CPU vs. Duration in SQL Server Profiler

Question

On this article, I am reading that:

Data column	Column Number	Description
Duration	13	Amount of time (in milliseconds) taken by the event.
CPU	18	Amount of CPU time (in milliseconds) used by the event.

I am troubleshooting a query that's using

• CPU: 2,650 ms
• Duration: 733 ms

Shouldn't these numbers be somewhat closer together? How can the query use more CPU time than the entire duration of the event?

Thanks

Answer 1

What is most likely happenings is that your SQL server is splitting your SELECT statement up to run on multiple threads on your Multi-core CPU. Judging by the times returned, I would venture to guess you have a Quad-Core CPU in your server.

For instance: If CPU1, Cpu2, and CPU3 all take 750ms and CPU4 takes 400ms, then you would have a combined total of 2650ms, but an overall duration of only 750ms.