Windows – How Can Perfmon % Processor Time Be Over 100%

cpu-usageperfmonsql serversql-server-2005

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%?

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)

Related Solutions

Sql-server – SQL Server suddenly using only a small portion of CPU

Check the sys.dm_os_waiting_tasks and see what the wait resources are. Basically look at the wait_type and see what's in there. Run this query and post the results back.

select wait_type, sum(wait_duration_ms) sum_wait_duration_ms, avg(wait_duration_ms) avg_wait_duration_ms, count(*) waits
from sys.dm_os_waiting_tasks
group by wait_type

You might be suffering from a similar problem to what I talked about this morning on my blog.

Sql-server – SQL Server 2008 CPU usage goes to 100% – troubleshooting help needed

I'd also take a look at sys.dm_os_wait_stats to see what the server is waiting on.

If a few queries are really pegging the CPU like that, I'd suspect lots of parallel execution. It's something to look for.

Best Answer

Related Solutions

Sql-server – SQL Server suddenly using only a small portion of CPU

Sql-server – SQL Server 2008 CPU usage goes to 100% – troubleshooting help needed

Related Topic