On my local system `sysctl kernel.shmmax` prints `kernel.shmmax = 33554432`. 

The Internets tell me the the units for `shmmax` is bytes, and it is the maximum size of a singe shared memory segment. So the above would be 32 MB. However, while testing, I was able to allocate 1GB of SharedArray (internally  it does  a single `shm_open` call that is then `ftruncate` ed to 1GB) - mapped across 5 julia workers, and the shmem was working as required. 

I'll appreciate any explanation for the above.