Load on my 11g RAC looks like this:
and I don't understand how to get insight into what this "scheduler" wait class is. It seems like "scheduler" that it refers to is the process that runs scheduled maintenance jobs? But can I see which jobs they are? All I see is normal queries waiting for the "scheduler".
The wait even class is "resmgr: cpu quantum"
They are Oracle Resource Manager waits. Resource Manager is a set of Oracle functionality that lets you prioritise work.
See the list of possible waits in the documentation.
It looks like resource manager is in action. Your dba configured this most likely to give certain processes priority over other processes. Oracle Scheduler is fuly integrated with Resource Manager but the way this is presented is a bit misleading. Often it has nothing to do with Scheduled Jobs at all. You can find which sessions are waiting for resource manager by checking v$session:
select sid, serial#, username, resource_consumer_group from v$session
where event like 'resmgr%'
Resource Consumer Group membership of a session determines what priority a session gets. Resource Manager is a very powerful way to manage load on a system to make sure that important processes can finish in their designated time. Maybe your sessions are not mapped to the correct Resource Consumer Group.
Your dba needs good info about business priorities to be able to make a correct Resource Plan.