[petsc-dev] MatPinToCPU
Karl Rupp
rupp at iue.tuwien.ac.at
Sun Jul 28 13:33:58 CDT 2019
Hi Mark,
feel free to submit a fresh pull request now. I looked at your latest
commit in the repository in order to cherry-pick it, but it looked like
it had a few other bits in it as well.
Best regards,
Karli
On 7/28/19 6:27 PM, Mark Adams via petsc-dev wrote:
> This is looking good. I'm not seeing the numerical problems, but I've
> just hid them by avoiding the GPU on coarse grids.
>
> Should I submit a pull request now or test more or wait for Karl?
>
> On Sat, Jul 27, 2019 at 7:37 PM Mark Adams <mfadams at lbl.gov
> <mailto:mfadams at lbl.gov>> wrote:
>
> Barry, I fixed CUDA to pin to CPUs correctly for GAMG at least.
> There are some hacks here that we can work on.
>
> I will start testing it tomorrow, but I am pretty sure that I have
> not regressed. I am hoping that this will fix the numerical
> problems, which seem to be associated with empty processors.
>
> I did need to touch code outside of GAMG and CUDA. It might be nice
> to test this in a next.
>
> GAMG now puts all reduced processorg grids on the CPU. This could be
> looked at in the future.
>
>
> On Sat, Jul 27, 2019 at 1:00 PM Smith, Barry F. <bsmith at mcs.anl.gov
> <mailto:bsmith at mcs.anl.gov>> wrote:
>
>
>
> > On Jul 27, 2019, at 11:53 AM, Mark Adams <mfadams at lbl.gov
> <mailto:mfadams at lbl.gov>> wrote:
> >
> >
> > On Sat, Jul 27, 2019 at 11:39 AM Smith, Barry F.
> <bsmith at mcs.anl.gov <mailto:bsmith at mcs.anl.gov>> wrote:
> >
> > Good catch. Thanks. Maybe the SeqCUDA has the same problem?
> >
> > THis is done (I may have done it).
> >
> > Now it seems to me that when you call VecPinToCPU you are
> setting up and don't have data, so this copy does not seem
> necessary. Maybe remove the copy here:
> >
> > PetscErrorCode VecPinToCPU_MPICUDA(Vec V,PetscBool pin)
> > {
> > PetscErrorCode ierr;
> >
> > PetscFunctionBegin;
> > V->pinnedtocpu = pin;
> > if (pin) {
> > ierr = VecCUDACopyFromGPU(V);CHKERRQ(ierr); ????
>
> The copy from GPU should actually only do anything if the
> GPU already has data and PETSC_OFFLOAD_GPU. If the GPU does not
> have data
> the copy doesn't do anything. When one calls VecPinToCPU() one
> doesn't know where the data is so the call must be made, but it
> may do nothing
>
> Note that VecCUDACopyFromGPU() calls
> VecCUDAAllocateCheckHost() not VecCUDAAllocateCheck() so the GPU
> will not allocate space,
> VecCUDAAllocateCheck() is called from VecCUDACopyToGPU().
>
> Yes, perhaps the naming could be more consistent:
>
> 1) in one place it is Host in an other place it is nothing
> 2) some places it is Host, Device, some places GPU,CPU
>
> Perhaps Karl can make these all consistent and simpler in
> his refactorization
>
>
> Barry
>
>
> >
> > or
> >
> > Not allocate the GPU if it is pinned by added in a check here:
> >
> > PetscErrorCode VecCUDAAllocateCheck(Vec v)
> > {
> > PetscErrorCode ierr;
> > cudaError_t err;
> > cudaStream_t stream;
> > Vec_CUDA *veccuda;
> >
> > PetscFunctionBegin;
> > if (!v->spptr) {
> > ierr = PetscMalloc(sizeof(Vec_CUDA),&v->spptr);CHKERRQ(ierr);
> > veccuda = (Vec_CUDA*)v->spptr;
> > if (v->valid_GPU_array != PETSC_OFFLOAD_CPU) {
> > err =
> cudaMalloc((void**)&veccuda->GPUarray_allocated,sizeof(PetscScalar)*((PetscBLASInt)v->map->n));CHKERRCUDA(err);
> > veccuda->GPUarray = veccuda->GPUarray_allocated;
> > err = cudaStreamCreate(&stream);CHKERRCUDA(err);
> > veccuda->stream = stream;
> > veccuda->hostDataRegisteredAsPageLocked = PETSC_FALSE;
> > if (v->valid_GPU_array == PETSC_OFFLOAD_UNALLOCATED) {
> > if (v->data && ((Vec_Seq*)v->data)->array) {
> > v->valid_GPU_array = PETSC_OFFLOAD_CPU;
> > } else {
> > v->valid_GPU_array = PETSC_OFFLOAD_GPU;
> > }
> > }
> > }
> > }
> > PetscFunctionReturn(0);
> > }
> >
> >
> >
> >
> >
> > > On Jul 27, 2019, at 10:40 AM, Mark Adams <mfadams at lbl.gov
> <mailto:mfadams at lbl.gov>> wrote:
> > >
> > > Yea, I just figured out the problem. VecDuplicate_MPICUDA
> did not call PinToCPU or even copy pinnedtocpu. It just copied
> ops, so I added and am testing:
> > >
> > > ierr =
> VecCreate_MPICUDA_Private(*v,PETSC_TRUE,w->nghost,0);CHKERRQ(ierr);
> > > vw = (Vec_MPI*)(*v)->data;
> > > ierr = PetscMemcpy((*v)->ops,win->ops,sizeof(struct
> _VecOps));CHKERRQ(ierr);
> > > ierr = VecPinToCPU(*v,win->pinnedtocpu);CHKERRQ(ierr);
> > >
> > > Thanks,
> > >
> > > On Sat, Jul 27, 2019 at 11:33 AM Smith, Barry F.
> <bsmith at mcs.anl.gov <mailto:bsmith at mcs.anl.gov>> wrote:
> > >
> > > I don't understand the context. Once a vector is pinned
> to the CPU the flag should be PETSC_OFFLOAD_CPU permanently
> until the pin to cpu is turned off. Do you have a pinned vector
> that has the value PETSC_OFFLOAD_GPU? For example here it is
> set to PETSC_OFFLOAD_CPU
> > >
> > > PetscErrorCode VecPinToCPU_MPICUDA(Vec V,PetscBool pin)
> > > {
> > > ....
> > > if (pin) {
> > > ierr = VecCUDACopyFromGPU(V);CHKERRQ(ierr);
> > > V->valid_GPU_array = PETSC_OFFLOAD_CPU; /* since the
> CPU code will likely change values in the vector */
> > >
> > >
> > > Is there any way to reproduce the problem?
> > >
> > > Barry
> > >
> > >
> > >
> > >
> > > > On Jul 27, 2019, at 10:28 AM, Mark Adams <mfadams at lbl.gov
> <mailto:mfadams at lbl.gov>> wrote:
> > > >
> > > > I'm not sure what to do here. The problem is that
> pinned-to-cpu vectors are calling VecCUDACopyFromGPU here.
> > > >
> > > > Should I set x->valid_GPU_array to something else, like
> PETSC_OFFLOAD_CPU, in PinToCPU so this block of code i s not
> executed?
> > > >
> > > > PetscErrorCode VecGetArray(Vec x,PetscScalar **a)
> > > > {
> > > > PetscErrorCode ierr;
> > > > #if defined(PETSC_HAVE_VIENNACL)
> > > > PetscBool is_viennacltype = PETSC_FALSE;
> > > > #endif
> > > >
> > > > PetscFunctionBegin;
> > > > PetscValidHeaderSpecific(x,VEC_CLASSID,1);
> > > > ierr = VecSetErrorIfLocked(x,1);CHKERRQ(ierr);
> > > > if (x->petscnative) {
> > > > #if defined(PETSC_HAVE_VIENNACL) || defined(PETSC_HAVE_CUDA)
> > > > if (x->valid_GPU_array == PETSC_OFFLOAD_GPU) {
> > > > #if defined(PETSC_HAVE_VIENNACL)
> > > > ierr =
> PetscObjectTypeCompareAny((PetscObject)x,&is_viennacltype,VECSEQVIENNACL,VECMPIVIENNACL,VECVIENNACL,"");CHKERRQ(ierr);
> > > > if (is_viennacltype) {
> > > > ierr = VecViennaCLCopyFromGPU(x);CHKERRQ(ierr);
> > > > } else
> > > > #endif
> > > > {
> > > > #if defined(PETSC_HAVE_CUDA)
> > > > ierr = VecCUDACopyFromGPU(x);CHKERRQ(ierr);
> > > > #endif
> > > > }
> > > > } else if (x->valid_GPU_array ==
> PETSC_OFFLOAD_UNALLOCATED) {
> > > > #if defined(PETSC_HAVE_VIENNACL)
> > > > ierr =
> PetscObjectTypeCompareAny((PetscObject)x,&is_viennacltype,VECSEQVIENNACL,VECMPIVIENNACL,VECVIENNACL,"");CHKERRQ(ierr);
> > > > if (is_viennacltype) {
> > > > ierr = VecViennaCLAllocateCheckHost(x);CHKERRQ(ierr);
> > > > } else
> > > > #endif
> > > > {
> > > > #if defined(PETSC_HAVE_CUDA)
> > > > ierr = VecCUDAAllocateCheckHost(x);CHKERRQ(ierr);
> > > > #endif
> > > > }
> > > > }
> > > > #endif
> > > > *a = *((PetscScalar**)x->data);
> > > > } else {
> > > >
> > > >
> > > > On Tue, Jul 23, 2019 at 9:18 PM Smith, Barry F.
> <bsmith at mcs.anl.gov <mailto:bsmith at mcs.anl.gov>> wrote:
> > > >
> > > > Yes, it needs to be able to switch back and forth
> between the CPU and GPU methods so you need to move into it the
> setting of the methods that is currently directly in the create
> method. See how MatConvert_SeqAIJ_SeqAIJViennaCL() calls ierr =
> MatPinToCPU_SeqAIJViennaCL(A,PETSC_FALSE);CHKERRQ(ierr); to set
> the methods for the GPU initially.
> > > >
> > > > Barry
> > > >
> > > >
> > > > > On Jul 23, 2019, at 7:32 PM, Mark Adams
> <mfadams at lbl.gov <mailto:mfadams at lbl.gov>> wrote:
> > > > >
> > > > >
> > > > > What are the symptoms of it not working? Does it
> appear to be still copying the matrices to the GPU? then running
> the functions on the GPU?
> > > > >
> > > > >
> > > > > The object is dispatching the CUDA mat-vec etc.
> > > > >
> > > > > I suspect the pinning is incompletely done for CUDA
> (and MPIOpenCL) matrices.
> > > > >
> > > > >
> > > > > Yes, git grep MatPinToCPU shows stuff for ViennaCL but
> not CUDA.
> > > > >
> > > > > I guess I can add something like this below. Do we need
> to set the device methods? They are already set when this method
> is set, right?
> > > > >
> > > > > We need the equivalent of
> > > > >
> > > > > static PetscErrorCode MatPinToCPU_SeqAIJViennaCL(Mat
> A,PetscBool flg)
> > > > > {
> > > > > PetscFunctionBegin;
> > > > > A->pinnedtocpu = flg;
> > > > > if (flg) {
> > > > > A->ops->mult = MatMult_SeqAIJ;
> > > > > A->ops->multadd = MatMultAdd_SeqAIJ;
> > > > > A->ops->assemblyend = MatAssemblyEnd_SeqAIJ;
> > > > > A->ops->duplicate = MatDuplicate_SeqAIJ;
> > > > > } else {
> > > > > A->ops->mult = MatMult_SeqAIJViennaCL;
> > > > > A->ops->multadd = MatMultAdd_SeqAIJViennaCL;
> > > > > A->ops->assemblyend = MatAssemblyEnd_SeqAIJViennaCL;
> > > > > A->ops->destroy = MatDestroy_SeqAIJViennaCL;
> > > > > A->ops->duplicate = MatDuplicate_SeqAIJViennaCL;
> > > > > }
> > > > > PetscFunctionReturn(0);
> > > > > }
> > > > >
> > > > > for MPIViennaCL and MPISeqAIJ Cusparse but it doesn't
> look like it has been written yet.
> > > > >
> > > > >
> > > > > >
> > > > > > It does not seem to work. It does not look like CUDA
> has an MatCreateVecs. Should I add one and copy this flag over?
> > > > >
> > > > > We do need this function. But I don't see how it
> relates to pinning. When the matrix is pinned to the CPU we want
> it to create CPU vectors which I assume it does.
> > > > >
> > > > >
> > > > > >
> > > > > > Mark
> > > > >
> > > >
> > >
> >
>
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