On Thu, 18 Feb 2021 17:21:19 -0500
Michael Jeanson [off-list ref] wrote:

This series only implements the tracepoint infrastructure required to
allow tracers to handle page faults. Modifying each tracer to handle
those page faults would be a next step after we all agree on this piece
of instrumentation infrastructure.

I started taking a quick look at this, and came up with the question: how
do you allow preemption when dealing with per-cpu buffers or storage to
record the data?

That is, perf, bpf and ftrace are all using some kind of per-cpu data, and
this is the reason for the need to disable preemption. What's the solution
that LTTng is using for this? I know it has a per cpu buffers too, but does
it have some kind of "per task" buffer that is being used to extract the
data that can fault?

-- Steve