Here is an interesting thread discussing the memory issue for PyTorch (which I think is also relevant to PETSc):
https://github.com/pytorch/pytorch/issues/12873 The memory overhead (for both CPU and GPU) of PyTorch is getting worse and worse as it evolves. A conjecture is that the CUDA kernels in the library are responsible for this. But the overhead for Tensorflow2 is just around 300MB (compare to 1.5GB for PyTorch). According to the discussion, there has not been a good way to decrease the memory overhead for PyTorch yet. Someone noticed that “removing half of the CUDA kernels can reduce the memory usage by half." Hong On Jan 7, 2022, at 9:23 PM, Barry Smith <[email protected]> wrote: Doesn't Nvidia supply a "valgrind" like tool that will allow tracking memory usage? I'm pretty sure I've seen one; it should be able to show memory usage as a function of time so you can see where the memory is being allocated Barry On Jan 7, 2022, at 1:56 PM, Jacob Faibussowitsch <[email protected]<mailto:[email protected]>> wrote: it seems that PETSc consumes 0.73GB CUDA memory and this overhead persists across the entire running time of an application. cupm_initialize contributes 0.36GB out of 0.73GB. If I had to guess this may be the latent overhead of CUDA streams and events, but even then 360 MB seems ludicrous. CUDA maintains a persistent pool of streams that is not freed until cudaDeviceReset() is called. Maybe they initialize this pool immediately on start-up of the context? AFAIK there is no way to disable or modify this behavior. Best regards, Jacob Faibussowitsch (Jacob Fai - booss - oh - vitch) On Jan 7, 2022, at 13:23, Zhang, Hong <[email protected]<mailto:[email protected]>> wrote: Apart from the 1.2GB caused by importing torch, it seems that PETSc consumes 0.73GB CUDA memory and this overhead persists across the entire running time of an application. cupm_initialize contributes 0.36GB out of 0.73GB. It is still unclear what takes the remaining 0.37GB. The torch issue is really a mystery. If I import torch only and do some tensor operations on GPU, it consumes only 0.004GB CUDA memory. On Jan 7, 2022, at 11:54 AM, Zhang, Hong via petsc-dev <[email protected]<mailto:[email protected]>> wrote: 1. Commenting out ierr = __initialize(dctx->device->deviceId,dci);CHKERRQ(ierr); in device/impls/cupm/cupmcontext.hpp:L199 CUDA memory: 1.575GB CUDA memory without importing torch: 0.370GB This has the same effect as commenting out L437-L440 in interface/device.cxx 2. Comment out these two: . src/sys/objects/device/impls/cupm/cupmdevice.cxx:327 [ierr = _devices[_defaultDevice]->configure();CHKERRQ(ierr);] . src/sys/objects/device/impls/cupm/cupmdevice.cxx:326 [ierr = _devices[_defaultDevice]->initialize();CHKERRQ(ierr);] CUDA memory: 1.936GB CUDA memory without importing torch: 0.730GB On Jan 7, 2022, at 11:21 AM, Jacob Faibussowitsch <[email protected]<mailto:[email protected]>> wrote: They had no influence to the memory usage. ??????????????????????????????????????????????????????????????????????? Comment out the ierr = _devices[id]->initialize();CHKERRQ(ierr); on line 360 in cupmdevice.cxx as well. Best regards, Jacob Faibussowitsch (Jacob Fai - booss - oh - vitch) On Jan 7, 2022, at 12:18, Zhang, Hong <[email protected]<mailto:[email protected]>> wrote: I have tried all of these. They had no influence to the memory usage. On Jan 7, 2022, at 11:15 AM, Jacob Faibussowitsch <[email protected]<mailto:[email protected]>> wrote: Initializing cutlass and cusolver does not affect the memory usage. I did the following to turn them off: Ok next things to try out in order: 1. src/sys/objects/device/impls/cupm/cupmcontext.hpp:178 [PetscFunctionBegin;] Put a PetscFunctionReturn(0); right after this 2. src/sys/objects/device/impls/cupm/cupmdevice.cxx:327 [ierr = _devices[_defaultDevice]->configure();CHKERRQ(ierr);] Comment this out 3. src/sys/objects/device/impls/cupm/cupmdevice.cxx:326 [ierr = _devices[_defaultDevice]->initialize();CHKERRQ(ierr);] Comment this out Best regards, Jacob Faibussowitsch (Jacob Fai - booss - oh - vitch) On Jan 7, 2022, at 12:02, Zhang, Hong <[email protected]<mailto:[email protected]>> wrote: Initializing cutlass and cusolver does not affect the memory usage. I did the following to turn them off: diff --git a/src/sys/objects/device/impls/cupm/cupmcontext.hpp b/src/sys/objects/device/impls/cupm/cupmcontext.hpp index 51fed809e4d..9a5f068323a 100644 --- a/src/sys/objects/device/impls/cupm/cupmcontext.hpp +++ b/src/sys/objects/device/impls/cupm/cupmcontext.hpp @@ -199,7 +199,7 @@ inline PetscErrorCode CUPMContext<T>::setUp(PetscDeviceContext dctx) noexcept #if PetscDefined(USE_DEBUG) dci->timerInUse = PETSC_FALSE; #endif - ierr = __initialize(dctx->device->deviceId,dci);CHKERRQ(ierr); + //ierr = __initialize(dctx->device->deviceId,dci);CHKERRQ(ierr); PetscFunctionReturn(0); } On Jan 7, 2022, at 10:53 AM, Barry Smith <[email protected]<mailto:[email protected]>> wrote: I don't think this is right. We want the device initialized by PETSc , we just don't want the cublas and cusolve stuff initialized. In order to see how much memory initializing the blas and solvers takes. So I think you need to comment things in cupminterface.hpp like cublasCreate and cusolverDnCreate. Urgh, I hate C++ where huge chunks of real code are in header files. On Jan 7, 2022, at 11:34 AM, Jacob Faibussowitsch <[email protected]<mailto:[email protected]>> wrote: Hit send too early… If you don’t want to comment out, you can also run with "-device_enable lazy" option. Normally this is the default behavior but if -log_view or -log_summary is provided this defaults to “-device_enable eager”. See src/sys/objects/device/interface/device.cxx:398 Best regards, Jacob Faibussowitsch (Jacob Fai - booss - oh - vitch) On Jan 7, 2022, at 11:29, Jacob Faibussowitsch <[email protected]<mailto:[email protected]>> wrote: You need to go into the PetscInitialize() routine find where it loads the cublas and cusolve and comment out those lines then run with -log_view Comment out #if (PetscDefined(HAVE_CUDA) || PetscDefined(HAVE_HIP) || PetscDefined(HAVE_SYCL)) ierr = PetscDeviceInitializeFromOptions_Internal(PETSC_COMM_WORLD);CHKERRQ(ierr); #endif At src/sys/objects/pinit.c:956 Best regards, Jacob Faibussowitsch (Jacob Fai - booss - oh - vitch) On Jan 7, 2022, at 11:24, Barry Smith <[email protected]<mailto:[email protected]>> wrote: Without log_view it does not load any cuBLAS/cuSolve immediately with -log_view it loads all that stuff at startup. You need to go into the PetscInitialize() routine find where it loads the cublas and cusolve and comment out those lines then run with -log_view On Jan 7, 2022, at 11:14 AM, Zhang, Hong via petsc-dev <[email protected]<mailto:[email protected]>> wrote: When PETSc is initialized, it takes about 2GB CUDA memory. This is way too much for doing nothing. A test script is attached to reproduce the issue. If I remove the first line "import torch", PETSc consumes about 0.73GB, which is still significant. Does anyone have any idea about this behavior? Thanks, Hong hongzhang@gpu02:/gpfs/jlse-fs0/users/hongzhang/Projects/pnode/examples (caidao22/update-examples)$ python3 test.py CUDA memory before PETSc 0.000GB CUDA memory after PETSc 0.004GB hongzhang@gpu02:/gpfs/jlse-fs0/users/hongzhang/Projects/pnode/examples (caidao22/update-examples)$ python3 test.py -log_view :0.txt CUDA memory before PETSc 0.000GB CUDA memory after PETSc 1.936GB import torch import sys import os import nvidia_smi nvidia_smi.nvmlInit() handle = nvidia_smi.nvmlDeviceGetHandleByIndex(0) info = nvidia_smi.nvmlDeviceGetMemoryInfo(handle) print('CUDA memory before PETSc %.3fGB' % (info.used/1e9)) petsc4py_path = os.path.join(os.environ['PETSC_DIR'],os.environ['PETSC_ARCH'],'lib') sys.path.append(petsc4py_path) import petsc4py petsc4py.init(sys.argv) handle = nvidia_smi.nvmlDeviceGetHandleByIndex(0) info = nvidia_smi.nvmlDeviceGetMemoryInfo(handle) print('CUDA memory after PETSc %.3fGB' % (info.used/1e9))
