FlashPage: A read cache for low-latency SSDs in web proxy servers

Abstract

The paper introduces FlashPage, a high-speed SSD caching system designed for ultra -fast media, with the of enhancing web page delivery in proxy servers. Traditional SSD caching schemes, designed primarily for HDD-based primary storage, encounter difficulties when applied to capacity -class SSDs as primary storage. This limits the high-performance capabilities of caching media. To address this issue, FlashPage operates within the Linux virtual filesystem layer, shortening the hit -handling path and minimizing lookup overhead. incorporates a compact radix tree to fast locate cached data. These approaches reduce the software overhead for a 4kB read hit by over 5 times. FlashPage also employs novel admission and eviction policies to minimize flash wear while maintaining a high hit rate. As a second -level storage cache, FlashPage predicts the hotness of potential demotion candidates in the first -level storage cache (i.e., page cache), achieving a 10.1% higher hit rate and reducing write traffic by 10.4% compared to LRU. Evaluations using Varnish and Squid caches show its effectiveness, with up to 29.6% and 38.2% faster web request processing compared to Bcache and DM -Cache, state-of-the-art caching schemes in mainline Linux kernels.