DRD will detect the following errors:

• Data races
• Lock contention (deadlocks and delays)
• Misuse of the pthreads API

For the third point, this list of errors detected by DRD, according to its manual, is very similar to that of Helgrind:

• Passing the address of one type of synchronization object (for example, a mutex) to a POSIX API call that expects a pointer to another type of synchronization object (for example, a condition variable)
• Attempt to unlock a mutex that has not been locked
• Attempt to unlock a mutex that was locked by another thread
• Attempt to lock a mutex of type PTHREAD_MUTEX_NORMAL or a spinlock recursively
• Destruction or deallocation of a locked mutex
• Sending a signal to a condition variable while no lock is held on the mutex associated with the condition variable
• Calling pthread_cond_wait on a mutex that is not locked, that is, locked by another thread or that has been locked recursively
• Associating two different mutexes with a condition variable through pthread_cond_wait
• Destruction or deallocation of a condition variable that is being waited upon
• Destruction or deallocation of a locked reader-writer synchronization object
• Attempt to unlock a reader-writer synchronization object that was not locked by the calling thread
• Attempt to recursively lock a reader-writer synchronization object exclusively
• Attempt to pass the address of a user-defined reader-writer synchronization object to a POSIX threads function
• Attempt to pass the address of a POSIX reader-writer synchronization object to one of the annotations for user-defined reader-writer synchronization objects
• Reinitialization of a mutex, condition variable, reader-writer lock, semaphore, or barrier
• Destruction or deallocation of a semaphore or barrier that is being waited upon
• Missing synchronization between barrier wait and barrier destruction
• Exiting a thread without first unlocking the spinlocks, mutexes, or reader-writer synchronization objects that were locked by that thread
• Passing an invalid thread ID to pthread_join or pthread_cancel

As mentioned earlier, helpful here is the fact that DRD also supports detached threads. Whether locking order checks are important depends on one's application.