What does Large engine mean?

[debajyoti-truefoundry]

foyer/foyer-storage/src/store.rs

Line 347 in 924c126

Large(LargeEngineOptions),

foyer/foyer-storage/src/store.rs

Line 365 in 924c126

pub const OBJECT_SIZE_THRESHOLD: usize = 2048;

What does Large engine exactly mean? Does the cache value need to be at least 2KiB to be eligible for Disk Cache?

[MrCroxx]

Hi. The Large engine means it is suitable for entries that >= 2KiB. But it can also handle entries smaller than it with space amplification. The design aligns with CacheLib.

Moreover, in most cases, I recommend using Large. This is because the concurrency model of Small has a larger performance overhead, and the testing in production is not sufficient.