Some background information on the SQL Schedulers, will make understanding the RUNNABLE – SUSPENDED – RUNNING model clearer.

Schedulers are made up of three parts. A thread cycles though these three parts

1) Processor

2) Waiter list – threads waiting for resources. Use Sys.dm_os_waiting_tasks to view resource waits for the resources

3) Runnable – thread has all the resources and waiting for the processor. Explore runnable status with

the sys.dm_os_schedulers and sys.dm_exec_requests DMVs

This leads us into the RUNNABLE – SUSPENDED – RUNNING

1) RUNNING – thread is executing on the server

2) SUSPENDED – thread is waiting for resources to become available.

3) RUNNABLE – the thread is waiting to execute on the processor