Dan Gibson
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Aquila: A unified, low-latency fabric for datacenter networks
Hema Hariharan
Eric Lance
Moray Mclaren
Stephen Wang
Zhehua Wu
Sunghwan Yoo
Raghuraman Balasubramanian
Prashant Chandra
Michael Cutforth
Peter James Cuy
David Decotigny
Rakesh Gautam
Rick Roy
Zuowei Shen
Ming Tan
Ye Tang
Monica C Wong-Chan
Joe Zbiciak
Aquila: A unified, low-latency fabric for datacenter networks (2022)
Preview abstract
Datacenter workloads have evolved from the data intensive, loosely-coupled workloads of the past decade to more tightly coupled ones, wherein ultra-low latency communication is essential for resource disaggregation over the network and to enable emerging programming models.
We introduce Aquila, an experimental datacenter network fabric built with ultra-low latency support as a first-class design goal, while also supporting traditional datacenter traffic. Aquila uses a new Layer 2 cell-based protocol, GNet, an integrated switch, and a custom ASIC with low-latency Remote Memory Access (RMA) capabilities co-designed with GNet. We demonstrate that Aquila is able to achieve under 40 μs tail fabric Round Trip Time (RTT) for IP traffic and sub-10 μs RMA execution time across hundreds of host machines, even in the presence of background throughput-oriented IP traffic. This translates to more than 5x reduction in tail latency for a production quality key-value store running on a prototype Aquila network.
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CliqueMap: Productionizing an RMA-Based Distributed Caching System
Aditya Akella
Amanda Strominger
Arjun Singhvi
Maggie Anderson
Rob Cauble
Thomas F. Wenisch
SIGCOMM 2021 (2021) (to appear)
Preview abstract
Distributed caching is a key component in the design of performant, scalable Internet services, but accessing such caches
via RPC incurs high cost. Remote Memory Access (RMA)
offers a promising, less costly alternative, but achieving a rich
production feature set with RMA-based systems is a significant challenge, as the rich abstraction of RPC lends itself to
solutions for interoperability and upgradeability requirements
of real systems. This work describes CliqueMap, a fully productionized RMA/RPC hybrid serving and caching system,
and the production experience derived from three years of
operation in Google’s datacenters. Building on internal technologies, CliqueMap serves multiple internal product areas
and underlies several end-user-visible services.
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1RMA: Re-Envisioning Remote Memory Access for Multi-Tenant Datacenters
Aditya Akella
Arjun Singhvi
Joel Scherpelz
Monica C Wong-Chan
Moray Mclaren
Prashant Chandra
Rob Cauble
Sean Clark
Simon Sabato
Thomas F. Wenisch
Proceedings of the Annual Conference of the ACM Special Interest Group on Data Communication on the Applications, Technologies, Architectures, and Protocols for Computer Communication, Association for Computing Machinery, New York, NY, USA (2020), 708–721
Preview abstract
Remote Direct Memory Access (RDMA) plays a key role in supporting performance-hungry datacenter applications. However, existing RDMA technologies are ill-suited to multi-tenant datacenters, where applications run at massive scales, tenants require isolation and security, and the workload mix changes over time. Our experiences seeking to operationalize RDMA at scale indicate that these ills are rooted in standard RDMA's basic design attributes: connection-orientedness and complex policies baked into hardware.
We describe a new approach to remote memory access -- One-Shot RMA (1RMA) -- suited to the constraints imposed by our multi-tenant datacenter settings. The 1RMA NIC is connection-free and fixed-function; it treats each RMA operation independently, assisting software by offering fine-grained delay measurements and fast failure notifications. 1RMA software provides operation pacing, congestion control, failure recovery, and inter-operation ordering, when needed. The NIC, deployed in our production datacenters, supports encryption at line rate (100Gbps and 100M ops/sec) with minimal performance/availability disruption for encryption key rotation.
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Achieving Predictable Performance through Better Memory Controller Placement in Many-Core CMPs
Dennis Abts
Natalie Engright Jerger
John Kim
Mikko Lipasti
Proceedings of the International Symposium on Computer Architecture, ACM (2009)
Preview abstract
In the near term, Moore's law will continue to provide an increasing number of transistors and therefore an increasing number of on-chip cores. Limited pin bandwidth prevents the integration of a large number of memory controllers on-chip. With many cores, and few memory controllers, where to locate the memory controllers in the on-chip interconnection fabric becomes an important and as yet unexplored question. In this paper, we show how the location of the memory controllers can reduce contention (hot spots) in the on-chip fabric, as well as lower the variance in reference latency which provides for predictable performance of memory-intensive applications regardless of the processing core on which a thread is scheduled. We explore the design space of on-chip fabrics to find optimal memory controller placement relative to different topologies (i.e. mesh and torus), routing algorithms, and workloads.
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