Uneven usage of CPUs in SQL 2005 environment: some CPUs consistently busier than others

  • We have a SQL-2005 instance (standard edition, 32-bit) on a VM server (Windows 2003 R2) consisting of 8 logical CPUs.

    The SQL instance has detected all CPUs and I have not made any adjustments to any default settings (CPU mask etc.);

    however, the workload distribution as I see it in Task Manager is quite uneven: the first 4 CPUs are a lot busier than the last 4.

    What could be the reason for this? Anyone seen this before?

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    SQL Server 2016 Columnstore Index Enhancements - System Views for Disk-Based Tables[/url]
    Persisting SQL Server Index-Usage Statistics with MERGE[/url]
    Turbocharge Your Database Maintenance With Service Broker: Part 2[/url]

  • Any thoughts anyone?

    __________________________________________________________________________________
    SQL Server 2016 Columnstore Index Enhancements - System Views for Disk-Based Tables[/url]
    Persisting SQL Server Index-Usage Statistics with MERGE[/url]
    Turbocharge Your Database Maintenance With Service Broker: Part 2[/url]

  • My guess would be that it's normal. The process by which the multiprocessor uses it's available cores is quite complex (I won't even pretend to know)

    But I would assume it's ok.

    On a related note. I've seen this behavior in my past as well.

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  • Jason Selburg (3/18/2011)


    My guess would be that it's normal. The process by which the multiprocessor uses it's available cores is quite complex (I won't even pretend to know)

    But I would assume it's ok.

    On a related note. I've seen this behavior in my past as well.

    Thank you for replying.

    Yes, I also think this must be normal. In the SQL ERRORLOG, upon starting, it is stated that 8 CPUs have been detected. Also, in SSMS under properties for the instance I see that 8 cpus are shown. So the SQL instance is aware that there are 8 cpus on the server, and I haven't changed any of the default settings for this.

    We are trying to troubleshoot a server performance issue, and our system admins are pestering me as to why the SQL instance is not using all the cpus.

    When something is wrong, it's got to be the SQL's fault... (sarcasm 😉 )

    Anyway, I've seen a few other occurences of this reported on the web, and everyone appears to think it is normal behavior.

    Thanks again!

    __________________________________________________________________________________
    SQL Server 2016 Columnstore Index Enhancements - System Views for Disk-Based Tables[/url]
    Persisting SQL Server Index-Usage Statistics with MERGE[/url]
    Turbocharge Your Database Maintenance With Service Broker: Part 2[/url]

  • It could also be how you have your virtual server set up. Make sure you're following best practices as recommended by Microsoft and your VM vendor for SQL Server virtual machines. They have some unique needs.

  • Pam Brisjar (3/18/2011)


    It could also be how you have your virtual server set up. Make sure you're following best practices as recommended by Microsoft and your VM vendor for SQL Server virtual machines. They have some unique needs.

    Don't I know it?

    Unfortunately, on this topic I'm at the mercy of the sysadmins, and I can only hope they've done their due diligence.

    Thanks,

    Marios

    __________________________________________________________________________________
    SQL Server 2016 Columnstore Index Enhancements - System Views for Disk-Based Tables[/url]
    Persisting SQL Server Index-Usage Statistics with MERGE[/url]
    Turbocharge Your Database Maintenance With Service Broker: Part 2[/url]

  • I hear you. Had to fight some of those battles myself. But make sure you're doing your due diligence and at least presenting the information to the sysadmins (and perhaps their managers) so that it's out there and available.

    We had a huge production performance issue just a few months ago that was solved as soon as the sysadmins listened to me and set up the SQL Server VM environment the way I told them it should be.

  • Pam Brisjar (3/18/2011)


    I hear you. Had to fight some of those battles myself. But make sure you're doing your due diligence and at least presenting the information to the sysadmins (and perhaps their managers) so that it's out there and available.

    We had a huge production performance issue just a few months ago that was solved as soon as the sysadmins listened to me and set up the SQL Server VM environment the way I told them it should be.

    Thank you, can you provide any pointers on this?

    I'll admit almost complete ignorance on how to best set up a VM environment for SQL.

    Much appreciated!

    __________________________________________________________________________________
    SQL Server 2016 Columnstore Index Enhancements - System Views for Disk-Based Tables[/url]
    Persisting SQL Server Index-Usage Statistics with MERGE[/url]
    Turbocharge Your Database Maintenance With Service Broker: Part 2[/url]

  • Thanks again!

    __________________________________________________________________________________
    SQL Server 2016 Columnstore Index Enhancements - System Views for Disk-Based Tables[/url]
    Persisting SQL Server Index-Usage Statistics with MERGE[/url]
    Turbocharge Your Database Maintenance With Service Broker: Part 2[/url]

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