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Bill Paetzke
Asked: 2010-05-19 17:01:39 +0800 CST

How can a Perfmon "% Processor Time" counter be over 100%?

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The counter, Process(sqlservr)\% Processor Time, is hovering around 300% on one of my database servers. This counter reflects the percent of total time SQL Server spent running on CPU (user mode + privilege mode). The book, Sql Server 2008 Internals and Troubleshooting, says that anything greater than 80% is a problem.

How is it possible for that counter to be over 100%?

sql-server sql-server-2005 perfmon cpu-usage

2 Answers

  1. Best Answer

    There are two counters with the same name:

    Process\% Processor Time: The sum of processor time on each processor

    Processor(_Total)\% Processor Time: The total for all processors

    Your question indicates you're using the first counter, which means that its maximum value is 100% * (no of CPUs).

    So if you have 4 CPUs, then the total maximum is 400%, and 80% is actually (400 * 0.8 =) 320% (and for 8 CPUs it's 640%, etc etc)

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  2. This value is calculated over the base line of (No of Logical CPUS * 100), So this is going to be a calculated over a baselin of more than 100.

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