perfmon "SQLServer:Resource Pool Stats(*)\Query exec memory target (KB)" ties out well with sys.dm_exec_query_resource_semaphores

SELECT opc.[object_name], opc.instance_name, 

       opc.cntr_value AS [Query exec memory target (KB)], 
       SUM(qrs.target_memory_kb) total__target_memory_kb
FROM sys.dm_os_performance_counters opc
JOIN sys.dm_resource_governor_resource_pools rp ON opc.instance_name = rp.[name]
JOIN sys.dm_exec_query_resource_semaphores qrs ON rp.pool_id = qrs.pool_id
WHERE counter_name = 'Query exec memory target (KB)'
GROUP BY rp.pool_id, opc.[object_name], opc.instance_name, opc.cntr_value
ORDER BY rp.pool_id

And the results...