sql for cpu usage

cpu.sql

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

SELECT TOP ( 30 )
        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 N'%<SystemHealth>%'
                    ) AS x
        ) AS y
ORDER BY record_id DESC ;