Scale-Out ccNUMA: Exploiting Skew with Strongly Consistent Caching

Vasileios Gavrielatos, Antonios Katsarakis, Arpit Joshi, Nicolai Oswald, Boris Grot, Vijayanand Nagarajan

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract / Description of output

Today’s cloud based online services are underpinned by distributed key-value stores (KVS). Such KVS typically use a scale-out architecture, whereby the dataset is partitioned across a pool of servers, each holding a chunk of the dataset in memory and being responsible for serving queries against the chunk. One important performance bottleneck that a KVS design must address is the load imbalance caused by skewed popularity distributions. Despite recent work on skew mitigation, existing approaches offer only limited benefit for high-throughput in-memory KVS deployments. In this paper, we embrace popularity skew as a performance opportunity. Our insight is that aggressively caching popular items at all nodes of the KVS enables both load balance and high throughput – a combination that has eluded previous approaches. We introduce symmetric caching, wherein every server node is provisioned with a small cache that maintains the most popular objects in the dataset. To ensure consistency across the caches, we use high-throughput fully-distributed consistency protocols. A key result of this work is that strong consistency guarantees
(per-key linearizability) need not compromise on performance. In a 9-node RDMA-based rack and with modest write ratios, our prototype design, dubbed ccKVS, achieves 2.2× the throughput of the state-of-the-art KVS while guaranteeing strong consistency.
Original languageEnglish
Title of host publicationProceedings of the Thirteenth EuroSys Conference
Number of pages15
ISBN (Electronic)978-1-4503-5584-1
Publication statusPublished - 23 Apr 2018
EventEuropean Conference on Computer Systems (EuroSys) - Porto, Portugal
Duration: 23 Apr 201826 Apr 2018


ConferenceEuropean Conference on Computer Systems (EuroSys)
Internet address


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