Re: [PATCH] sched: Further restrict the preemption modes

Steven Rostedt
2026-02-27T14:53:20Z

On Fri, 27 Feb 2026 14:39:42 +0530
Shrikanth Hegde <sshegde@linux.ibm.com> wrote:

> I am afraid we will have trace all functions to begin with (which is expensive), but filter
> out those which took minimal time (like less than a 1s or so). that would eventually leave only a
> few functions that actually took more than 1s(that should have limited overhead).

Well, I think the detection can be done with timings between schedules.
What's the longest running task without any voluntary schedule. Then you
can add function graph tracing to it where it can possibly trigger in the
location that detected the issue.

On a detection of a long schedule, a stack trace can be recorded. Using
that stack trace, you could use the function graph tracer to see what is
happening.

Anyway, something to think about, and this could be a topic at this years
Linux Plumbers Tracing MC ;-)

-- Steve