BOL: Returns information about all latch waits organized by class.
The latch equivalent to sys.dm_os_wait_stats. There are in the region of 120 different latch types, BOL provides a brief description for each of them. The counters can be reset using DBCC SQLPERF ('sys.dm_os_latch_stats', CLEAR). The counters do not track latch requests that succeed or fail without a wait.