Change order of particles at initialization #79
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Does this PR have any impact on the GPU performance? |
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In theory: no, since the particles are reordered (i.e. sorted) anyway on the GPU. And in practice: I tested the performance on the GPU (2000x400 box full of electrons) and saw no difference between the |
MKirchen
approved these changes
Jul 10, 2017
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Before this pull request, the particles were initialized such that, when going through the array of particles in order:
thetachanges the fastest (whilezandrremain constant)zchangesrchanges the slowestHowever, in order to optimize cache reuse, in the current deposition and gathering, it is better to have the following order:
thetachanges the fastest (whilezandrremain constant)rchangeszchanges the slowestThis pull request implements the above change.
Although this order is theoretically supposed to be more efficient (on CPU), I did not observe any significant speedup in practice. I think it still makes sense to merge this PR, as this is the most logical order for the particles to be in.