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Bug #1721

Incorrect forces with DD and GPUs with partially empty boxes

Added by Berk Hess over 2 years ago. Updated over 2 years ago.

Status:
Closed
Priority:
High
Assignee:
Category:
mdrun
Target version:
Affected version - extra info:
4.6, master
Affected version:
Difficulty:
uncategorized
Close

Description

When there are non-local atoms but no non-local interactions, the CUDA kernel is not called, but the F reduction is called due to a stupid typo. This situation is very rare, which is why it hasn't been noticed.

Associated revisions

Revision fc8a5624 (diff)
Added by Berk Hess over 2 years ago

Fixed GPU non-local F copy local conditional

With domain decomposition and GPUs the copy of the non-local part of
the host memory force buffer to the force array was conditional on
the local instead of the non-local list size. This meant that with
an empty non-local list and non-empty local list outdated non-local
forces would be copied. Conversely, with an empty local list all
non-local forces would not be added. Both things can only happen
in systems with partially empty boxes and then only rarely.
Having the local kernel, D2H copyback and F reduction called
conditionally is not useful in practice, so they are now unconditional
to avoid complicating the code.
Fixes #1721.

Change-Id: I06731b0055a4fb5a16168e7180964e0b87443b0f

Revision 56a67d7c (diff)
Added by Berk Hess over 2 years ago

Fixed CUDA error with empty domains

Recent commit fc8a5624 introduced empty CUDA kernel calls when there
are empty domains. This seems not be allowed by CUDA (we get errors).
Fixed #1734. Refs #1721.

Change-Id: Ifd32a55c8d6756c93a0fcaba29983ae326abc569

History

#1 Updated by Gerrit Code Review Bot over 2 years ago

Gerrit received a related patchset '1' for Issue #1721.
Uploader: Berk Hess ()
Change-Id: I06731b0055a4fb5a16168e7180964e0b87443b0f
Gerrit URL: https://gerrit.gromacs.org/4540

#2 Updated by Berk Hess over 2 years ago

  • Status changed from New to Fix uploaded
  • Target version set to 5.0.5

#3 Updated by Mark Abraham over 2 years ago

  • Status changed from Fix uploaded to Closed

#4 Updated by Gerrit Code Review Bot over 2 years ago

Gerrit received a related patchset '1' for Issue #1721.
Uploader: Berk Hess ()
Change-Id: Ifd32a55c8d6756c93a0fcaba29983ae326abc569
Gerrit URL: https://gerrit.gromacs.org/4583

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