Under Sybase, you can query the MDA table monProcessWaits (actually a pseudo table mapped to output from a stored procedure) for cumulative waits and types per spid. So I can query this table every 5 seconds, for example, and calculate by subtracting current waits from previous waits and current time waited minus previous time waited how long a given spid waited in the period, the type of waits and wait time for each type. This is a powerful capability especially when the wait data can be correlated with other events that have occurred such as slow stored procedures.
The same capability does not seem to exist in Sql Server. The closest thing seems to be sys.dm_os_waiting_tasks which gives you spids that are waiting at a point in time, what they are waiting for, how long they've been waiting, etc. Am I missing anything?
If I were to run sys.dm_os_waiting_tasks every 3 seconds against an Sql Server database from a connected node would I be putting any significant load on the Sql Server instance?