From: bangerth Date: Wed, 3 Aug 2011 15:44:17 +0000 (+0000) Subject: Be a bit more carefully when we actually call VecAssembleBegin/End for PETSc vectors. X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=10bb47134ac1d62b5710adc7d1ee9ee029a0728f;p=dealii-svn.git Be a bit more carefully when we actually call VecAssembleBegin/End for PETSc vectors. git-svn-id: https://svn.dealii.org/trunk@24003 0785d39b-7218-0410-832d-ea1e28bc413d --- diff --git a/deal.II/doc/news/changes.h b/deal.II/doc/news/changes.h index 08d6c50b3e..8f039d9d82 100644 --- a/deal.II/doc/news/changes.h +++ b/deal.II/doc/news/changes.h @@ -87,13 +87,6 @@ code using e.g. Tensor<1,dim> remains valid.
(Martin Kronbichler, 2011/08/02) - -
  • Fixed: The function VectorTools::create_right_hand_side now also works -for objects of type hp::DoFHandler with different finite elements. -
    -(Daniel Gerecht, 2011/07/20) - -
  • Fixed: deal.II can link with Trilinos but previously it required a very specific set of Trilinos sub-libraries; if Trilinos had been compiled with a larger set of sub-libraries, linking would sometimes fail. This @@ -245,6 +238,18 @@ should be fixed now.

    Specific improvements

      +
    1. Improved: The PETScWrapper::VectorBase class was rather generous in +calling the PETSc VecAssembleBegin/End functions that incur +communication in the %parallel case and are therefore causes of potential +slowdowns. This has been improved. +
      +(Wolfgang Bangerth, 2011/08/03) + +
    2. Fixed: The function VectorTools::create_right_hand_side now also works +for objects of type hp::DoFHandler with different finite elements. +
      +(Daniel Gerecht, 2011/07/20) +
    3. Improved: Evaluation of Lagrangian basis functions has been made stable by exchanging polynomial evaluation from the standard form $a_n x^n+\ldots+a_1 x + a_0$ to a product of linear factors, diff --git a/deal.II/include/deal.II/lac/petsc_vector_base.h b/deal.II/include/deal.II/lac/petsc_vector_base.h index 0f0ca45c25..8bf647553c 100644 --- a/deal.II/include/deal.II/lac/petsc_vector_base.h +++ b/deal.II/include/deal.II/lac/petsc_vector_base.h @@ -906,7 +906,8 @@ namespace PETScWrappers const VectorReference & VectorReference::operator = (const PetscScalar &value) const { - if (vector.last_action != VectorBase::LastAction::insert) + // if the last action was an addition, we need to flush buffers + if (vector.last_action == VectorBase::LastAction::add) { int ierr; ierr = VecAssemblyBegin (vector); @@ -937,7 +938,8 @@ namespace PETScWrappers const VectorReference & VectorReference::operator += (const PetscScalar &value) const { - if (vector.last_action != VectorBase::LastAction::add) + // if the last action was a set operation, we need to flush buffers + if (vector.last_action == VectorBase::LastAction::insert) { int ierr; ierr = VecAssemblyBegin (vector); @@ -945,10 +947,10 @@ namespace PETScWrappers ierr = VecAssemblyEnd (vector); AssertThrow (ierr == 0, ExcPETScError(ierr)); - - vector.last_action = VectorBase::LastAction::add; } + vector.last_action = VectorBase::LastAction::add; + // we have to do above actions in any // case to be consistent with the MPI // communication model (see the @@ -979,7 +981,8 @@ namespace PETScWrappers const VectorReference & VectorReference::operator -= (const PetscScalar &value) const { - if (vector.last_action != VectorBase::LastAction::add) + // if the last action was a set operation, we need to flush buffers + if (vector.last_action == VectorBase::LastAction::insert) { int ierr; ierr = VecAssemblyBegin (vector); @@ -987,11 +990,11 @@ namespace PETScWrappers ierr = VecAssemblyEnd (vector); AssertThrow (ierr == 0, ExcPETScError(ierr)); - - vector.last_action = VectorBase::LastAction::add; } - // we have to do above actions in any + vector.last_action = VectorBase::LastAction::add; + + // we have to do above actions in any // case to be consistent with the MPI // communication model (see the // comments in the documentation of @@ -1022,7 +1025,8 @@ namespace PETScWrappers const VectorReference & VectorReference::operator *= (const PetscScalar &value) const { - if (vector.last_action != VectorBase::LastAction::insert) + // if the last action was an addition, we need to flush buffers + if (vector.last_action == VectorBase::LastAction::add) { int ierr; ierr = VecAssemblyBegin (vector); @@ -1030,10 +1034,10 @@ namespace PETScWrappers ierr = VecAssemblyEnd (vector); AssertThrow (ierr == 0, ExcPETScError(ierr)); - - vector.last_action = VectorBase::LastAction::insert; } + vector.last_action = VectorBase::LastAction::insert; + // we have to do above actions in any // case to be consistent with the MPI // communication model (see the @@ -1066,7 +1070,8 @@ namespace PETScWrappers const VectorReference & VectorReference::operator /= (const PetscScalar &value) const { - if (vector.last_action != VectorBase::LastAction::insert) + // if the last action was a set operation, we need to flush buffers + if (vector.last_action == VectorBase::LastAction::insert) { int ierr; ierr = VecAssemblyBegin (vector); @@ -1074,10 +1079,10 @@ namespace PETScWrappers ierr = VecAssemblyEnd (vector); AssertThrow (ierr == 0, ExcPETScError(ierr)); - - vector.last_action = VectorBase::LastAction::insert; } + vector.last_action = VectorBase::LastAction::insert; + // we have to do above actions in any // case to be consistent with the MPI // communication model (see the diff --git a/deal.II/source/lac/petsc_vector_base.cc b/deal.II/source/lac/petsc_vector_base.cc index 30b6a33ed9..e31f29a012 100644 --- a/deal.II/source/lac/petsc_vector_base.cc +++ b/deal.II/source/lac/petsc_vector_base.cc @@ -393,11 +393,22 @@ namespace PETScWrappers void VectorBase::compress () { + // note that one may think that we only need to do something + // if in fact the state is anything but LastAction::none. but + // that's not true: one frequently gets into situations where + // only one processor (or a subset of processors) actually writes + // something into a vector, but we still need to call + // VecAssemblyBegin/End on all processors, even those that are + // still in LastAction::none state int ierr; ierr = VecAssemblyBegin(vector); AssertThrow (ierr == 0, ExcPETScError(ierr)); ierr = VecAssemblyEnd(vector); AssertThrow (ierr == 0, ExcPETScError(ierr)); + + // reset the last action field to indicate that we're back to + // a pristine state + last_action = VectorBase::LastAction::none; } @@ -1110,7 +1121,8 @@ namespace PETScWrappers const PetscScalar *values, const bool add_values) { - if (last_action != VectorBase::LastAction::insert) + // if the last action was a set operation, we need to flush buffers + if (last_action == VectorBase::LastAction::insert) { int ierr; ierr = VecAssemblyBegin (vector); @@ -1118,6 +1130,10 @@ namespace PETScWrappers ierr = VecAssemblyEnd (vector); AssertThrow (ierr == 0, ExcPETScError(ierr)); + + // reset the last action field to indicate that we're back to + // a pristine state + last_action = VectorBase::LastAction::none; } // VecSetValues complains if we @@ -1146,6 +1162,8 @@ namespace PETScWrappers AssertThrow (ierr == 0, ExcPETScError(ierr)); } + // set the mode here, independent of whether we have actually + // written elements or whether the list was empty last_action = LastAction::insert; }