In SQL Server 2008, each actual CPU
(whether hyperthreaded or physical) has a scheduler created for it when SQL
Server starts.
This is true even if the affinity mask option has been configured
so that SQL Server is set to not use all the available physical CPUs. In SQL
Server 2008, each scheduler is set to either ONLINE or OFFLINE based on the affi
nity mask settings, and the default is
that all schedulers are ONLINE.
Changing the affinity mask value can change the
status of one or more schedulers to OFFLINE, and you can do this without having
to restart your SQL Server.
Note that when a scheduler is switched from ONLINE
to OFFLINE due to a configuration change, any work already assigned to the scheduler
is first completed and no new work is assigned.
