dclemens (7/5/2016)
I want 8 files because I have 8 CPUs.
8 CPUs doesn't mean 8 files for TempDB.
Using this query, I'm showing avg_write_stall_ms >280ms, which seems very high to me.
Adding files won't help with that. Adding extra files is for allocation contention (page latch waits on the allocation pages in TempDB). If you have IO contention (high stalls, slow IO, etc), then you either need to move the TempDB files to faster storage, or move half of them to a separate IO subsystem.
The one thing you do need to do is make all four TempDB data files the same size.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability