Since Redis 6 supports multi-threaded IO, does it make sense to deploy Redis on machines with more than 2 cores? Will it be able to take advantage of the additional cores or are 2 cores still ideal(one for the main thread, and the other to handle bgsave and other housekeeping operations)?
Similarly, on AWS ElastiCache does it make sense to use instance types with >2 vCPUs?
Basing on release notes, I guess it does. Here's a piece of small information from there:
Despite Redis’ well-deserved reputation for high performance, its single-threaded architecture has been controversial among engineers who wondered if Redis could be even faster. Redis 6 rings in a new era: while it retains a core single-threaded data-access interface, I/O is now threaded.
By delegating the time spent reading and writing to I/O sockets over to other threads, the Redis process can devote more cycles to manipulating, storing, and retrieving data—boosting overall performance. This improvement retains the transactional characteristics of previous versions, so you don’t have to rethink your applications to take advantage of the increased performance. Similarly, Redis’ single-threaded DEL command can now be configured to behave like the multi-thread UNLINK command that has been available since Redis version 4.
The performance of a local variable is almost always unbeatable, Finally, even a database as high performance as Redis will be much slower than accessing something from the stack or heap. Redis 6 adds a new technique for sophisticated client libraries to implement a client-side caching layer to store a subset of data in your own process. This implementation is smart enough to manage multiple updates to the same data and keep your data as in-sync as possible—while retaining the advantages of Redis with the speed of local variables.
You could also check/compare it with redis-benchmark or memtier harness for your instance/workload profile.
