Comment 7 for bug 246413

I am also experiencing this on a brand new 9.04 64-bit server installation on a very capable machine (Xeon 5520, 8GB RAM, HP SA RAID controller).

With one thread writing to the encrypted volume the system slows down with 2 kcryptd threads at 50-75% and ~6.00 load.
With two threads writing to the encrypted volume the system becomes nearly completely unresponsive with a load average around 15-16.

Re-nicing the kcryptd threads to 0 (changed from -5) makes the system much more responsive but does not improve read/write speeds at all.

I'm getting read speeds around 20MB/s under load, 40MB/s when idle. I'm seeing reads at over 200MB/s on the unencrypted portions of the volume.