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I am somewhat of an accidental DBA, and I'm troubleshooting a SQL Server box where performance has been notoriously poor (as reported by the customer). I was not involved in the initial planning of this job - so I am learning more about this machine as I go.

Motivated by Brent Ozar's talk on SQL Server and Perfmon, I saw this as a good starting point. I just started logging the Perfmon data to csv yesterday - so I have about 24 hours of 30 second samples. I decided to start "slicing and dicing" the data!

I decided to look for any CPU bottlenecks first.

The machine is running: Intel(R) Xeon(R) CPU E5-2420 0 @ 1.90GHz, 1900 Mhz, 6 Core(s), 12 Logical Processor(s)

I launched CPUz and noticed that the each of the 6 cores was actually operating at a throttled back frequency of 1.1GHz. I have adjusted the Windows power plan settings from balanced to high performance, but it didn't seem to make a difference. I believe the BIOS may be overriding this. I will have to check...

Anyways, on to the Perfmon data...

Looking at the Processor(x)\% Processor Time counters (where x is in [0-11]), I noticed that for Processor (2), the utilization is consistently twice the average of the others. Processor (2) had an average of 56%, while Processors (1) and (3) had averages of 14% and 11%, respectively. The max for Processor (2) topped out at 97%. The max for the others barely reached 50%. This is definitely unbalanced, but why? And should I be concerned?

For reference, the Processor Queue length averaged 0.2, with a max of 11.

  1. Should this unbalanced % Processor Time be a concern? Or am I getting upset over nothing?
  2. If this is something I need to explore further, where should I start? Is there a good way to track processor affinity and see what's causing Processor (2) to run consistently high?

Any help would be appreciated.

John Russell
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1 Answers1

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  1. This is not of any concern. I believe there are optimizations so that the same CPU may be assigned to a particular process so that the CPU memory cache can continue to be used.
  2. Do you have Multi-Threading enabled on the BIOS? This basically makes double the number of physical CPU cores visible but these cores are slower than the primary cores. You might try disabling this feature if indeed you are using it.
mdpc
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