Comment 140 for bug 620074

On my machine (nForce 5, AMD Phenom II 940) I also experience huge slowdowns when performing I/O. For example, using Ben's:
dd if=/dev/zero of=/tmp/test bs=1M count=1M
test, it takes me about 40 secs to spawn a shell (15 secs for konsole to open a new tab, and about 25 secs for the shell to actually spawn). This was conducted on my a HD with ext4. Turning off swap helps a lot with launching a shell.

On a more substantial note, I use Unison to sync files between various places and when it is running my system is hardly responsive. This happens to me on ext4, ext3, and ReiserFS.

Changing the schedule to noop, the dd-and-open-shell test is very responsive (with both swapon or off), but any substantial usage, such as using firefox is still slow, just as it is above with cfq.

If I can free up some space and one of my partitions, I'm going to install some distro pre 2.6.18 and "feel" what the performance is like.