[petsc-dev] Using multiple mallocs with PETSc

[Jed Brown]

Jeff Hammond <jeff.science at gmail.com> writes:
> My intuition is that any HPC code that benefits from mapping the zero page
> vs memset is doing something wrong.

The relevant issue is the interface, from

  a = malloc(size);
  // need to fault the memory using first-touch
  #pragma omp parallel
  {
    // memset my part
  }
  
  // ...
  #pragma omp parallel
  {
    // Use a[] knowing it starts zeroed
  }

versus

  a = calloc(size,1);
  
  // ...
  #pragma omp parallel
  {
    // Use a[] knowing it starts zeroed
  }
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