  Real-time scheduling and locking protocols are fundamental facilities to
construct time-critical systems. For parallel real-time tasks, predictable
locking protocols are required when concurrent sub-jobs mutually exclusive
access to shared resources. This paper for the first time studies the
distributed synchronization framework of parallel real-time tasks, where both
tasks and global resources are partitioned to designated processors, and
requests to each global resource are conducted on the processor on which the
resource is partitioned. We extend the Distributed Priority Ceiling Protocol
(DPCP) for parallel tasks under federated scheduling, with which we proved that
a request can be blocked by at most one lower-priority request. We develop task
and resource partitioning heuristics and propose analysis techniques to safely
bound the task response times. Numerical evaluation (with heavy tasks on 8-,
16-, and 32-core processors) indicates that the proposed methods improve the
schedulability significantly compared to the state-of-the-art locking protocols
under federated scheduling.
