DBCC SQL Perf :

DBCC SQL Perf function is used for the following purposes,
1. To list down the percentage of log file used.
2. Clear the OS waits information (sys.dm_os_wait_stats)
3. Clear the Latch waits information ( sys.dm_os_latch_stats )

Considering the database VenkatDB is having 1 MB for the log file,
DBCC SQLPERF(LOGSPACE)
-- This command is used to list down the spaces available for the database + How much % of log file is used + status of the log file(either its available and working or not) - 0 indicates, there is no potenition issue with the database.


Clearing OS wait/Latch statistics:
Below is the command to clear all the statistics collected for OS wait and Latch wait.

DBCC SQLPERF("sys.dm_os_wait_stats",CLEAR);
DBCC SQLPERF("sys.dm_os_latch_stats ",CLEAR);

Cheers,
Venkatesan Prabu .J
http://venkattechnicalblog.blogspot.com/