Comment 205 for bug 620074

(In reply to comment #16)
> I tried elevator=as on my system, and it did not change the behaviour.
> Copying
> files from external USB to internal encrypted SSD still totally smashes
> interactive performance. So this issue might be unrelated.
>

Note, some SSD's have very poor random-write performance, this can cause stuttering and all sorts of side effects. Anandtech investigated this issue when comparing/reviewing Intel's SSD's vs. parts from OCZ which uses a certain JMicron controller. See here: http://www.anandtech.com/showdoc.aspx?i=3403&p=7
You should probably just read the entire review.

It is therefore possible that your issue has more to do with the behaviour of your SSD during writes than the kernel scheduler or anything else.