út 22. 7. 2025 v 17:30 odesílatel Steven Rostedt [off-list ref] napsal:

On Tue, 22 Jul 2025 09:03:24 +0200
Tomas Glozar [off-list ref] wrote:

quoted

Of course, this is just an implementational limitation of the timerlat
tracer. If timerlat had an event (like osnoise's "sample_threshold")
triggered on threshold overflow and if it is possible to wait on it
even without BPF, rtla could wait on that for both BPF and non-BPF
mode instead of what it is currently doing.

Right. Is this something you may want?

I don't think it is that important. Non-BPF mode is mostly as a
fallback for users of rtla on older kernels which don't have the
osnoise:timerlat_sample trace event. Those are (I assume) mostly users
of LTS distributions who run newer rtla from a container. Adding a new
event wouldn't help in their case.

The only users who would benefit from that are those who don't have
BPF or libbpf. If there is interest from using low-latency actions on
threshold in such settings, I'm not against implementing a threshold
overflow tracepoint and supporting it in rtla for triggering actions
on threshold.

Tomas