Tree Poisson solver

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Algorithm overview • Parameters: ◮ tree limangle (θ lim ) . . . REAL . . . 1.0 - 0.5 ◮ tree ilist . . . INTEGER . . . 0 or 1 • Algorithm: (as in Grid solvePoisson()) if (grid changed .eq. 1) then call treeComBlkProperties() (nodetype, lrene, child, neigh, coords) 1% if (tree ilist .eq. 1) call treeFindNeighbours() 0% endif call gr treeBuildTree() 3% call gr treeExchangeTrees() 3% call gr treePotential(idensvar, ipotvar) 93% call gr treeDestroyTree() 0% ◮ routines that include MPI communication marked red ◮ relative times for a collapse of the BE sphere (512 CPUs, θ lim = 0.5, 76000 leaf blocks) Richard Wünsch, Flash workshop at the Hamburg Observatory, 15th February 2012 2/26
Communication of grid properties • treeComBlkProperties() ◮ nodetype, lrene, child, neigh and cell coords in each block ◮ memory: MAXBLOCKS × nCPUs × (16×INT + 27×REAL) ◮ for MAXBLOCKS = 1000, nCPU = 1000 → 300 MB ◮ only active values communicated • treeFindNeighbours() (needed by interaction lists) ◮ nds 26 neighbours in all (incl. diagonal) directions ◮ tr surbox(2, 27, MAXBLOCKS) → records block number and cpu of each neighbour Richard Wünsch, Flash workshop at the Hamburg Observatory, 15th February 2012 3/26
Page 1: Tree-based self-gravity solver R. W
Page 5 and 6: • for 8 × 8 × 8 blocks: Block t
Page 7 and 8: • 5 types of iteractions: 1. cell
Page 9 and 10: Test: Bonnor-Ebert sphere • mass:
Page 11 and 12: Flash 3: error in Φ (lref min = lr
Page 13 and 14: Flash 3: error in F r (lref min = l
Page 15 and 16: Flash 3: error in F r (lref min = 1
Page 17 and 18: Flash 2: error in F r (lref min = 1
Page 19 and 20: Flash 3, BES: relative time 1 other
Page 21 and 22: Flash 2, shell: time(nCPUs) 70,000
Page 23 and 24: Flash 3: time(number of blocks) sec
Page 25 and 26: GPU version • tree walk ported to
Page 27: Download at: http://galaxy.asu.cas.

Tree Poisson solver

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