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Colloquium – Tyler Sorensen
March 6, 2019 @ 10:00 am - 11:00 am
March 6, 2019
lecture – 10:00am
Host: John Regehr
Reasoning about Heterogenous Computing
Heterogeneous system designs have allowed computing efficiency to scale past fundamental constraints of transistors. Such systems are now the computation workhorses behind everyday technology, from speech recognition trained on clusters of GPUs, to efficient SoC designs in mobile phones. However, programming for these systems presents many challenges, specifically in orchestrating synchronization. Examining general purpose GPU (GPGPU) programming is a pragmatic start towards general heterogeneous reasoning, as GPGPU programming models expose hardware specialization and heterogeneous-aware constructs. In this talk, I discuss my work in this area, which has identified important areas of under-specification in GPGPU programming and laid the foundations for specification repairs. First, I will present work on testing memory consistency models, i.e. the rules governing fine-grained communication, for GPGPUs. This work exposed wide-spread confusion in the GPGPU community, including identifying programming errors in two Nvidia-endorsed textbooks. Second, I will present work on GPGPU forward progress models, which defines a progress abstraction that allows cross-vendor GPGPU global barrier synchronization. This can then be used in an optimization for GPGPU graph traversal applications, achieving over a 10x speedup on Intel and AMD GPUs. The talk concludes by showing that GPGPU reasoning is a natural foundation for future work targeting general heterogeneous programming.
Tyler Sorensen is a PostDoc at Princeton University in Professor Margaret Martonosi’s architecture group working on designing new heterogenous systems. He recieved his PhD from Imperial College London under the supervision of Dr. Alastair Donaldson. His thesis work involved rigorous reasoning about GPGPU programming, with an emphasis on fine-grained synchronisation idioms. This work has been published widely and received two conference distinguished paper awards (PLDI’18 and FSE’17). Tyler recieved his MS/BS from University of Utah, where he recieved the 2014 Outstanding Senior Award. He has done internships at both Microsoft Research and Nvidia.