Me and a colleague were discussing just last night the thorny problem of how we work out which of many competing processes are using disk access - causing contention on the disk, so that everything queues up, and more and more disk access is caused... not really a lot of tools in linux todo that... (If we knew the worst offenders, then we could focus our effort on making them more efficient - having to put instrumentation in each process is really time consuming).
.. so reading this article was timely. Looks like systemtap would enable us to quickly home in on the big disk users..
.. the article quite clearly states that to get the best out of systemtap you need these patches, so when Mr Morton himself makes this sort of criticism, then its a bit of a concern.
Despite all that, I'm off to look at systemtap in a bit more detail (it's lack of ubiquity has put me off before), but the lack of decent tools for working out what is really going on in a complex system is pretty frustrating (I'm still suffering from the lack of the "W" flag in the output of ps(1) to show which processes are swapped out - I understand why it doesn't show that any more - but when your system goes into swap, it's useful to see which processes are being paged out.. I suspect systemtap might be able to help with this too).