Is ity possible to find how many processors SQL server is using ? What is HIDDEN ONLINE  mean ?

Posted on 2014-08-20
Last Modified: 2014-08-20
When I execute this below Query I got the following output.   It saying 3 of them are VISIBLE ONLINE and remaining two  it saying HIDDEN ONLINE. Does SQL server uses the Hidden CPUs ?

select  scheduler_id,cpu_id, status, is_online from sys.dm_os_schedulers

scheduler_id      cpu_id      status                                 is_online
0                       0            VISIBLE ONLINE                   1
1                       1           VISIBLE ONLINE                   1
1048578               0           HIDDEN ONLINE                    1
1048579               1           HIDDEN ONLINE                   1
1048576               0           VISIBLE ONLINE (DAC)           1
Question by:Varshini S
    LVL 22

    Assisted Solution

    by:Steve Wales
    The valid values for this view are all defined in the documentation:

    HIDDEN means that they are reserved for system requests.
    VISIBLE means they are available for user requests.
    LVL 44

    Accepted Solution

    From MSDN


    Indicates the status of the scheduler. Can be one of the following values:







    Is not nullable.

    HIDDEN schedulers are used to process requests that are internal to the Database Engine. VISIBLE schedulers are used to process user requests.

    OFFLINE schedulers map to processors that are offline in the affinity mask and are, therefore, not being used to process any requests. ONLINE schedulers map to processors that are online in the affinity mask and are available to process threads.

    DAC indicates the scheduler is running under a dedicated administrator connection.

    HOT ADDED indicates the schedulers were added in response to a hot add CPU event."
    LVL 44

    Expert Comment

    by:Vitor Montalvão
    But for knowing how many CPU's there's a simple query for that:

    select cpu_count from sys.dm_os_sys_info 

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