We are experiencing what is for us a serious issue... With an upgrade to SQL Server 2008 R2 (SP2) running on a new Dell 12th generation Poweredge 820 server with Windows Server 2008 R2 Enterprise, the precision of SYSDATETIME has dropped to every 15.6 milliseconds. It previously (SQL 2008) was accurate to approximately 1 millisecond.
A query to sys.dm_os_sys_info shows that the time source is "QUERY_PERFORMANCE_COUNTER" - my understanding is that the interval should be less than 600 cycles. It is also my understanding that SQL Server 2008 R2 is now supposed to choose the most precise time source "automatically" - herein lies what I believe is the bug - because our precision is only 15.6 milliseconds after the upgrade.
I see that by using trace flag 8049 we can force the database to use the "Multi Media" counter, which will return us to that 1 millisecond level of precision - this will be our attempted workaround if we cannot get the database to choose the most accurate time source.
A simple script that selects GetDate() and SysDateTime() in a loop shows GetDate() stepping every 3.3 milliseconds, and SysDateTime() stepping every 15.6 milliseconds.
Any feedback or solutions other than using trace 8049 would be greatly appreciated!