SQL Server TempDB Usage and Top Space Consumers

SELECT TOP 20 s.session_id, s.login_name, s.host_name,
       (u.user_objects_alloc_page_count - u.user_objects_dealloc_page_count) * 8 / 1024 AS user_obj_mb,
       (u.internal_objects_alloc_page_count - u.internal_objects_dealloc_page_count) * 8 / 1024 AS internal_obj_mb
FROM sys.dm_db_session_space_usage u
JOIN sys.dm_exec_sessions s ON s.session_id = u.session_id
ORDER BY user_obj_mb + internal_obj_mb DESC;

SELECT SUM(user_object_reserved_page_count) * 8 / 1024 AS user_mb,
       SUM(internal_object_reserved_page_count) * 8 / 1024 AS internal_mb,
       SUM(version_store_reserved_page_count) * 8 / 1024 AS version_store_mb,
       SUM(unallocated_extent_page_count) * 8 / 1024 AS free_mb
FROM tempdb.sys.dm_db_file_space_usage;