Stack-less SIMT reconvergence at low cost

Caroline Collange (1)

1 ARENAIRE - Computer arithmetic

Parallel architectures following the SIMT model such as GPUs benefit from application regularity by issuing concurrent threads running in lockstep on SIMD units. As threads take different paths across the control-flow graph, lockstep execution is partially lost, and must be regained whenever possible in order to maximize the occupancy of SIMD units. In this paper, we propose a technique to handle SIMT control divergence that operates in constant space and handles indirect jumps and recursion. We describe a possible implementation which leverage the existing memory divergence management unit, ensuring a low hardware cost. In terms of performance, this solution is at least as efficient as existing techniques.

Mots clés: Control-flow reconvergence; SIMT; SIMD; GPU

Domaines: Architectures Matérielles [cs.AR]

Caroline Collange. Stack-less SIMT reconvergence at low cost. [Research Report] ENS Lyon. 2011. ⟨hal-00622654⟩