SQL Clone
SQLServerCentral is supported by Redgate
 
Log in  ::  Register  ::  Not logged in
 
 
 


Cores not being used on Windows 2008 SQL Server 2012


Cores not being used on Windows 2008 SQL Server 2012

Author
Message
ychen1214
ychen1214
Forum Newbie
Forum Newbie (7 reputation)Forum Newbie (7 reputation)Forum Newbie (7 reputation)Forum Newbie (7 reputation)Forum Newbie (7 reputation)Forum Newbie (7 reputation)Forum Newbie (7 reputation)Forum Newbie (7 reputation)

Group: General Forum Members
Points: 7 Visits: 26
Hi,

I am experiencing instances where not all the cores are being utilize for certain queries in SQL Server 2012.

When this happens one of the cores becomes max to 100% CPU usage. This causes everything on the server to slow down and no one else can use the sql server until the offending query is kill from the server. My guess is that it is related to parallelism.

Any suggestions on how to go about debugging this? I can't see the actual execution plan because we always end up killing the offending query. It is a production machine so I can't really play around with it.



Thanks,
Tommy Bollhofer
Tommy Bollhofer
SSCommitted
SSCommitted (1.8K reputation)SSCommitted (1.8K reputation)SSCommitted (1.8K reputation)SSCommitted (1.8K reputation)SSCommitted (1.8K reputation)SSCommitted (1.8K reputation)SSCommitted (1.8K reputation)SSCommitted (1.8K reputation)

Group: General Forum Members
Points: 1818 Visits: 3359
Which edition are you using? Are you aware of the new core licensing model in SQL Server 2012?

http://www.microsoft.com/en-us/sqlserver/get-sql-server/how-to-buy.aspx

http://sqlblog.com/blogs/aaron_bertrand/archive/2012/04/27/a-cautionary-tale-about-grandfathering-CAL-licenses-in-SQL-Server-2012-Enterprise.aspx

http://www.sqlbeats.com/?p=13

Tommy

Follow @sqlscribe
Grant Fritchey
Grant Fritchey
SSC-Forever
SSC-Forever (41K reputation)SSC-Forever (41K reputation)SSC-Forever (41K reputation)SSC-Forever (41K reputation)SSC-Forever (41K reputation)SSC-Forever (41K reputation)SSC-Forever (41K reputation)SSC-Forever (41K reputation)

Group: General Forum Members
Points: 41133 Visits: 32666
You don't need to see the actual plan to see if it's doing a parallel execution. You can pull the plan out of cache for the query, while it's running. That will show you everything you need to know if it's a parallelism problem or not. Use sys.dm_exec_requests and join that to sys.dm_exec_query_plan.

But, if it's one CPU and not the others, it sounds like it's more likely to be something other than a parallel execution. Maybe you do need it. I would check the Max Degree of Parallelism setting on the server first. See if it's set to anything other than 0 (the default), especially if it's set to 1. I would also check the affinity masking on the CPUs and how many CPUs SQL Server can see. I'd also check the cost threshold for parallelism. The default is 5, but that's usually very low for most systems.

----------------------------------------------------
The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood...
Theodore Roosevelt

The Scary DBA
Author of: SQL Server Query Performance Tuning and SQL Server Execution Plans
Product Evangelist for Red Gate Software
Go


Permissions

You can't post new topics.
You can't post topic replies.
You can't post new polls.
You can't post replies to polls.
You can't edit your own topics.
You can't delete your own topics.
You can't edit other topics.
You can't delete other topics.
You can't edit your own posts.
You can't edit other posts.
You can't delete your own posts.
You can't delete other posts.
You can't post events.
You can't edit your own events.
You can't edit other events.
You can't delete your own events.
You can't delete other events.
You can't send private messages.
You can't send emails.
You can read topics.
You can't vote in polls.
You can't upload attachments.
You can download attachments.
You can't post HTML code.
You can't edit HTML code.
You can't post IFCode.
You can't post JavaScript.
You can post emoticons.
You can't post or upload images.

Select a forum

































































































































































SQLServerCentral


Search