Fun with tracepoints

I think the problem is more that individual kernel developers don't really
(need to) look at the whole system or be responsible for it, just a one
corner of it. On commercial operating systems, there are dedicated people
who look after the whole thing and need to make sure that the whole thing
works fine (and this responsibility gives them influence over the
operating system implementation to make sure that these tools get done &
available).

If you're looking just at one or some parts of the whole system, things
like LTT (or to some extent Systemtap[1]) that try to get an overview of
what happens in the whole system may seem too large / complex /
intrusive / bloated. "I just need this specific info from the block
layer" (or memory subsystem, or ...). And then they write their own NIH
tracing for that single thing that doesn't much benefit others, or
somebody who wants to make sense out of the whole system.

Note: I have gotten useful info both from LTT and LTTng (lttng.org) + it's
finally getting easier to apply to kernel... LTTv plays a large part in
this too as one can easily zoom into details etc.

[1] Systemtap seems nice, but it doesn't have the post-processing /
visualization for the whole system like LTT does. I see it more like a
tool to do more specific analysis tools. However, for this kind of stuff
it's a bit too complicated (e.g. in embedded environments where you don't
want to run stap / compile the scripts on the device itself etc), so no
wonder devs write their own tracing...