Notes

N-Body & SPH

• N-Body:
  • (parallel) tree construction
    • bounding box
    • domain list
    • tree
    • common coarse tree
  • (parallel) pseudo-particles
  • (parallel) gravitational force
• SPH with N-Body:
  • (parallel) tree construction
    • bounding box
    • domain list
    • tree
    • common coarse tree
  • (parallel) pseudo-particles
  • (parallel) gravitational force
  • (parallel) SPH forces
• SPH without N-Body:
  • (parallel) tree construction
    • bounding box
    • domain list
    • tree
    • common coarse tree
  • (parallel) SPH forces

Thus 4 modules:

• (parallel) tree construction
• (parallel) pseudo-particles
• (parallel) gravitational force
• (parallel) SPH forces

TODO

• compile time
• compiler directive constants as varialbles!?
• overloaded atomicAdd() for double input
  • atomicAdd with doubles
    
• remove pseudo-particle calculations within buildTree() for SPH without gravity
  • compiler directive #GRAVITY!?
• remove Helper instance from compTheta()
• device_rhs.cuh/cu needed? move to helper.cuh/cu

Ideas

• ...

Problems, Challenges, Improvements, ...

• smoothing in gravity::computeForces()
  • how to avoid $r = 0$
  • how to avoid $r \approx 0$
• symbolicForce: insert cell itself or children
• 1D Space filling curve
• Performance:
  • kernel call buildDomainTree() with more than one thread
  • kernel call createDomainList() with more than one thread
• Structure
  • how to structure main function/functionality?
  • generalize functionality
  • naming (conventions)
  • where to put which function

Generalizing functions/functionality

• particle exchange process for N-Body and SPH
• ...

Buffers

id	description	functions	type	size	location	intersection
1	mutex/lock	computeBoundingBox	int	1	device

| | | | | | | 2 | arranging particle (entries) particles process | arrangeParticleEntries | int | numParticlesLocal | device | | 3 | arranging particle (entries) particles process sorted | arrangeParticleEntries | int | numParticlesLocal | device | | 4 | arranging particle (entries) sorted entries | arrangeParticleEntries | float | numParticlesLocal | device | | 5 | arranging particle (entries) sorted entries | arrangeParticleEntries | int | numParticlesLocal | device | | | | | | | | | 6 | sorting domain list (entries) unsorted entries | sortArray() within parallel_pseudoParticles() | float | domainListSize | device | | 7 | sorting domain list (entries) sorted entries | sortArray() within parallel_pseudoParticles() | float | domainListSize | device | | | | | | | | | 8 | symbolic force: mark send indices | Gravity:: intermediateSymbolicForce(), symbolicForce(), collectSendIndices() | int | numNodes | device | | 9 | symbolic force: collected collected particle (entries) | collectValues(), sendParticles() | float | up to 50% of numNodes | device | | 10 | ??? symbolic force: collected particle (entries) | collectValues(), sendParticles() | int | up to 50% of numNodes | device | | 11 | symbolic force: send indices (particles) | collectSendIndices(), sendParticles() | int | up to 50% of numParticles | device | | 12 | symbolic force: send indices (pseudo-particles) | collectSendIndices(), sendParticles() | int | up to 50% of numNodes | device | | 13 | symbolic force: send levels (pseudo-particles) | collectSendIndices(), sendParticles() | int | up to 50% of numNodes | device | | 14 | symbolic force: receive levels (pseudo-particles) | collectSendIndices(), sendParticles() | int | up to 50% of numNodes | device | | 15 | symbolic force: send count (particles) | collectSendIndices() | int | numProcesses | device | | 16 | symbolic force: send count (pseudo-particles) | collectSendIndices() | int | numProcesses | device | | | | | | | | | 17 | sph symbolic force: mark send indices | SPH:: intermediateSymbolicForce(), symbolicForce(), collectSendIndices() | int | numParticles | device | | 18 | sph symbolic force: send indices | collectSendIndices(), sendParticles() | int | up to 50% of numParticles | device | | 19 | sph symbolic force: collected particle (entries) | collectValues(), sendParticles() | float | up to 50% of numParticles | device | | 20 | sph symbolic force: collected particle (entries) | collectValues(), sendParticles() | int | up to 50% of numParticles | device | | 21 | sph symbolic force: send count (particles) | collectSendIndices() | int | numProcesses | device | | 22 | sph symbolic force: send count (pseudo-particles) | collectSendIndices() | int | numProcesses | device | | | | | | | | | 23 | file I/O | particles2file() | keyType/unsigned long | numParticlesLocal | device | |