Comment 37 for bug 82528

Extremely annoying bug, happend with hardy, intrepid and jaunty.

Current Configuration:
 - Jaunty x64
 - Intel(R) Core(TM)2 Duo CPU T7300 @ 2.00GHz, 4GiB DDR2
 - Encrypted Home (--cipher aes-xts-plain --key-size 256)
 - kernel.org custom 2.6.30 kernel

I simulate a write load (like copying large files):
while [ true ]; do dd if=/dev/zero of=dummy bs=1M count=4K; sync; rm dummy; sync; done
(sync to force ext4's delayed allocation to write out the blocks)

and now the system is extremely unresponsive.
Doing a simple `ls` takes over 10s, the cursor hangs, etc.
It looks like the reads to the disk arent get
Maybe interesting: iostat shows around 200,000 tps for the dm-5 device while less than 100 tps for the /dev/sda device.

In the next days I'll try to get more information about what causes the problem, checking different ciphers and block sizes, fiddling with the scheduler, etc. Renicing kcryptd didn't help.