[GRASS-user] GRASS 7 Bottleneck

[Seth Price]

I'm running a few instances of GRASS, and I've hit an extreme bottleneck. The problem is that I can't figure out what it is.

I have a module that I wrote in the GRASS 7.0 environment that should be I/O bound. It normally takes about 10 minutes to finish running. I have seven instances running from one disk, and each one is taking on the order of 10 hours to finish. Why?

NOTE:
- The processes aren't I/O bound. 'iostat' lists a constant 30 MB/s transfer rate. It should be able to handle twice that. The transfers per second are < 100, and I've seen it handle triple that (at 60 MB/s).
- The load average is currently below 1. I have 16 processors, so CPU shouldn't be a problem.
- I have 16 GB of RAM, and it's full, but not thrashing.

If it's not I/O, CPU, or RAM, then what is it slowing GRASS?
Thanks,
Seth