Taming Tail Latencies in Key-Value Stores under Heterogeneous Workloads
Vikas Jaiman (Université Catholique de Louvain)
Avoiding latency variability in distributed storage systems is challenging. Even in well-provisioned systems, factors such as the contention on shared resources or the unbalanced load between servers affect the latencies of requests and in particular the tail (95th and 99th percentile) of their distribution. This tail latency problem may have a dramatic impact on overall system performance. One effective counter measure for reducing tail latency in key-value stores is to provide efficient replica selection algorithms. However, existing solutions are based on the assumption that all requests have almost the same execution time. This is not true for real workloads. This mismatch leads to increased latencies for requests with short execution time that get scheduled behind requests with large execution times. We propose Héron, a replica selection algorithm that supports workloads with heterogeneous request execution times. We evaluate Héron in a cluster of machines using a synthetic dataset inspired from the Facebook dataset as well as two real datasets from Flickr and WikiMedia. Our results show that Héron outperforms state-of-the-art algorithms by reducing both median and tail latency by up to 41%.
Vikas Jaiman is a research assistant at INGI department at the UCLouvain, Belgium. He is pursuing his PhD from University Grenoble Alpes, France. His research interests include distributed systems particularly focus on the performance of key-value stores. He has published papers in international conferences. He was a part of ACM EuroSys shadow program committee 2018 and Tutorial Chair for EDCC 2018. He is a member of IEEE.
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