Hardware-Accelerated Kernel-Space Memory Compression Using Intel QAT

Data compression has been widely used by datacenters to decrease the consumption of not only the memory and storage capacity but also the interconnect bandwidth. Nonetheless, the CPU cycles consumed for data compression notably contribute to the overall datacenter taxes. To provide a cost-efficient data compression capability for datacenters, Intel has introduced QuickAssist Technology (QAT), a PCIe-attached data-compression accelerator. In this work, we first comprehensively evaluate the compression/decompression performance of the latest on-chip QAT accelerator and then compare it with that of the previous-generation off-chip QAT accelerator. Subsequently, as a compelling application for QAT, we take a Linux memory optimization kernel feature: compressed cache for swap pages (zswap), re-implement it to use QAT efficiently, and then compare the performance of QAT-based zswap with that of CPU-based zswap. Our evaluation shows that the deployment of CPU-based zswap increases the tail latency of a co-running latency-sensitive application, Redis by 3.2-12.1×, while that of QAT-based zswap does not notably increase the tail latency compared to no deployment of zswap.