fb32977ac7
Summary: The device allocator on NVPTX architectures is enqueued to a stream that the kernel is potentially executing on. This can lead to deadlocks as the kernel will not proceed until the allocation is complete and the allocation will not proceed until the kernel is complete. CUDA 11.2 introduced async allocations that we can manually place on separate streams to combat this. This patch makes a new allocation type that's guaranteed to be non-blocking so it will actually make progress, only Nvidia needs to care about this as the others are not blocking in this way by default. I had originally tried to make the `alloc` and `free` methods take a `__tgt_async_info`. However, I observed that with the large volume of streams being created by a parallel test it quickly locked up the system as presumably too many streams were being created. This implementation not just creates a new stream and immediately destroys it. This obviously isn't very fast, but it at least gets the cases to stop deadlocking for now.
171 lines
4.5 KiB
C++
171 lines
4.5 KiB
C++
//===--- cuda/dynamic_cuda/cuda.pp ------------------------------- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// Implement subset of cuda api by calling into cuda library via dlopen
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// Does the dlopen/dlsym calls as part of the call to cuInit
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/DynamicLibrary.h"
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#include "Shared/Debug.h"
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#include "DLWrap.h"
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#include "cuda.h"
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#include <memory>
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#include <string>
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#include <unordered_map>
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DLWRAP_INITIALIZE()
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DLWRAP_INTERNAL(cuInit, 1)
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DLWRAP(cuCtxGetDevice, 1)
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DLWRAP(cuDeviceGet, 2)
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DLWRAP(cuDeviceGetAttribute, 3)
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DLWRAP(cuDeviceGetCount, 1)
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DLWRAP(cuFuncGetAttribute, 3)
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// Device info
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DLWRAP(cuDeviceGetName, 3)
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DLWRAP(cuDeviceTotalMem, 2)
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DLWRAP(cuDriverGetVersion, 1)
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DLWRAP(cuGetErrorString, 2)
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DLWRAP(cuLaunchKernel, 11)
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DLWRAP(cuMemAlloc, 2)
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DLWRAP(cuMemAllocHost, 2)
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DLWRAP(cuMemAllocManaged, 3)
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DLWRAP(cuMemAllocAsync, 3)
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DLWRAP(cuMemcpyDtoDAsync, 4)
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DLWRAP(cuMemcpyDtoH, 3)
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DLWRAP(cuMemcpyDtoHAsync, 4)
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DLWRAP(cuMemcpyHtoD, 3)
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DLWRAP(cuMemcpyHtoDAsync, 4)
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DLWRAP(cuMemFree, 1)
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DLWRAP(cuMemFreeHost, 1)
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DLWRAP(cuMemFreeAsync, 2)
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DLWRAP(cuModuleGetFunction, 3)
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DLWRAP(cuModuleGetGlobal, 4)
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DLWRAP(cuModuleUnload, 1)
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DLWRAP(cuStreamCreate, 2)
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DLWRAP(cuStreamDestroy, 1)
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DLWRAP(cuStreamSynchronize, 1)
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DLWRAP(cuStreamQuery, 1)
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DLWRAP(cuCtxSetCurrent, 1)
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DLWRAP(cuDevicePrimaryCtxRelease, 1)
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DLWRAP(cuDevicePrimaryCtxGetState, 3)
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DLWRAP(cuDevicePrimaryCtxSetFlags, 2)
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DLWRAP(cuDevicePrimaryCtxRetain, 2)
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DLWRAP(cuModuleLoadDataEx, 5)
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DLWRAP(cuDeviceCanAccessPeer, 3)
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DLWRAP(cuCtxEnablePeerAccess, 2)
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DLWRAP(cuMemcpyPeerAsync, 6)
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DLWRAP(cuCtxGetLimit, 2)
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DLWRAP(cuCtxSetLimit, 2)
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DLWRAP(cuEventCreate, 2)
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DLWRAP(cuEventRecord, 2)
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DLWRAP(cuStreamWaitEvent, 3)
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DLWRAP(cuEventSynchronize, 1)
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DLWRAP(cuEventDestroy, 1)
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DLWRAP_FINALIZE()
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DLWRAP(cuMemUnmap, 2)
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DLWRAP(cuMemRelease, 1)
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DLWRAP(cuMemAddressFree, 2)
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DLWRAP(cuMemGetInfo, 2)
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DLWRAP(cuMemAddressReserve, 5)
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DLWRAP(cuMemMap, 5)
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DLWRAP(cuMemCreate, 4)
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DLWRAP(cuMemSetAccess, 4)
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DLWRAP(cuMemGetAllocationGranularity, 3)
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#ifndef DYNAMIC_CUDA_PATH
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#define DYNAMIC_CUDA_PATH "libcuda.so"
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#endif
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#ifndef TARGET_NAME
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#define TARGET_NAME CUDA
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#endif
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#ifndef DEBUG_PREFIX
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#define DEBUG_PREFIX "Target " GETNAME(TARGET_NAME) " RTL"
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#endif
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static bool checkForCUDA() {
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// return true if dlopen succeeded and all functions found
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// Prefer _v2 versions of functions if found in the library
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std::unordered_map<std::string, const char *> TryFirst = {
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{"cuMemAlloc", "cuMemAlloc_v2"},
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{"cuMemFree", "cuMemFree_v2"},
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{"cuMemcpyDtoH", "cuMemcpyDtoH_v2"},
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{"cuMemcpyHtoD", "cuMemcpyHtoD_v2"},
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{"cuStreamDestroy", "cuStreamDestroy_v2"},
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{"cuModuleGetGlobal", "cuModuleGetGlobal_v2"},
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{"cuMemcpyDtoHAsync", "cuMemcpyDtoHAsync_v2"},
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{"cuMemcpyDtoDAsync", "cuMemcpyDtoDAsync_v2"},
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{"cuMemcpyHtoDAsync", "cuMemcpyHtoDAsync_v2"},
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{"cuDevicePrimaryCtxRelease", "cuDevicePrimaryCtxRelease_v2"},
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{"cuDevicePrimaryCtxSetFlags", "cuDevicePrimaryCtxSetFlags_v2"},
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};
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const char *CudaLib = DYNAMIC_CUDA_PATH;
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std::string ErrMsg;
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auto DynlibHandle = std::make_unique<llvm::sys::DynamicLibrary>(
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llvm::sys::DynamicLibrary::getPermanentLibrary(CudaLib, &ErrMsg));
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if (!DynlibHandle->isValid()) {
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DP("Unable to load library '%s': %s!\n", CudaLib, ErrMsg.c_str());
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return false;
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}
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for (size_t I = 0; I < dlwrap::size(); I++) {
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const char *Sym = dlwrap::symbol(I);
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auto It = TryFirst.find(Sym);
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if (It != TryFirst.end()) {
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const char *First = It->second;
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void *P = DynlibHandle->getAddressOfSymbol(First);
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if (P) {
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DP("Implementing %s with dlsym(%s) -> %p\n", Sym, First, P);
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*dlwrap::pointer(I) = P;
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continue;
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}
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}
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void *P = DynlibHandle->getAddressOfSymbol(Sym);
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if (P == nullptr) {
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DP("Unable to find '%s' in '%s'!\n", Sym, CudaLib);
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return false;
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}
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DP("Implementing %s with dlsym(%s) -> %p\n", Sym, Sym, P);
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*dlwrap::pointer(I) = P;
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}
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return true;
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}
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CUresult cuInit(unsigned X) {
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// Note: Called exactly once from cuda rtl.cpp in a global constructor so
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// does not need to handle being called repeatedly or concurrently
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if (!checkForCUDA()) {
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return CUDA_ERROR_INVALID_HANDLE;
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}
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return dlwrap_cuInit(X);
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}
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