Finding the CPU usage in SQL Server

SQL Server and system CPU usage history can be obtained from sys.dm_os_ring_buffers using below query

SQL Server 2005

DECLARE @ts_now bigint

SELECT @ts_now = cpu_ticks / CONVERT (float, cpu_ticks_in_ms) FROM sys.dm_os_sys_info

SELECT top 20 record_id, EventTime, 

  CASE WHEN system_cpu_utilization_post_sp2 IS NOT NULL THEN system_cpu_utilization_post_sp2 ELSE system_cpu_utilization_pre_sp2 END AS system_cpu_utilization, 

  CASE WHEN sql_cpu_utilization_post_sp2 IS NOT NULL THEN sql_cpu_utilization_post_sp2 ELSE sql_cpu_utilization_pre_sp2 END AS sql_cpu_utilization

FROM 

(

  SELECT 

    record.value('(Record/@id)[1]', 'int') AS record_id,

    DATEADD (ms, -1 * (@ts_now - [timestamp]), GETDATE()) AS EventTime,

    100-record.value('(Record/SchedulerMonitorEvent/SystemHealth/SystemIdle)[1]', 'int') AS system_cpu_utilization_post_sp2,

    record.value('(Record/SchedulerMonitorEvent/SystemHealth/ProcessUtilization)[1]', 'int') AS sql_cpu_utilization_post_sp2 , 

    100-record.value('(Record/SchedluerMonitorEvent/SystemHealth/SystemIdle)[1]', 'int') AS system_cpu_utilization_pre_sp2,

    record.value('(Record/SchedluerMonitorEvent/SystemHealth/ProcessUtilization)[1]', 'int') AS sql_cpu_utilization_pre_sp2

  FROM (

    SELECT timestamp, CONVERT (xml, record) AS record 

    FROM sys.dm_os_ring_buffers 

    WHERE ring_buffer_type = 'RING_BUFFER_SCHEDULER_MONITOR'

      AND record LIKE '%%') AS t

) AS t

ORDER BY record_id desc

SQL Server 2008

DECLARE @ts_now bigint

SELECT @ts_now = cpu_ticks / (cpu_ticks/ms_ticks)  FROM sys.dm_os_sys_info

SELECT top 20 record_id, EventTime, 

  CASE WHEN system_cpu_utilization_post_sp2 IS NOT NULL THEN system_cpu_utilization_post_sp2 ELSE system_cpu_utilization_pre_sp2 END AS system_cpu_utilization, 

  CASE WHEN sql_cpu_utilization_post_sp2 IS NOT NULL THEN sql_cpu_utilization_post_sp2 ELSE sql_cpu_utilization_pre_sp2 END AS sql_cpu_utilization

FROM 

(

  SELECT 

    record.value('(Record/@id)[1]', 'int') AS record_id,

    DATEADD (ms, -1 * (@ts_now - [timestamp]), GETDATE()) AS EventTime,

    100-record.value('(Record/SchedulerMonitorEvent/SystemHealth/SystemIdle)[1]', 'int') AS system_cpu_utilization_post_sp2,

    record.value('(Record/SchedulerMonitorEvent/SystemHealth/ProcessUtilization)[1]', 'int') AS sql_cpu_utilization_post_sp2 , 

    100-record.value('(Record/SchedluerMonitorEvent/SystemHealth/SystemIdle)[1]', 'int') AS system_cpu_utilization_pre_sp2,

    record.value('(Record/SchedluerMonitorEvent/SystemHealth/ProcessUtilization)[1]', 'int') AS sql_cpu_utilization_pre_sp2

  FROM (

    SELECT timestamp, CONVERT (xml, record) AS record 

    FROM sys.dm_os_ring_buffers 

    WHERE ring_buffer_type = 'RING_BUFFER_SCHEDULER_MONITOR'

      AND record LIKE '%%') AS t

) AS t

ORDER BY record_id desc