Barry,

I'm suspicious there might be more to the performance issue than just the ecryptfs overhead.  While experimenting with a read benchmark, I just happened to notice that when reading from an ecryptfs filesystem, the CPU usage is unusually high in the *python3* process.

For example:

./benchmark.py /home/.dmedia
  => 149 MB per second
  => top shows 22-24% CPU usage

./benchmark.py /home/jderose/.dmedia
  => 38.9 MB per second
  => top shows 79-85% CPU usage

It's the same physical drive in both cases, but the one in /home/jderose is ecryptfs.  If it was just ecryptfs overhead, wouldn't there be lower CPU utilization in the python3 process, as there would be a lower throughput coming from the kernel, more time waiting on IO?

In both cases, there were 56 files, for a total of 19.5 GB.  I ran this on 64-bit Ubuntu Oneiric, Python 3.2.2.

Here's the benchmark:

http://bazaar.launchpad.net/~jderose/filestore/multi/view/head:/benchmark.py