Re: [PATCH] Documentation/rtla: Document SIGINT behavior
út 24. 3. 2026 v 16:22 odesílatel Steven Rostedt 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) > > -- Steve > Thanks for looking at this. Tomas
Re: [PATCH] Documentation/rtla: Document SIGINT behavior
On Tue, 24 Mar 2026 13:32:29 +0100 Tomas Glozar wrote: > The behavior of RTLA on receiving SIGINT is currently undocumented. > > Describe it in RTLA's common appendix that appears in man pages for all > RTLA tools to avoid confusion. > > Suggested-by: Attila Fazekas > Signed-off-by: Tomas Glozar > --- > > 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. > > Documentation/tools/rtla/common_appendix.txt | 21 > 1 file changed, 21 insertions(+) > > diff --git a/Documentation/tools/rtla/common_appendix.txt > b/Documentation/tools/rtla/common_appendix.txt > index 53cae7537537..8c90a02588e7 100644 > --- a/Documentation/tools/rtla/common_appendix.txt > +++ b/Documentation/tools/rtla/common_appendix.txt > @@ -1,5 +1,26 @@ > .. SPDX-License-Identifier: GPL-2.0 > > +SIGINT BEHAVIOR > +=== > + > +On the first SIGINT, RTLA exits after collecting all outstanding samples up > to > +the point of receiving the signal. > + > +When receiving more than one SIGINT, RTLA discards any outstanding samples, > and > +exits while displaying only samples that have already been processed. > + > +If SIGINT is received during RTLA cleanup, RTLA exits immediately via > +the default signal handler. > + > +Note: For the purpose of SIGINT behavior, the expiry of duration specified > via > +the -d/--duration option is treated as equivalent to receiving a SIGINT. For > +example, a SIGINT received after duration expired but samples have not been > +processed yet will drop any outstanding samples. > + > +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? > + > EXIT STATUS > === > Other than that ... LGTM, Reviewed-by: Steven Rostedt (Google) -- Steve
[PATCH] Documentation/rtla: Document SIGINT behavior
The behavior of RTLA on receiving SIGINT is currently undocumented. Describe it in RTLA's common appendix that appears in man pages for all RTLA tools to avoid confusion. Suggested-by: Attila Fazekas Signed-off-by: Tomas Glozar --- Note: There was a bug in SIGINT behavior, fixed in upcoming commit [1]. [1] https://lore.kernel.org/linux-trace-kernel/[email protected]/ Documentation/tools/rtla/common_appendix.txt | 21 1 file changed, 21 insertions(+) diff --git a/Documentation/tools/rtla/common_appendix.txt b/Documentation/tools/rtla/common_appendix.txt index 53cae7537537..8c90a02588e7 100644 --- a/Documentation/tools/rtla/common_appendix.txt +++ b/Documentation/tools/rtla/common_appendix.txt @@ -1,5 +1,26 @@ .. SPDX-License-Identifier: GPL-2.0 +SIGINT BEHAVIOR +=== + +On the first SIGINT, RTLA exits after collecting all outstanding samples up to +the point of receiving the signal. + +When receiving more than one SIGINT, RTLA discards any outstanding samples, and +exits while displaying only samples that have already been processed. + +If SIGINT is received during RTLA cleanup, RTLA exits immediately via +the default signal handler. + +Note: For the purpose of SIGINT behavior, the expiry of duration specified via +the -d/--duration option is treated as equivalent to receiving a SIGINT. For +example, a SIGINT received after duration expired but samples have not been +processed yet will drop any outstanding samples. + +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. + EXIT STATUS === -- 2.53.0
