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Data movement latency when using on-chip accelerators in emerging heterogeneous architectures is a serious performance bottleneck. While hardware/software mechanisms such as peer-to-peer DMA between producer/consumer accelerators allow bypassing main memory and significantly reduce main memory contention, schedulers in both the hardware and software domains remain oblivious to their presence. Instead, most contemporary schedulers tend to be deadline-driven, with improved utilization and/or throughput serving as secondary or co-primary goals. This lack of focus on data communication will only worsen execution times as accelerator latencies reduce. In this paper, we present RELIEF (RElaxing Least-laxIty to Enable Forwarding), an online least laxity-driven accelerator scheduling policy that relieves memory pressure in accelerator-rich architectures via data movement-aware scheduling. RELIEF leverages laxity (time margin to a deadline) to opportunistically utilize available hardware data forwarding mechanisms while minimizing quality-of-service (QoS) degradation and unfairness. RELIEF achieves up to 50% more forwards compared to state-of- the-art policies, reducing main memory traffic and energy consumption by up to 32% and 18%, respectively. At the same time, RELIEF meets 14% more task deadlines on average and reduces worst-case deadline violation by 14%, highlighting QoS and fairness improvements.
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Laius: Towards Latency Awareness and Improved Utilization of Spatial Multitasking Accelerators in Datacenters
Datacenters use accelerators to provide the significant compute throughput required by emerging user-facing services. The diurnal user access pattern of user-facing services provides a strong incentive to co-located applications for better accelerator utilization, and prior work has focused on enabling co-location on multicore processors and traditional non-preemptive accelerators. However, current accelerators are evolving towards spatial multitasking and introduce a new set of challenges to eliminate QoS violation. To address this open problem, we explore the underlying causes of QoS violation on spatial multitasking accelerators. In response to these causes, we propose Laius, a runtime system that carefully allocates the computation resource to co-located applications for maximizing the throughput of batch applications while guaranteeing the required QoS of user-facing services. Our evaluation on a Nvidia RTX 2080Ti GPU shows that Laius improves the utilization of spatial multitasking accelerators by 20.8%, while achieving the 99%-ile latency target for user-facing services.
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- Award ID(s):
- 1823005
- PAR ID:
- 10113420
- Date Published:
- Journal Name:
- Proceedings of the ACM International Conference on Supercomputing
- Page Range / eLocation ID:
- 58 to 68
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1145/3330345.3330351
