert(AsyncInfoPtr && "AsyncInfoPtr is nullptr");
-  // Set the context we are using.
-  CUresult err = cuCtxSetCurrent(DeviceInfo.Contexts[DeviceId]);
-  if (err != CUDA_SUCCESS) {
-    DP("Error when setting CUDA context\n");
-    CUDA_ERR_STRING(err);
-    return OFFLOAD_FAIL;
-  }
-
-  CUstream Stream = getStream(DeviceId, AsyncInfoPtr);
-
-  err = cuMemcpyHtoDAsync((CUdeviceptr)TgtPtr, HstPtr, Size, Stream);
-  if (err != CUDA_SUCCESS) {
-    DP("Error when copying data from host to device. Pointers: host = " DPxMOD
-       ", device = " DPxMOD ", size = %" PRId64 "\n",
-       DPxPTR(HstPtr), DPxPTR(TgtPtr), Size);
-    CUDA_ERR_STRING(err);
-    return OFFLOAD_FAIL;
-  }
-
-  return OFFLOAD_SUCCESS;
-}
-} // namespace
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-int32_t __tgt_rtl_is_valid_binary(__tgt_device_image *image) {
-  return elf_check_machine(image, 190); // EM_CUDA = 190.
-}
-
-int32_t __tgt_rtl_number_of_devices() { return DeviceInfo.NumberOfDevices; }
-
-int64_t __tgt_rtl_init_requires(int64_t RequiresFlags) {
-  DP("Init requires flags to %ld\n", RequiresFlags);
-  DeviceInfo.RequiresFlags = RequiresFlags;
-  return RequiresFlags;
-}
-
-int32_t __tgt_rtl_init_device(int32_t device_id) {
-
-  CUdevice cuDevice;
-  DP("Getting device %d\n", device_id);
-  CUresult err = cuDeviceGet(&cuDevice, device_id);
-  if (err != CUDA_SUCCESS) {
-    DP("Error when getting CUDA device with id = %d\n", device_id);
-    CUDA_ERR_STRING(err);
+    DP("Getting device %d\n", DeviceId);
+    CUresult Err = cuDeviceGet(&Device, DeviceId);
+    if (!checkResult(Err, "Error returned from cuDeviceGet\n"))
       return OFFLOAD_FAIL;
-  }
 
     // Create the context and save it to use whenever this device is selected.
-  err = cuCtxCreate(&DeviceInfo.Contexts[device_id], CU_CTX_SCHED_BLOCKING_SYNC,
-                    cuDevice);
-  if (err != CUDA_SUCCESS) {
-    DP("Error when creating a CUDA context\n");
-    CUDA_ERR_STRING(err);
+    Err = cuCtxCreate(&DeviceData[DeviceId].Context, CU_CTX_SCHED_BLOCKING_SYNC,
+                      Device);
+    if (!checkResult(Err, "Error returned from cuCtxCreate\n"))
       return OFFLOAD_FAIL;
-  }
 
-  err = cuCtxSetCurrent(DeviceInfo.Contexts[device_id]);
-  if (err != CUDA_SUCCESS) {
-    DP("Error when setting current CUDA context\n");
-    CUDA_ERR_STRING(err);
-  }
+    Err = cuCtxSetCurrent(DeviceData[DeviceId].Context);
+    if (!checkResult(Err, "Error returned from cuCtxSetCurrent\n"))
+      return OFFLOAD_FAIL;
 
     // Initialize stream pool
-  DeviceInfo.getStreamManager()->initializeDevice(device_id);
+    if (!StreamManager->initializeDeviceStreamPool(DeviceId))
+      return OFFLOAD_FAIL;
 
     // Query attributes to determine number of threads/block and blocks/grid.
-  int maxGridDimX;
-  err = cuDeviceGetAttribute(&maxGridDimX, CU_DEVICE_ATTRIBUTE_MAX_GRID_DIM_X,
-                             cuDevice);
-  if (err != CUDA_SUCCESS) {
-    DP("Error getting max grid dimension, use default\n");
-    DeviceInfo.BlocksPerGrid[device_id] = RTLDeviceInfoTy::DefaultNumTeams;
-  } else if (maxGridDimX <= RTLDeviceInfoTy::HardTeamLimit) {
-    DeviceInfo.BlocksPerGrid[device_id] = maxGridDimX;
-    DP("Using %d CUDA blocks per grid\n", maxGridDimX);
+    int MaxGridDimX;
+    Err = cuDeviceGetAttribute(&MaxGridDimX, CU_DEVICE_ATTRIBUTE_MAX_GRID_DIM_X,
+                               Device);
+    if (Err != CUDA_SUCCESS) {
+      DP("Error getting max grid dimension, use default value %d\n",
+         DeviceRTLTy::DefaultNumTeams);
+      DeviceData[DeviceId].BlocksPerGrid = DeviceRTLTy::DefaultNumTeams;
+    } else if (MaxGridDimX <= DeviceRTLTy::HardTeamLimit) {
+      DP("Using %d CUDA blocks per grid\n", MaxGridDimX);
+      DeviceData[DeviceId].BlocksPerGrid = MaxGridDimX;
     } else {
-    DeviceInfo.BlocksPerGrid[device_id] = RTLDeviceInfoTy::HardTeamLimit;
       DP("Max CUDA blocks per grid %d exceeds the hard team limit %d, capping "
          "at the hard limit\n",
-       maxGridDimX, RTLDeviceInfoTy::HardTeamLimit);
+         MaxGridDimX, DeviceRTLTy::HardTeamLimit);
+      DeviceData[DeviceId].BlocksPerGrid = DeviceRTLTy::HardTeamLimit;
     }
 
     // We are only exploiting threads along the x axis.
-  int maxBlockDimX;
-  err = cuDeviceGetAttribute(&maxBlockDimX, CU_DEVICE_ATTRIBUTE_MAX_BLOCK_DIM_X,
-                             cuDevice);
-  if (err != CUDA_SUCCESS) {
-    DP("Error getting max block dimension, use default\n");
-    DeviceInfo.ThreadsPerBlock[device_id] = RTLDeviceInfoTy::DefaultNumThreads;
-  } else if (maxBlockDimX <= RTLDeviceInfoTy::HardThreadLimit) {
-    DeviceInfo.ThreadsPerBlock[device_id] = maxBlockDimX;
-    DP("Using %d CUDA threads per block\n", maxBlockDimX);
+    int MaxBlockDimX;
+    Err = cuDeviceGetAttribute(&MaxBlockDimX,
+                               CU_DEVICE_ATTRIBUTE_MAX_BLOCK_DIM_X, Device);
+    if (Err != CUDA_SUCCESS) {
+      DP("Error getting max block dimension, use default value %d\n",
+         DeviceRTLTy::DefaultNumThreads);
+      DeviceData[DeviceId].ThreadsPerBlock = DeviceRTLTy::DefaultNumThreads;
+    } else if (MaxBlockDimX <= DeviceRTLTy::HardThreadLimit) {
+      DP("Using %d CUDA threads per block\n", MaxBlockDimX);
+      DeviceData[DeviceId].ThreadsPerBlock = MaxBlockDimX;
     } else {
-    DeviceInfo.ThreadsPerBlock[device_id] = RTLDeviceInfoTy::HardThreadLimit;
-    DP("Max CUDA threads per block %d exceeds the hard thread limit %d, capping"
-       "at the hard limit\n",
-       maxBlockDimX, RTLDeviceInfoTy::HardThreadLimit);
+      DP("Max CUDA threads per block %d exceeds the hard thread limit %d, "
+         "capping at the hard limit\n",
+         MaxBlockDimX, DeviceRTLTy::HardThreadLimit);
+      DeviceData[DeviceId].ThreadsPerBlock = DeviceRTLTy::HardThreadLimit;
     }
 
-  int warpSize;
-  err =
-      cuDeviceGetAttribute(&warpSize, CU_DEVICE_ATTRIBUTE_WARP_SIZE, cuDevice);
-  if (err != CUDA_SUCCESS) {
-    DP("Error getting warp size, assume default\n");
-    DeviceInfo.WarpSize[device_id] = 32;
+    // Get and set warp size
+    int WarpSize;
+    Err =
+        cuDeviceGetAttribute(&WarpSize, CU_DEVICE_ATTRIBUTE_WARP_SIZE, Device);
+    if (Err != CUDA_SUCCESS) {
+      DP("Error getting warp size, assume default value 32\n");
+      DeviceData[DeviceId].WarpSize = 32;
     } else {
-    DeviceInfo.WarpSize[device_id] = warpSize;
+      DP("Using warp size %d\n", WarpSize);
+      DeviceData[DeviceId].WarpSize = WarpSize;
     }
 
     // Adjust teams to the env variables
-  if (DeviceInfo.EnvTeamLimit > 0 &&
-      DeviceInfo.BlocksPerGrid[device_id] > DeviceInfo.EnvTeamLimit) {
-    DeviceInfo.BlocksPerGrid[device_id] = DeviceInfo.EnvTeamLimit;
+    if (EnvTeamLimit > 0 && DeviceData[DeviceId].BlocksPerGrid > EnvTeamLimit) {
       DP("Capping max CUDA blocks per grid to OMP_TEAM_LIMIT=%d\n",
-        DeviceInfo.EnvTeamLimit);
+         EnvTeamLimit);
+      DeviceData[DeviceId].BlocksPerGrid = EnvTeamLimit;
     }
 
     DP("Max number of CUDA blocks %d, threads %d & warp size %d\n",
-     DeviceInfo.BlocksPerGrid[device_id], DeviceInfo.ThreadsPerBlock[device_id],
-     DeviceInfo.WarpSize[device_id]);
+       DeviceData[DeviceId].BlocksPerGrid, DeviceData[DeviceId].ThreadsPerBlock,
+       DeviceData[DeviceId].WarpSize);
 
     // Set default number of teams
-  if (DeviceInfo.EnvNumTeams > 0) {
-    DeviceInfo.NumTeams[device_id] = DeviceInfo.EnvNumTeams;
+    if (EnvNumTeams > 0) {
       DP("Default number of teams set according to environment %d\n",
-        DeviceInfo.EnvNumTeams);
+         EnvNumTeams);
+      DeviceData[DeviceId].NumTeams = EnvNumTeams;
     } else {
-    DeviceInfo.NumTeams[device_id] = RTLDeviceInfoTy::DefaultNumTeams;
+      DeviceData[DeviceId].NumTeams = DeviceRTLTy::DefaultNumTeams;
       DP("Default number of teams set according to library's default %d\n",
-        RTLDeviceInfoTy::DefaultNumTeams);
+         DeviceRTLTy::DefaultNumTeams);
     }
-  if (DeviceInfo.NumTeams[device_id] > DeviceInfo.BlocksPerGrid[device_id]) {
-    DeviceInfo.NumTeams[device_id] = DeviceInfo.BlocksPerGrid[device_id];
+
+    if (DeviceData[DeviceId].NumTeams > DeviceData[DeviceId].BlocksPerGrid) {
       DP("Default number of teams exceeds device limit, capping at %d\n",
-        DeviceInfo.BlocksPerGrid[device_id]);
+         DeviceData[DeviceId].BlocksPerGrid);
+      DeviceData[DeviceId].NumTeams = DeviceData[DeviceId].BlocksPerGrid;
     }
 
     // Set default number of threads
-  DeviceInfo.NumThreads[device_id] = RTLDeviceInfoTy::DefaultNumThreads;
+    DeviceData[DeviceId].NumThreads = DeviceRTLTy::DefaultNumThreads;
     DP("Default number of threads set according to library's default %d\n",
-          RTLDeviceInfoTy::DefaultNumThreads);
-  if (DeviceInfo.NumThreads[device_id] >
-      DeviceInfo.ThreadsPerBlock[device_id]) {
-    DeviceInfo.NumTeams[device_id] = DeviceInfo.ThreadsPerBlock[device_id];
+       DeviceRTLTy::DefaultNumThreads);
+    if (DeviceData[DeviceId].NumThreads >
+        DeviceData[DeviceId].ThreadsPerBlock) {
       DP("Default number of threads exceeds device limit, capping at %d\n",
-        DeviceInfo.ThreadsPerBlock[device_id]);
+         DeviceData[DeviceId].ThreadsPerBlock);
+      DeviceData[DeviceId].NumTeams = DeviceData[DeviceId].ThreadsPerBlock;
     }
 
     return OFFLOAD_SUCCESS;
   }
 
-__tgt_target_table *__tgt_rtl_load_binary(int32_t device_id,
-    __tgt_device_image *image) {
-
-  // Set the context we are using.
-  CUresult err = cuCtxSetCurrent(DeviceInfo.Contexts[device_id]);
-  if (err != CUDA_SUCCESS) {
-    DP("Error when setting a CUDA context for device %d\n", device_id);
-    CUDA_ERR_STRING(err);
-    return NULL;
-  }
+  __tgt_target_table *loadBinary(const int DeviceId,
+                                 const __tgt_device_image *Image) {
+    // Set the context we are using
+    CUresult Err = cuCtxSetCurrent(DeviceData[DeviceId].Context);
+    if (!checkResult(Err, "Error returned from cuCtxSetCurrent\n"))
+      return nullptr;
 
     // Clear the offload table as we are going to create a new one.
-  DeviceInfo.clearOffloadEntriesTable(device_id);
+    clearOffloadEntriesTable(DeviceId);
 
     // Create the module and extract the function pointers.
-
-  CUmodule cumod;
-  DP("Load data from image " DPxMOD "\n", DPxPTR(image->ImageStart));
-  err = cuModuleLoadDataEx(&cumod, image->ImageStart, 0, NULL, NULL);
-  if (err != CUDA_SUCCESS) {
-    DP("Error when loading CUDA module\n");
-    CUDA_ERR_STRING(err);
-    return NULL;
-  }
+    CUmodule Module;
+    DP("Load data from image " DPxMOD "\n", DPxPTR(Image->ImageStart));
+    Err = cuModuleLoadDataEx(&Module, Image->ImageStart, 0, nullptr, nullptr);
+    if (!checkResult(Err, "Error returned from cuModuleLoadDataEx\n"))
+      return nullptr;
 
     DP("CUDA module successfully loaded!\n");
-  DeviceInfo.Modules.push_back(cumod);
-
-  // Find the symbols in the module by name.
-  __tgt_offload_entry *HostBegin = image->EntriesBegin;
-  __tgt_offload_entry *HostEnd = image->EntriesEnd;
-
-  for (__tgt_offload_entry *e = HostBegin; e != HostEnd; ++e) {
-
-    if (!e->addr) {
-      // We return NULL when something like this happens, the host should have
-      // always something in the address to uniquely identify the target region.
-      DP("Invalid binary: host entry '<null>' (size = %zd)...\n", e->size);
-
-      return NULL;
-    }
 
-    if (e->size) {
-      __tgt_offload_entry entry = *e;
+    Modules.push_back(Module);
 
-      CUdeviceptr cuptr;
-      size_t cusize;
-      err = cuModuleGetGlobal(&cuptr, &cusize, cumod, e->name);
+    // Find the symbols in the module by name.
+    const __tgt_offload_entry *HostBegin = Image->EntriesBegin;
+    const __tgt_offload_entry *HostEnd = Image->EntriesEnd;
 
-      if (err != CUDA_SUCCESS) {
-        DP("Loading global '%s' (Failed)\n", e->name);
-        CUDA_ERR_STRING(err);
-        return NULL;
+    for (const __tgt_offload_entry *E = HostBegin; E != HostEnd; ++E) {
+      if (!E->addr) {
+        // We return nullptr when something like this happens, the host should
+        // have always something in the address to uniquely identify the target
+        // region.
+        DP("Invalid binary: host entry '<null>' (size = %zd)...\n", E->size);
+        return nullptr;
+      }
+
+      if (E->size) {
+        __tgt_offload_entry Entry = *E;
+        CUdeviceptr CUPtr;
+        size_t CUSize;
+        Err = cuModuleGetGlobal(&CUPtr, &CUSize, Module, E->name);
+        // We keep this style here because we need the name
+        if (Err != CUDA_SUCCESS) {
+          DP("Loading global '%s' (Failed)\n", E->name);
+          CUDA_ERR_STRING(Err);
+          return nullptr;
         }
 
-      if (cusize != e->size) {
-        DP("Loading global '%s' - size mismatch (%zd != %zd)\n", e->name,
-            cusize, e->size);
-        CUDA_ERR_STRING(err);
-        return NULL;
+        if (CUSize != E->size) {
+          DP("Loading global '%s' - size mismatch (%zd != %zd)\n", E->name,
+             CUSize, E->size);
+          return nullptr;
         }
 
         DP("Entry point " DPxMOD " maps to global %s (" DPxMOD ")\n",
-          DPxPTR(e - HostBegin), e->name, DPxPTR(cuptr));
-      entry.addr = (void *)cuptr;
+           DPxPTR(E - HostBegin), E->name, DPxPTR(CUPtr));
+
+        Entry.addr = (void *)(CUPtr);
 
         // Note: In the current implementation declare target variables
         // can either be link or to. This means that once unified
         // memory is activated via the requires directive, the variable
         // can be used directly from the host in both cases.
         // TODO: when variables types other than to or link are added,
         // the below condition should be changed to explicitly
         // check for to and link variables types:
-      //  (DeviceInfo.RequiresFlags & OMP_REQ_UNIFIED_SHARED_MEMORY &&
-      //   (e->flags & OMP_DECLARE_TARGET_LINK ||
-      //    e->flags == OMP_DECLARE_TARGET_TO))
-      if (DeviceInfo.RequiresFlags & OMP_REQ_UNIFIED_SHARED_MEMORY) {
+        // (RequiresFlags & OMP_REQ_UNIFIED_SHARED_MEMORY && (e->flags &
+        // OMP_DECLARE_TARGET_LINK || e->flags == OMP_DECLARE_TARGET_TO))
+        if (RequiresFlags & OMP_REQ_UNIFIED_SHARED_MEMORY) {
           // If unified memory is present any target link or to variables
           // can access host addresses directly. There is no longer a
           // need for device copies.
-        cuMemcpyHtoD(cuptr, e->addr, sizeof(void *));
-        DP("Copy linked variable host address (" DPxMOD ")"
-           "to device address (" DPxMOD ")\n",
-          DPxPTR(*((void**)e->addr)), DPxPTR(cuptr));
+          cuMemcpyHtoD(CUPtr, E->addr, sizeof(void *));
+          DP("Copy linked variable host address (" DPxMOD
+             ") to device address (" DPxMOD ")\n",
+             DPxPTR(*((void **)E->addr)), DPxPTR(CUPtr));
         }
 
-      DeviceInfo.addOffloadEntry(device_id, entry);
+        addOffloadEntry(DeviceId, Entry);
 
         continue;
       }
 
-    CUfunction fun;
-    err = cuModuleGetFunction(&fun, cumod, e->name);
-
-    if (err != CUDA_SUCCESS) {
-      DP("Loading '%s' (Failed)\n", e->name);
-      CUDA_ERR_STRING(err);
-      return NULL;
-    }
+      CUfunction Func;
+      Err = cuModuleGetFunction(&Func, Module, E->name);
+      // TODO: Improve checkResult function using E->name
+      if (!checkResult(Err, "Error returned from cuModuleGetFunction\n"))
+        return nullptr;
 
       DP("Entry point " DPxMOD " maps to %s (" DPxMOD ")\n",
-        DPxPTR(e - HostBegin), e->name, DPxPTR(fun));
+         DPxPTR(E - HostBegin), E->name, DPxPTR(Func));
 
       // default value GENERIC (in case symbol is missing from cubin file)
       int8_t ExecModeVal = ExecutionModeType::GENERIC;
-    std::string ExecModeNameStr (e->name);
+      std::string ExecModeNameStr(E->name);
       ExecModeNameStr += "_exec_mode";
       const char *ExecModeName = ExecModeNameStr.c_str();
 
       CUdeviceptr ExecModePtr;
-    size_t cusize;
-    err = cuModuleGetGlobal(&ExecModePtr, &cusize, cumod, ExecModeName);
-    if (err == CUDA_SUCCESS) {
-      if ((size_t)cusize != sizeof(int8_t)) {
+      size_t CUSize;
+      Err = cuModuleGetGlobal(&ExecModePtr, &CUSize, Module, ExecModeName);
+      if (Err == CUDA_SUCCESS) {
+        if (CUSize != sizeof(int8_t)) {
           DP("Loading global exec_mode '%s' - size mismatch (%zd != %zd)\n",
-           ExecModeName, cusize, sizeof(int8_t));
-        CUDA_ERR_STRING(err);
-        return NULL;
+             ExecModeName, CUSize, sizeof(int8_t));
+          return nullptr;
         }
 
-      err = cuMemcpyDtoH(&ExecModeVal, ExecModePtr, cusize);
-      if (err != CUDA_SUCCESS) {
+        Err = cuMemcpyDtoH(&ExecModeVal, ExecModePtr, CUSize);
+        // TODO: Improve checkResult function using E->name
+        if (Err != CUDA_SUCCESS) {
           DP("Error when copying data from device to host. Pointers: "
              "host = " DPxMOD ", device = " DPxMOD ", size = %zd\n",
-           DPxPTR(&ExecModeVal), DPxPTR(ExecModePtr), cusize);
-        CUDA_ERR_STRING(err);
-        return NULL;
+             DPxPTR(&ExecModeVal), DPxPTR(ExecModePtr), CUSize);
+          CUDA_ERR_STRING(Err);
+          return nullptr;
         }
 
         if (ExecModeVal < 0 || ExecModeVal > 1) {
           DP("Error wrong exec_mode value specified in cubin file: %d\n",
              ExecModeVal);
-        return NULL;
+          return nullptr;
         }
       } else {
-      DP("Loading global exec_mode '%s' - symbol missing, using default value "
-          "GENERIC (1)\n", ExecModeName);
-      CUDA_ERR_STRING(err);
+        DP("Loading global exec_mode '%s' - symbol missing, using default "
+           "value GENERIC (1)\n",
+           ExecModeName);
+        CUDA_ERR_STRING(Err);
       }
 
-    KernelsList.push_back(KernelTy(fun, ExecModeVal));
+      KernelsList.emplace_back(Func, ExecModeVal);
 
-    __tgt_offload_entry entry = *e;
-    entry.addr = (void *)&KernelsList.back();
-    DeviceInfo.addOffloadEntry(device_id, entry);
+      __tgt_offload_entry Entry = *E;
+      Entry.addr = &KernelsList.back();
+      addOffloadEntry(DeviceId, Entry);
     }
 
     // send device environment data to the device
     {
-    omptarget_device_environmentTy device_env;
-
-    device_env.debug_level = 0;
+      OMPTargetDeviceEnvironmentTy DeviceEnv;
 
 #ifdef OMPTARGET_DEBUG
-    if (char *envStr = getenv("LIBOMPTARGET_DEVICE_RTL_DEBUG")) {
-      device_env.debug_level = std::stoi(envStr);
-    }
+      if (const char *EnvStr = getenv("LIBOMPTARGET_DEVICE_RTL_DEBUG"))
+        DeviceEnv.DebugLevel = std::stoi(EnvStr);
 #endif
 
-    const char * device_env_Name="omptarget_device_environment";
-    CUdeviceptr device_env_Ptr;
-    size_t cusize;
-
-    err = cuModuleGetGlobal(&device_env_Ptr, &cusize, cumod, device_env_Name);
-
-    if (err == CUDA_SUCCESS) {
-      if ((size_t)cusize != sizeof(device_env)) {
+      const char *DeviceEnvName = "omptarget_device_environment";
+      CUdeviceptr DeviceEnvPtr;
+      size_t CUSize;
+
+      Err = cuModuleGetGlobal(&DeviceEnvPtr, &CUSize, Module, DeviceEnvName);
+      if (Err == CUDA_SUCCESS) {
+        if (CUSize != sizeof(DeviceEnv)) {
           DP("Global device_environment '%s' - size mismatch (%zu != %zu)\n",
-            device_env_Name, cusize, sizeof(int32_t));
-        CUDA_ERR_STRING(err);
-        return NULL;
+             DeviceEnvName, CUSize, sizeof(int32_t));
+          CUDA_ERR_STRING(Err);
+          return nullptr;
         }
 
-      err = cuMemcpyHtoD(device_env_Ptr, &device_env, cusize);
-      if (err != CUDA_SUCCESS) {
+        Err = cuMemcpyHtoD(DeviceEnvPtr, &DeviceEnv, CUSize);
+        // TODO: Improve checkResult function using E->name
+        if (Err != CUDA_SUCCESS) {
           DP("Error when copying data from host to device. Pointers: "
              "host = " DPxMOD ", device = " DPxMOD ", size = %zu\n",
-            DPxPTR(&device_env), DPxPTR(device_env_Ptr), cusize);
-        CUDA_ERR_STRING(err);
-        return NULL;
+             DPxPTR(&DeviceEnv), DPxPTR(DeviceEnvPtr), CUSize);
+          CUDA_ERR_STRING(Err);
+          return nullptr;
         }
 
-      DP("Sending global device environment data %zu bytes\n", (size_t)cusize);
+        DP("Sending global device environment data %zu bytes\n", CUSize);
       } else {
-      DP("Finding global device environment '%s' - symbol missing.\n", device_env_Name);
-      DP("Continue, considering this is a device RTL which does not accept environment setting.\n");
+        DP("Finding global device environment '%s' - symbol missing.\n",
+           DeviceEnvName);
+        DP("Continue, considering this is a device RTL which does not accept "
+           "environment setting.\n");
       }
     }
 
-  return DeviceInfo.getOffloadEntriesTable(device_id);
+    return getOffloadEntriesTable(DeviceId);
   }
 
-void *__tgt_rtl_data_alloc(int32_t device_id, int64_t size, void *hst_ptr) {
-  if (size == 0) {
-    return NULL;
-  }
+  void *dataAlloc(const int DeviceId, const int64_t Size) const {
+    if (Size == 0)
+      return nullptr;
 
-  // Set the context we are using.
-  CUresult err = cuCtxSetCurrent(DeviceInfo.Contexts[device_id]);
-  if (err != CUDA_SUCCESS) {
-    DP("Error while trying to set CUDA current context\n");
-    CUDA_ERR_STRING(err);
-    return NULL;
-  }
+    CUresult Err = cuCtxSetCurrent(DeviceData[DeviceId].Context);
+    if (!checkResult(Err, "Error returned from cuCtxSetCurrent\n"))
+      return nullptr;
 
-  CUdeviceptr ptr;
-  err = cuMemAlloc(&ptr, size);
-  if (err != CUDA_SUCCESS) {
-    DP("Error while trying to allocate %d\n", err);
-    CUDA_ERR_STRING(err);
-    return NULL;
-  }
+    CUdeviceptr DevicePtr;
+    Err = cuMemAlloc(&DevicePtr, Size);
+    if (!checkResult(Err, "Error returned from cuMemAlloc\n"))
+      return nullptr;
 
-  void *vptr = (void *)ptr;
-  return vptr;
+    return (void *)DevicePtr;
   }
 
-int32_t __tgt_rtl_data_submit(int32_t device_id, void *tgt_ptr, void *hst_ptr,
-                              int64_t size) {
-  __tgt_async_info async_info;
-  int32_t rc = __tgt_rtl_data_submit_async(device_id, tgt_ptr, hst_ptr, size,
-                                           &async_info);
-  if (rc != OFFLOAD_SUCCESS)
-    return OFFLOAD_FAIL;
+  int dataSubmit(const int DeviceId, const void *TgtPtr, const void *HstPtr,
+                 const int64_t Size, __tgt_async_info *AsyncInfoPtr) const {
+    assert(AsyncInfoPtr && "AsyncInfoPtr is nullptr");
 
-  return __tgt_rtl_synchronize(device_id, &async_info);
-}
+    CUresult Err = cuCtxSetCurrent(DeviceData[DeviceId].Context);
+    if (!checkResult(Err, "Error returned from cuCtxSetCurrent\n"))
+      return OFFLOAD_FAIL;
 
-int32_t __tgt_rtl_data_submit_async(int32_t device_id, void *tgt_ptr,
-                                    void *hst_ptr, int64_t size,
-                                    __tgt_async_info *async_info_ptr) {
-  assert(async_info_ptr && "async_info_ptr is nullptr");
-  return dataSubmit(device_id, tgt_ptr, hst_ptr, size, async_info_ptr);
-}
+    CUstream Stream = getStream(DeviceId, AsyncInfoPtr);
 
-int32_t __tgt_rtl_data_retrieve(int32_t device_id, void *hst_ptr, void *tgt_ptr,
-                                int64_t size) {
-  __tgt_async_info async_info;
-  int32_t rc = __tgt_rtl_data_retrieve_async(device_id, hst_ptr, tgt_ptr, size,
-                                             &async_info);
-  if (rc != OFFLOAD_SUCCESS)
+    Err = cuMemcpyHtoDAsync((CUdeviceptr)TgtPtr, HstPtr, Size, Stream);
+    if (Err != CUDA_SUCCESS) {
+      DP("Error when copying data from host to device. Pointers: host = " DPxMOD
+         ", device = " DPxMOD ", size = %" PRId64 "\n",
+         DPxPTR(HstPtr), DPxPTR(TgtPtr), Size);
+      CUDA_ERR_STRING(Err);
       return OFFLOAD_FAIL;
-
-  return __tgt_rtl_synchronize(device_id, &async_info);
     }
 
-int32_t __tgt_rtl_data_retrieve_async(int32_t device_id, void *hst_ptr,
-                                      void *tgt_ptr, int64_t size,
-                                      __tgt_async_info *async_info_ptr) {
-  assert(async_info_ptr && "async_info_ptr is nullptr");
-  return dataRetrieve(device_id, hst_ptr, tgt_ptr, size, async_info_ptr);
+    return OFFLOAD_SUCCESS;
   }
 
-int32_t __tgt_rtl_data_delete(int32_t device_id, void *tgt_ptr) {
-  // Set the context we are using.
-  CUresult err = cuCtxSetCurrent(DeviceInfo.Contexts[device_id]);
-  if (err != CUDA_SUCCESS) {
-    DP("Error when setting CUDA context\n");
-    CUDA_ERR_STRING(err);
+  int dataRetrieve(int32_t DeviceId, void *HstPtr, void *TgtPtr, int64_t Size,
+                   __tgt_async_info *AsyncInfoPtr) const {
+    assert(AsyncInfoPtr && "AsyncInfoPtr is nullptr");
+
+    CUresult Err = cuCtxSetCurrent(DeviceData[DeviceId].Context);
+    if (!checkResult(Err, "Error returned from cuCtxSetCurrent\n"))
       return OFFLOAD_FAIL;
-  }
 
-  err = cuMemFree((CUdeviceptr)tgt_ptr);
-  if (err != CUDA_SUCCESS) {
-    DP("Error when freeing CUDA memory\n");
-    CUDA_ERR_STRING(err);
+    CUstream Stream = getStream(DeviceId, AsyncInfoPtr);
+
+    Err = cuMemcpyDtoHAsync(HstPtr, (CUdeviceptr)TgtPtr, Size, Stream);
+    if (Err != CUDA_SUCCESS) {
+      DP("Error when copying data from device to host. Pointers: host = " DPxMOD
+         ", device = " DPxMOD ", size = %" PRId64 "\n",
+         DPxPTR(HstPtr), DPxPTR(TgtPtr), Size);
+      CUDA_ERR_STRING(Err);
       return OFFLOAD_FAIL;
     }
+
     return OFFLOAD_SUCCESS;
   }
 
-int32_t __tgt_rtl_run_target_team_region(int32_t device_id, void *tgt_entry_ptr,
-                                         void **tgt_args,
-                                         ptrdiff_t *tgt_offsets,
-                                         int32_t arg_num, int32_t team_num,
-                                         int32_t thread_limit,
-                                         uint64_t loop_tripcount) {
-  __tgt_async_info async_info;
-  int32_t rc = __tgt_rtl_run_target_team_region_async(
-      device_id, tgt_entry_ptr, tgt_args, tgt_offsets, arg_num, team_num,
-      thread_limit, loop_tripcount, &async_info);
-  if (rc != OFFLOAD_SUCCESS)
+  int dataDelete(const int DeviceId, void *TgtPtr) const {
+    CUresult Err = cuCtxSetCurrent(DeviceData[DeviceId].Context);
+    if (!checkResult(Err, "Error returned from cuCtxSetCurrent\n"))
       return OFFLOAD_FAIL;
 
-  return __tgt_rtl_synchronize(device_id, &async_info);
+    Err = cuMemFree((CUdeviceptr)TgtPtr);
+    if (!checkResult(Err, "Error returned from cuMemFree\n"))
+      return OFFLOAD_FAIL;
+
+    return OFFLOAD_SUCCESS;
   }
 
-int32_t __tgt_rtl_run_target_team_region_async(
-    int32_t device_id, void *tgt_entry_ptr, void **tgt_args,
-    ptrdiff_t *tgt_offsets, int32_t arg_num, int32_t team_num,
-    int32_t thread_limit, uint64_t loop_tripcount,
-    __tgt_async_info *async_info) {
-  // Set the context we are using.
-  CUresult err = cuCtxSetCurrent(DeviceInfo.Contexts[device_id]);
-  if (err != CUDA_SUCCESS) {
-    DP("Error when setting CUDA context\n");
-    CUDA_ERR_STRING(err);
+  int runTargetTeamRegion(const int DeviceId, const void *TgtEntryPtr,
+                          void **TgtArgs, ptrdiff_t *TgtOffsets,
+                          const int ArgNum, const int TeamNum,
+                          const int ThreadLimit,
+                          const unsigned int LoopTripCount,
+                          __tgt_async_info *AsyncInfo) const {
+    CUresult Err = cuCtxSetCurrent(DeviceData[DeviceId].Context);
+    if (!checkResult(Err, "Error returned from cuCtxSetCurrent\n"))
       return OFFLOAD_FAIL;
-  }
 
     // All args are references.
-  std::vector<void *> args(arg_num);
-  std::vector<void *> ptrs(arg_num);
+    std::vector<void *> Args(ArgNum);
+    std::vector<void *> Ptrs(ArgNum);
 
-  for (int32_t i = 0; i < arg_num; ++i) {
-    ptrs[i] = (void *)((intptr_t)tgt_args[i] + tgt_offsets[i]);
-    args[i] = &ptrs[i];
+    for (int I = 0; I < ArgNum; ++I) {
+      Ptrs[I] = (void *)((intptr_t)TgtArgs[I] + TgtOffsets[I]);
+      Args[I] = &Ptrs[I];
     }
 
-  KernelTy *KernelInfo = (KernelTy *)tgt_entry_ptr;
-
-  int cudaThreadsPerBlock;
+    const KernelTy *KernelInfo =
+        reinterpret_cast<const KernelTy *>(TgtEntryPtr);
 
-  if (thread_limit > 0) {
-    cudaThreadsPerBlock = thread_limit;
-    DP("Setting CUDA threads per block to requested %d\n", thread_limit);
+    unsigned int CudaThreadsPerBlock;
+    if (ThreadLimit > 0) {
+      DP("Setting CUDA threads per block to requested %d\n", ThreadLimit);
+      CudaThreadsPerBlock = ThreadLimit;
       // Add master warp if necessary
       if (KernelInfo->ExecutionMode == GENERIC) {
-      cudaThreadsPerBlock += DeviceInfo.WarpSize[device_id];
-      DP("Adding master warp: +%d threads\n", DeviceInfo.WarpSize[device_id]);
+        DP("Adding master warp: +%d threads\n", DeviceData[DeviceId].WarpSize);
+        CudaThreadsPerBlock += DeviceData[DeviceId].WarpSize;
       }
     } else {
-    cudaThreadsPerBlock = DeviceInfo.NumThreads[device_id];
       DP("Setting CUDA threads per block to default %d\n",
-        DeviceInfo.NumThreads[device_id]);
+         DeviceData[DeviceId].NumThreads);
+      CudaThreadsPerBlock = DeviceData[DeviceId].NumThreads;
     }
 
-  if (cudaThreadsPerBlock > DeviceInfo.ThreadsPerBlock[device_id]) {
-    cudaThreadsPerBlock = DeviceInfo.ThreadsPerBlock[device_id];
+    if (CudaThreadsPerBlock > DeviceData[DeviceId].ThreadsPerBlock) {
       DP("Threads per block capped at device limit %d\n",
-        DeviceInfo.ThreadsPerBlock[device_id]);
+         DeviceData[DeviceId].ThreadsPerBlock);
+      CudaThreadsPerBlock = DeviceData[DeviceId].ThreadsPerBlock;
     }
 
-  int kernel_limit;
-  err = cuFuncGetAttribute(&kernel_limit,
-      CU_FUNC_ATTRIBUTE_MAX_THREADS_PER_BLOCK, KernelInfo->Func);
-  if (err == CUDA_SUCCESS) {
-    if (kernel_limit < cudaThreadsPerBlock) {
-      cudaThreadsPerBlock = kernel_limit;
-      DP("Threads per block capped at kernel limit %d\n", kernel_limit);
-    }
-  }
-
-  int cudaBlocksPerGrid;
-  if (team_num <= 0) {
-    if (loop_tripcount > 0 && DeviceInfo.EnvNumTeams < 0) {
+    int KernelLimit;
+    Err = cuFuncGetAttribute(&KernelLimit,
+                             CU_FUNC_ATTRIBUTE_MAX_THREADS_PER_BLOCK,
+                             KernelInfo->Func);
+    if (Err == CUDA_SUCCESS && KernelLimit < CudaThreadsPerBlock) {
+      DP("Threads per block capped at kernel limit %d\n", KernelLimit);
+      CudaThreadsPerBlock = KernelLimit;
+    }
+
+    unsigned int CudaBlocksPerGrid;
+    if (TeamNum <= 0) {
+      if (LoopTripCount > 0 && EnvNumTeams < 0) {
         if (KernelInfo->ExecutionMode == SPMD) {
-        // We have a combined construct, i.e. `target teams distribute parallel
-        // for [simd]`. We launch so many teams so that each thread will
-        // execute one iteration of the loop.
-        // round up to the nearest integer
-        cudaBlocksPerGrid = ((loop_tripcount - 1) / cudaThreadsPerBlock) + 1;
+          // We have a combined construct, i.e. `target teams distribute
+          // parallel for [simd]`. We launch so many teams so that each thread
+          // will execute one iteration of the loop. round up to the nearest
+          // integer
+          CudaBlocksPerGrid = ((LoopTripCount - 1) / CudaThreadsPerBlock) + 1;
         } else {
           // If we reach this point, then we have a non-combined construct, i.e.
           // `teams distribute` with a nested `parallel for` and each team is
           // assigned one iteration of the `distribute` loop. E.g.:
           //
           // #pragma omp target teams distribute
           // for(...loop_tripcount...) {
           //   #pragma omp parallel for
           //   for(...) {}
           // }
           //
           // Threads within a team will execute the iterations of the `parallel`
           // loop.
-        cudaBlocksPerGrid = loop_tripcount;
+          CudaBlocksPerGrid = LoopTripCount;
         }
-      DP("Using %d teams due to loop trip count %" PRIu64 " and number of "
-          "threads per block %d\n", cudaBlocksPerGrid, loop_tripcount,
-          cudaThreadsPerBlock);
+        DP("Using %d teams due to loop trip count %" PRIu64
+           " and number of threads per block %d\n",
+           CudaBlocksPerGrid, LoopTripCount, CudaThreadsPerBlock);
       } else {
-      cudaBlocksPerGrid = DeviceInfo.NumTeams[device_id];
-      DP("Using default number of teams %d\n", DeviceInfo.NumTeams[device_id]);
+        DP("Using default number of teams %d\n", DeviceData[DeviceId].NumTeams);
+        CudaBlocksPerGrid = DeviceData[DeviceId].NumTeams;
       }
-  } else if (team_num > DeviceInfo.BlocksPerGrid[device_id]) {
-    cudaBlocksPerGrid = DeviceInfo.BlocksPerGrid[device_id];
+    } else if (TeamNum > DeviceData[DeviceId].BlocksPerGrid) {
       DP("Capping number of teams to team limit %d\n",
-        DeviceInfo.BlocksPerGrid[device_id]);
+         DeviceData[DeviceId].BlocksPerGrid);
+      CudaBlocksPerGrid = DeviceData[DeviceId].BlocksPerGrid;
     } else {
-    cudaBlocksPerGrid = team_num;
-    DP("Using requested number of teams %d\n", team_num);
+      DP("Using requested number of teams %d\n", TeamNum);
+      CudaBlocksPerGrid = TeamNum;
     }
 
     // Run on the device.
-  DP("Launch kernel with %d blocks and %d threads\n", cudaBlocksPerGrid,
-     cudaThreadsPerBlock);
+    DP("Launch kernel with %d blocks and %d threads\n", CudaBlocksPerGrid,
+       CudaThreadsPerBlock);
 
-  CUstream Stream = getStream(device_id, async_info);
-  err = cuLaunchKernel(KernelInfo->Func, cudaBlocksPerGrid, 1, 1,
-                       cudaThreadsPerBlock, 1, 1, 0 /*bytes of shared memory*/,
-                       Stream, &args[0], 0);
-  if (err != CUDA_SUCCESS) {
-    DP("Device kernel launch failed!\n");
-    CUDA_ERR_STRING(err);
+    CUstream Stream = getStream(DeviceId, AsyncInfo);
+    Err =
+        cuLaunchKernel(KernelInfo->Func, CudaBlocksPerGrid, 1, 1,
+                       CudaThreadsPerBlock, 1, 1, 0, Stream, &Args[0], nullptr);
+    if (!checkResult(Err, "Error returned from cuLaunchKernel\n"))
       return OFFLOAD_FAIL;
-  }
 
     DP("Launch of entry point at " DPxMOD " successful!\n",
-     DPxPTR(tgt_entry_ptr));
+       DPxPTR(TgtEntryPtr));
+
+    return OFFLOAD_SUCCESS;
+  }
+
+  int synchronize(const int DeviceId, __tgt_async_info *AsyncInfoPtr) const {
+    CUstream Stream = reinterpret_cast<CUstream>(AsyncInfoPtr->Queue);
+    CUresult Err = cuStreamSynchronize(Stream);
+    if (Err != CUDA_SUCCESS) {
+      DP("Error when synchronizing stream. stream = " DPxMOD
+         ", async info ptr = " DPxMOD "\n",
+         DPxPTR(Stream), DPxPTR(AsyncInfoPtr));
+      CUDA_ERR_STRING(Err);
+      return OFFLOAD_FAIL;
+    }
+
+    // Once the stream is synchronized, return it to stream pool and reset
+    // async_info. This is to make sure the synchronization only works for its
+    // own tasks.
+    StreamManager->returnStream(
+        DeviceId, reinterpret_cast<CUstream>(AsyncInfoPtr->Queue));
+    AsyncInfoPtr->Queue = nullptr;
 
     return OFFLOAD_SUCCESS;
   }
+};
+
+DeviceRTLTy DeviceRTL;
+} // namespace
+
+// Exposed library API function
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+int32_t __tgt_rtl_is_valid_binary(__tgt_device_image *image) {
+  return elf_check_machine(image, 190); // EM_CUDA = 190.
+}
+
+int32_t __tgt_rtl_number_of_devices() { return DeviceRTL.getNumOfDevices(); }
+
+int64_t __tgt_rtl_init_requires(int64_t RequiresFlags) {
+  DP("Init requires flags to %ld\n", RequiresFlags);
+  DeviceRTL.setRequiresFlag(RequiresFlags);
+  return RequiresFlags;
+}
+
+int32_t __tgt_rtl_init_device(int32_t device_id) {
+  assert(DeviceRTL.isValidDeviceId(device_id) && "device_id is invalid");
+
+  return DeviceRTL.initDevice(device_id);
+}
+
+__tgt_target_table *__tgt_rtl_load_binary(int32_t device_id,
+                                          __tgt_device_image *image) {
+  assert(DeviceRTL.isValidDeviceId(device_id) && "device_id is invalid");
+
+  return DeviceRTL.loadBinary(device_id, image);
+}
+
+void *__tgt_rtl_data_alloc(int32_t device_id, int64_t size, void *) {
+  assert(DeviceRTL.isValidDeviceId(device_id) && "device_id is invalid");
+
+  return DeviceRTL.dataAlloc(device_id, size);
+}
+
+int32_t __tgt_rtl_data_submit(int32_t device_id, void *tgt_ptr, void *hst_ptr,
+                              int64_t size) {
+  assert(DeviceRTL.isValidDeviceId(device_id) && "device_id is invalid");
+
+  __tgt_async_info async_info;
+  const int32_t rc = __tgt_rtl_data_submit_async(device_id, tgt_ptr, hst_ptr,
+                                                 size, &async_info);
+  if (rc != OFFLOAD_SUCCESS)
+    return OFFLOAD_FAIL;
+
+  return __tgt_rtl_synchronize(device_id, &async_info);
+}
+
+int32_t __tgt_rtl_data_submit_async(int32_t device_id, void *tgt_ptr,
+                                    void *hst_ptr, int64_t size,
+                                    __tgt_async_info *async_info_ptr) {
+  assert(DeviceRTL.isValidDeviceId(device_id) && "device_id is invalid");
+  assert(async_info_ptr && "async_info_ptr is nullptr");
+
+  return DeviceRTL.dataSubmit(device_id, tgt_ptr, hst_ptr, size,
+                              async_info_ptr);
+}
+
+int32_t __tgt_rtl_data_retrieve(int32_t device_id, void *hst_ptr, void *tgt_ptr,
+                                int64_t size) {
+  assert(DeviceRTL.isValidDeviceId(device_id) && "device_id is invalid");
+
+  __tgt_async_info async_info;
+  const int32_t rc = __tgt_rtl_data_retrieve_async(device_id, hst_ptr, tgt_ptr,
+                                                   size, &async_info);
+  if (rc != OFFLOAD_SUCCESS)
+    return OFFLOAD_FAIL;
+
+  return __tgt_rtl_synchronize(device_id, &async_info);
+}
+
+int32_t __tgt_rtl_data_retrieve_async(int32_t device_id, void *hst_ptr,
+                                      void *tgt_ptr, int64_t size,
+                                      __tgt_async_info *async_info_ptr) {
+  assert(DeviceRTL.isValidDeviceId(device_id) && "device_id is invalid");
+  assert(async_info_ptr && "async_info_ptr is nullptr");
+
+  return DeviceRTL.dataRetrieve(device_id, hst_ptr, tgt_ptr, size,
+                                async_info_ptr);
+}
+
+int32_t __tgt_rtl_data_delete(int32_t device_id, void *tgt_ptr) {
+  assert(DeviceRTL.isValidDeviceId(device_id) && "device_id is invalid");
+
+  return DeviceRTL.dataDelete(device_id, tgt_ptr);
+}
+
+int32_t __tgt_rtl_run_target_team_region(int32_t device_id, void *tgt_entry_ptr,
+                                         void **tgt_args,
+                                         ptrdiff_t *tgt_offsets,
+                                         int32_t arg_num, int32_t team_num,
+                                         int32_t thread_limit,
+                                         uint64_t loop_tripcount) {
+  assert(DeviceRTL.isValidDeviceId(device_id) && "device_id is invalid");
+
+  __tgt_async_info async_info;
+  const int32_t rc = __tgt_rtl_run_target_team_region_async(
+      device_id, tgt_entry_ptr, tgt_args, tgt_offsets, arg_num, team_num,
+      thread_limit, loop_tripcount, &async_info);
+  if (rc != OFFLOAD_SUCCESS)
+    return OFFLOAD_FAIL;
+
+  return __tgt_rtl_synchronize(device_id, &async_info);
+}
+
+int32_t __tgt_rtl_run_target_team_region_async(
+    int32_t device_id, void *tgt_entry_ptr, void **tgt_args,
+    ptrdiff_t *tgt_offsets, int32_t arg_num, int32_t team_num,
+    int32_t thread_limit, uint64_t loop_tripcount,
+    __tgt_async_info *async_info_ptr) {
+  assert(DeviceRTL.isValidDeviceId(device_id) && "device_id is invalid");
+
+  return DeviceRTL.runTargetTeamRegion(
+      device_id, tgt_entry_ptr, tgt_args, tgt_offsets, arg_num, team_num,
+      thread_limit, loop_tripcount, async_info_ptr);
+}
 
 int32_t __tgt_rtl_run_target_region(int32_t device_id, void *tgt_entry_ptr,
                                     void **tgt_args, ptrdiff_t *tgt_offsets,
                                     int32_t arg_num) {
+  assert(DeviceRTL.isValidDeviceId(device_id) && "device_id is invalid");
+
   __tgt_async_info async_info;
-  int32_t rc = __tgt_rtl_run_target_region_async(
+  const int32_t rc = __tgt_rtl_run_target_region_async(
       device_id, tgt_entry_ptr, tgt_args, tgt_offsets, arg_num, &async_info);
   if (rc != OFFLOAD_SUCCESS)
     return OFFLOAD_FAIL;
 
   return __tgt_rtl_synchronize(device_id, &async_info);
 }
 
 int32_t __tgt_rtl_run_target_region_async(int32_t device_id,
                                           void *tgt_entry_ptr, void **tgt_args,
                                           ptrdiff_t *tgt_offsets,
                                           int32_t arg_num,
-                                          __tgt_async_info *async_info) {
-  // use one team and the default number of threads.
-  const int32_t team_num = 1;
-  const int32_t thread_limit = 0;
-  return __tgt_rtl_run_target_team_region_async(
-      device_id, tgt_entry_ptr, tgt_args, tgt_offsets, arg_num, team_num,
-      thread_limit, 0, async_info);
-}
-
-int32_t __tgt_rtl_synchronize(int32_t device_id, __tgt_async_info *async_info) {
-  assert(async_info && "async_info is nullptr");
-  assert(async_info->Queue && "async_info->Queue is nullptr");
+                                          __tgt_async_info *async_info_ptr) {
+  assert(DeviceRTL.isValidDeviceId(device_id) && "device_id is invalid");
 
-  CUstream Stream = reinterpret_cast<CUstream>(async_info->Queue);
-  CUresult Err = cuStreamSynchronize(Stream);
-  if (Err != CUDA_SUCCESS) {
-    DP("Error when synchronizing stream. stream = " DPxMOD
-       ", async info ptr = " DPxMOD "\n",
-       DPxPTR(Stream), DPxPTR(async_info));
-    CUDA_ERR_STRING(Err);
-    return OFFLOAD_FAIL;
-  }
+  return __tgt_rtl_run_target_team_region_async(device_id, tgt_entry_ptr,
+                                                tgt_args, tgt_offsets, arg_num,
+                                                1, 1, 0, async_info_ptr);
 
-  // Once the stream is synchronized, return it to stream pool and reset
-  // async_info. This is to make sure the synchronization only works for its own
-  // tasks.
-  DeviceInfo.returnStream(device_id, async_info);
+int32_t __tgt_rtl_synchronize(int32_t device_id,
+                              __tgt_async_info *async_info_ptr) {
+  assert(DeviceRTL.isValidDeviceId(device_id) && "device_id is invalid");
+  assert(async_info_ptr && "async_info_ptr is nullptr");
+  assert(async_info_ptr->Queue && "async_info_ptr->Queue is nullptr");
 
-  return OFFLOAD_SUCCESS;
+  return DeviceRTL.synchronize(device_id, async_info_ptr);
 }
 
 #ifdef __cplusplus
 }
 #endif