On 11.06.2015 14:07, David McGiven wrote:
Your 1-3% claim is based on the webpage you linked ?
Is it reliable to compare GPU performances for gromacs with those of 3D
videogames ?
OK, you got me on this. As much as I'd wish I cannot
really back up my claim of comparability. I have been
out of office for one week but did some tests here
for myself today.
The system is Haswell/E (i7-5820K), GPU is single GTX-980
(the "normal" Gigabyte Model), the test run is ADH-cubic-vsites
(reaction field) from the bottom of the Gromacs acceleration page
(http://www.gromacs.org/GPU_acceleration).
I can explicitly set the PCIe-x16 slots to 1.0, 2.0, and 3.0
(which I did). Theoretically (and practically), PCIe-x16 2.0
should be relatively close in bandwidth to PCIe-x8 3.0, so this
should give some hints as what to expect.
adh-cubic-vsites/rf - ns/day:
PCIE-x16/1.0 54.46
PCIE-x16/2.0 61.81
PCIE-x16/3.0 64.52
percentage related to PCIE-x16/3.0
PCIE-x16/1.0 84.4
PCIE-x16/2.0 95.8
PCIE-x16/3.0 100
(each value = avg. of three runs)
Therefore one could support the hypothesis
that using one card in x16 and one in x8
would probably show a performance penalty
of around 5% on the x8 card.
Regards
M.
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