Dealing With High CPU% of SQL Server 2005

Sometimes, we experience performance problem with high CPU% on DB Server. How can we detect which process take most "contribution" to this pheromone step by step?

Step 1. Check if SQL Server Process has problem or not?

 DECLARE @ts_now bigint;  
   SELECT @ts_now = cpu_ticks / CONVERT(float, cpu_ticks_in_ms) FROM sys.dm_os_sys_info   
   SELECT TOP(10) SQLProcessUtilization AS [SQL Server Process CPU Utilization],  
           SystemIdle AS [System Idle Process],  
           100 - SystemIdle - SQLProcessUtilization AS [Other Process CPU Utilization],  
           DATEADD(ms, -1 * (@ts_now - [timestamp]), GETDATE()) AS [Event Time]  
   FROM (  
      SELECT record.value('(./Record/@id)[1]', 'int') AS record_id,  
         record.value('(./Record/SchedulerMonitorEvent/SystemHealth/SystemIdle)[1]', 'int')  
         AS [SystemIdle],  
         record.value('(./Record/SchedulerMonitorEvent/SystemHealth/ProcessUtilization)[1]', 'int')  
         AS [SQLProcessUtilization], [timestamp]  
      FROM (  
         SELECT [timestamp], CONVERT(xml, record) AS [record]  
         FROM sys.dm_os_ring_buffers  
         WHERE ring_buffer_type = N'RING_BUFFER_SCHEDULER_MONITOR'  
         AND record LIKE '%<SystemHealth>%') AS x  
      ) AS y  
 ORDER BY record_id DESC;  

Then you will get result like this:

The picture above shows 70% of CPU% is taking by SQL Server 2005 , not by other processes on DB server.

Step2. Drill down to particular Loginuser and SPID which is taking most of CPU%:

 select  loginame,  *    
 from  master.dbo.sysprocesses  
 where  spid> 50  
 order by cpu desc   

PS: Why "spid > 50" here? Notice that SPIDs 1 to 50 are reserved for internal SQL Server processes, while SPIDs 51 and above are external connections. So most of time we assume that the suspects for High CPU% are from external connections.

Step3: Query the most expensive CPU process by spid (taking spid = 102 for example):

 dbcc inputbuffer(102)   

Then you can start to take further actions for tuning expensive Query or SPs... or just kill the abnormal ones for free :)