út 24. 3. 2026 v 16:22 odesílatel Steven Rostedt <[email protected]> napsal:
> >
> > Note: There was a bug in SIGINT behavior, fixed in upcoming commit [1].
> >
> > [1]
> > https://lore.kernel.org/linux-trace-kernel/[email protected]/
>
> Hmm, this may be interesting enough to add to the change log itself.
>
I thought about that, but it felt a bit redundant, since the other
patch will also be a part of the commit history. I see that some
documentation patches do mention the commit that introduced the
change. Here, it is only the SIGINT during cleanup part that got
changed (segfault/undefined behavior -> default handler) so it might
make sense.
> > +Also note that when using the timerlat tool in BPF mode, samples are
> > processed
> > +in-kernel; RTLA only copies them out to display them to the user. A second
> > +SIGINT does not affect in-kernel sample aggregation.
>
> But does it affect the user space side of reading that information?
>
No, it shouldn't, the pattern for both timerlat-top and timerlat-hist is:
while(stop_tracing) {
timerlat_bpf_wait(...);
timerlat_{top,hist}_pull_bpf_data(...);
...
}
The BPF program is detached after this, so all data gathered up to the
point of the SIGINT will be displayed. A second SIGINT does not affect
it, since it calls tracefs_iterate_stop() which stops
tracefs_iterate_raw_events(). It does not stop
timelat_{top,hist}_pull_bpf_data() - which is aggregated anyway, so
stopping it would just leave a part of the histogram/top empty.
> > +
> > EXIT STATUS
> > ===========
> >
>
> Other than that ... LGTM,
>
> Reviewed-by: Steven Rostedt (Google) <[email protected]>
>
> -- Steve
>
Thanks for looking at this.
Tomas
