Comment 104 for bug 131094

The ppa kernel does not fix the problem. It is only delayed. I have made some tests on a fresh hardy installation with the kernel Ubuntu 2.6.20-15.27-generic (feisty repository), Ubuntu 2.6.24-17.31-generic and Ubuntu 2.6.25-1.2ubuntu6-generic. I always restarted the system and started the tests directly after the login. To simulate a disc intensive application, I copied eight 1GB files from /dev/zero to the harddisk. It has a similar behavior as working with vmware and eclipse.
Every application was started only once on every tests (there was always a reboot between two gimp tests or two firefox tests). Sometimes it takes a lot of time to browse to /usr/share/backgrounds and to open a image or to select an tool under the 24 and 25 kernel. And I have to wait 5s - 10s after every mouse action. But this behavior is not deterministic, and occurs only every second or third test. You can see it on the firefox test.

Has someone recognized the poor desktop responsiveness on a SCSI-System?

And I don't think, that this problem is caused by the kernel only, because the desktop freezes occurs with the feisty kernel under hardy too. Perhaps something with xorg or gnome?

test results:

kernel
20 / 24 / 25

start gimp at load avg 6
10s / 30s / 30s

start gimp at load avg 8
10s / 23s / 40s

start firefox at load avg 10
17s / 44s / 44s
load four pages (saved session) after start
7s / 27s / 22s

start firefox as load avg 14
15s / 20s / 60s
load four pages (saved session) after start
7s / 20s / 20s

starting oowriter at load avg 12
15s / 20s / 40s