Abstract | ||
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ABSTRACTMany social-media and IoT services have very large working sets consisting of billions of tiny (≈100 B) objects. Large, flash-based caches are important to serving these working sets at acceptable monetary cost. However, caching tiny objects on flash is challenging for two reasons: (i) SSDs can read/write data only in multi-KB "pages" that are much larger than a single object, stressing the limited number of times flash can be written; and (ii) very few bits per cached object can be kept in DRAM without losing flash's cost advantage. Unfortunately, existing flash-cache designs fall short of addressing these challenges: write-optimized designs require too much DRAM, and DRAM-optimized designs require too many flash writes. We present Kangaroo, a new flash-cache design that optimizes both DRAM usage and flash writes to maximize cache performance while minimizing cost. Kangaroo combines a large, set-associative cache with a small, log-structured cache. The set-associative cache requires minimal DRAM, while the log-structured cache minimizes Kangaroo's flash writes. Experiments using traces from Facebook and Twitter show that Kangaroo achieves DRAM usage close to the best prior DRAM-optimized design, flash writes close to the best prior write-optimized design, and miss ratios better than both. Kangaroo's design is Pareto-optimal across a range of allowed write rates, DRAM sizes, and flash sizes, reducing misses by 29% over the state of the art. These results are corroborated with a test deployment of Kangaroo in a production flash cache at Facebook. |
Year | DOI | Venue |
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2021 | 10.1145/3477132.3483568 | SOSP |
DocType | Citations | PageRank |
Conference | 0 | 0.34 |
References | Authors | |
0 | 9 |
Name | Order | Citations | PageRank |
---|---|---|---|
Sara McAllister | 1 | 1 | 1.36 |
Benjamin W Berg | 2 | 8 | 4.24 |
Julian Tutuncu-Macias | 3 | 0 | 0.34 |
Juncheng Yang | 4 | 8 | 3.14 |
Sathya Gunasekar | 5 | 0 | 0.34 |
Jimmy Lu | 6 | 1 | 1.07 |
Daniel F. Berger | 7 | 6 | 3.39 |
Nathan Beckmann | 8 | 352 | 19.46 |
Gregory R. Ganger | 9 | 4560 | 383.16 |