[tomnipotent]

> There are workloads that will saturate a redis instance's CPU

I might imagine this scenario if you're excessively using smembers and a few other slow ops, but I have yet to see CPU issues outside of bad eval's.

> require finding old keys to delete

LRU/LFU eviction is not particularly CPU intensive.

> redis to do memory defragmentation which can be fairly intensive

Active defrag has relatively negligible overhead, and assuming jemalloc even more so.

[mnutt]

Nothing but lots of small (~100b) pipelined SETs and a small number of GETs here and there. Only 10MB/s but at 100k SETs/sec redis’s CPU core sits at 60-70%. Active defrag can easily send it into a death spiral.