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 SQL Server Administration (2012)
 SQL using 8 CPUs out of 32
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yelouati
Starting Member

10 Posts

Posted - 08/23/2013 :  20:26:53  Show Profile  Reply with Quote
Hi All,

I am in a bit of a pickles. During a load test I discovered that SQL was using 8 CPUs (100%) while not using the other 24.
The 8 CPUs belong to the same NUMA node.
This is SQL 2012 SP1 (3000).
Interestingly, if within Windows (NOT PROCESSOR AFFINITY MASK in SQL) I set the affinity to more CPUs, it takes them and the transaction times drop significantly.
Since the concurrent running code is the same SP, I am guessing SQL is using processors closer to the memory map. But how clumsy.
Anyone has any ideas how I can make use of all CPUs?

Thanks

yelouati
Starting Member

10 Posts

Posted - 08/25/2013 :  14:57:59  Show Profile  Reply with Quote
I made progress on this issue-

This is a numa related issue.

Either follow
http://blogs.msdn.com/b/psssql/archive/2011/09/01/sql-server-2008-2008-r2-on-newer-machines-with-more-than-8-cpus-presented-per-numa-node-may-need-trace-flag-8048.aspx

Or disable interleaved nodes in the BIOS.

Please note sql 2012 SP1 CU3 fixes some of these issues.

Yassine Elouati
Consulting DBA
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