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<p>While the GlobalGridView seems to work (what ever this means),
some other parts of the MR are more experimental and, e.g., the
parallel poisson equation does not work correctly. Also, it is
quiet inefficient, since the same communication needs to be
performed multiple time to build up the parallel indexset.
Essentially, to build up the GlobalIndexSet we need at least two
communications over the grid and then the same communications
again on the ParallelIndexSet and RemoteIndices. This is not very
efficient. If the GlobalIndexSet is just used to identy uniquely
all DOFs, it is not worth building this up. A better approach is
something that can be computed locally, to have a global
indentification of all DOFs, e.g. a global ID-Set for basis
functions.<br>
</p>
<p>With just the globalIndexSet one cannot directly build any
parallel linear algebra. One needs more information about the
overlap of DOFs and who has to communicate with whom. This is not
encoded in the GlobalIndexSet, but in the RemoteIndices. A
ScalarProduct also needs the information whether the local DOF
should be added up to the global value or not.</p>
<p>There are a lot of open questions. I do not have answers for all
of them.<br>
</p>
<div class="moz-cite-prefix">Am 11.11.21 um 08:12 schrieb Oliver
Sander:<br>
</div>
<blockquote type="cite"
cite="mid:0feef671-09d9-98f7-016f-991965fc833b@tu-dresden.de">
<br>
Hi Simon,
<br>
<br>
<blockquote type="cite">So far so good. [The GlobalGridView] works
fine and is implemented in the branch
<br>
feature/parallel-grid-view. </blockquote>
<br>
thank you! I recently realized that this is what I need to
replace
<br>
a lot of hand-written goo in a central part of my code. Would you
<br>
be able to open a merge request to make code review easier?
<br>
<br>
Best,
<br>
Oliver
<br>
<br>
<br>
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<pre class="moz-signature" cols="72">--
Dr. Simon Praetorius
Institut für Wissenschaftliches Rechnen
Fakultät Mathematik
Technische Universität Dresden
Tel.: TUD-34432
Mail: <a class="moz-txt-link-abbreviated" href="mailto:simon.praetorius@tu-dresden.de">simon.praetorius@tu-dresden.de</a>
Web: <a class="moz-txt-link-freetext" href="https://tu-dresden.de/mn/math/wir/das-institut/beschaeftigte/simon-praetorius">https://tu-dresden.de/mn/math/wir/das-institut/beschaeftigte/simon-praetorius</a></pre>
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