Random notes on improving the Redis LRU algorithm

Re:Random notes on improving the Redis LRU algorithm by bentorfs on Friday July 29, 2016 @10:08AM (#12186887)

> The pseudo-LRU redis used to have is appropriate for very high-speed caches (it's essentially a 5-way associative cache), but is so very not appropriate when going out to disk, where the access latency is horrible.

Redis is an in-memory database, so what's the problem?

Also, keep in mind that it has to fit in 24 bits, so not all solutions are possible, even if they are theoretically better

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Re:Random notes on improving the Redis LRU algorithm by onetwotree on Friday July 29, 2016 @02:42PM (#12188946)

It's possible that he refers to a cache miss "going out to disk" by requiring a read from a different data store (a SQL database, for example).

But this is really kind of silly - the entire idea with caching is that misses are much slower than hits. The statement is something like "you need a stupid good cache because misses hurt". Software engineering is always about tradeoffs, and antirez does a fantastic job of describing them in this post.

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