Duane Merrill (NVIDIA) - GPU Technology Conference

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Available bandwidth (GB/s)1) Cooperative data movement (queuing)Problem:Need shared work “queues”<strong>GPU</strong> rate-limits (C2050):16 billion vertex-identifiers / sec (124 GB/s)1000100124.3Only 67M global-atomics / sec (238xslowdown)Only 600M smem-atomics / sec (27xslowdown)1010.54Solution:Compute enqueue offsets using prefix-sum0.11:1 1:8 1:64 1:512 1:4096 1:32768 1:262144Frequency of atomic ops per vertex dequeued26
Prefix sum for allocationAllocationrequirementResult ofprefix sumOutputA 2 C 1 0 D 3t 0 t 1 t 2 t 3A 0 2 C 3 D 3t 0 t 1 t 2 t 30 1 2 3 4 5Each output is computed to be the sumof the previous inputsO(n) workUse results as a scatter offsetsFits the <strong>GPU</strong> machine model wellProceed at copy-bandwidthOnly ~8 thread-instructions perinput27
Page 1 and 2: Duane Merrill (NVIDIA)Michael Garla
Page 4 and 5: Sparse graphsGraph G(V, E) where n
Page 6: Compressed sparse row (CSR) represe
Page 9 and 10: Breadth-first search (BFS)1. Pick a
Page 11 and 12: Breadth-first search (BFS)1. Pick a
Page 13 and 14: BFS applicationsAlgorithmic primiti
Page 15 and 16: Common parallelization strategies
Page 17 and 18: Quadratic-work approach1. Inspect e
Page 19 and 20: Quadratic-work approach1. Inspect e
Page 21 and 22: Vertices (millions)Vertices (millio
Page 23 and 24: Referenced vertex identifiers(milli
Page 25: Linear-work challenges for parallel
Page 29 and 30: Data-flow of efficient CTA scan(gra
Page 31 and 32: 2) Poor load balancing within SIMD
Page 33 and 34: 4) SIMD simultaneous discovery0 1 2
Page 35 and 36: Single-socket comparisonGraphSpy Pl
Page 38 and 39: Maximal independent setA vertex sub
Page 40 and 41: MIS applicationsGraph coloring (ver
Page 42 and 43: The sequential algorithm• Repeate
Page 44 and 45: Data-parallel GPU approach• Input
Page 46 and 47: SummaryPurely data-parallel approac
Page 48 and 49: GTC 2013:The Premier Event in Accel
Page 50 and 51: Comparison of expansion techniques5
Page 52 and 53: 10 9 edges / secnormalizedCompariso
Page 54: 10 9 edges / secnormalizedMulti-GPU

Duane Merrill (NVIDIA) - GPU Technology Conference

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