Why does an I/O storm cause a mq_send (without a mq_receive waiting) to stall?
Using 2.6.27, 2.6.33.9 RT, highmem_is_dirtyable = 1, 8gig, no swap, 1 Real time multi-process, muti-thread app which waits on semaphores prior to doing any mq_receives.
a few dd bs=27M count=1 ..... will stall any processes trying to do an mq_send.

I know the disk throughput is very bad 22.9MB/s (R), 18.4 MB/s (W) when using oflag=direct but I don't see where an mq_send would write onto the drive.