I recently released some RAID testing I did using the sysbench testing framework.  In light of the recent attention paid to multi-core CPU scalability, I have been working on some related tests trying to identify sources of contention using that same set of tests.

I've been doing some benchmarking recently to satisfy the curiosity about 5.1's performance compared with 4.1.  The major question this time revolves around how much additional performance an external RAID array can provide (for us it's typically beyond the 6 drives a Dell 2950 can hold). 

There's been a lot of rumors floating around internally at Yahoo that it's best to turn off some of your CPU cores when using Innodb, especially if you have a machine with > 4 cores.  At this point there's no question in my mind that Innodb doesn't perform much better when you double your cores from 4 to 8, but I really wanted to know if 8 actually performed worse.