PARC: A novel OS cache manager

Abstract

To boost input-output performance, operating systems employ a kernelmanaged caching space called the buffer cache or page cache. Given the limited size of a buffer cache, an effective cache manager is required to decide which blocks should be evicted from the cache. Previous cache managers use historical information to make replacement decisions. However, existing approaches are unable to maximize performance since they rely on limited historical information. Motivated by the limitations of existing solutions, this paper proposes a novel manager called the Pattern-assisted Adaptive Recency Caching (PARC) manager. PARC simultaneously uses the historical information of recency, frequency, and access patterns to estimate the locality strengths of blocks and, upon a cache miss, evicts the block with the least strength. Specifically, PARC exploits the reference regularities exhibited in past input-output behaviors to actively and rapidly adapt the recency and frequency information of blocks so as to precisely distinguish blocks with long-and short-term utility. Through comprehensive simulations on a variety of traces of different access patterns, we show that PARC is robust since, except for random workloads where the performance of each cache manager is similar, PARC always outperforms existing solutions. KEYWORDSbuffer cache, cache manager, operating systems, page cache, replacement algorithms Softw Pract Exper. 2018;48:2193-2222. wileyonlinelibrary.com/journal/spe

A New Readahead Framework for SSD-based Caching Storage in IoT Systems

“…Thus, current SSD cache managers adopt a selective caching policy, in which only blocks that are identified as valuable enough are cached into the SSD. That is, they treat the SSD as a by-passable cache to minimize unnecessary writes to the SSD [11][12][13]. Since HDDs exhibit poor performance with random accesses, many SSD cache managers differentiate randomly accessed data from sequentially accessed data and only cache randomly accessed blocks in the SSD.…”

“…Since SSDs and HDDs have different performance models, an SSD cache manager should exploit the complementary properties of SSDs and HDDs. For example, bcache and profit caching differentiate random accesses from sequential accesses and only cache randomly accessed data in SSDs [8,11]. Therefore, data cached in SSDs exhibits different access patterns compared to data stored in HDDs.…”