[petsc-dev] [petsc-users] Patch to release extra memoty to aij matrix

[Barry Smith]

On Apr 10, 2011, at 1:06 PM, Jed Brown wrote:

> 2011/4/10 Gong Ding <gdiso at ustc.edu>
> This is the patch file to aij.c, which will release excessively preallocated memory at MatAssemblyEnd.
> It had been tested in the past several months, both for serial and parallel.
> 
> Hope this patch can be accepted.
> 
> I'm not sure we can do this unconditionally because it can significantly increase the peak memory usage. The most common case (I think) is that preallocation is only slightly more than necessary in which case the extra space is not very significant. Do we need to add a MatOption for this?

   It has to be made optional in some way. Using the MatSetOption() approach seems a reasonable way to make it optional. So I would ask Gong Ding to make it optional and submit a new patch when that is done.

    Thanks

    Barry