linux-stable.git/tools/tracing/rtla/src/timerlat_hist.c, branch v6.15

rtla: Unify apply_config between top and hist

2025-03-26T14:36:39+00:00

The functions osnoise_top_apply_config and osnoise_hist_apply_config, as
well as timerlat_top_apply_config and timerlat_hist_apply_config, are
mostly the same.

Move common part from them into separate functions osnoise_apply_config
and timerlat_apply_config.

For rtla-timerlat, also unify params->user_hist and params->user_top
into one field called params->user_data, and move several fields used
only by timerlat-top into the top-only section of struct
timerlat_params.

Cc: Luis Goncalves 
Link: https://lore.kernel.org/20250320092500.101385-3-tglozar@redhat.com
Signed-off-by: Tomas Glozar 
Reviewed-by: John Kacur 
Signed-off-by: Steven Rostedt (Google)

rtla: Fix segfault in save_trace_to_file call

2025-03-26T14:35:20+00:00

Running rtla with exit on threshold, but without saving trace leads to a
segmenetation fault:

$ rtla timerlat hist -T 10
...
Max timerlat IRQ latency from idle: 4.29 us in cpu 0
Segmentation fault

This is caused by null pointer deference in the call of
save_trace_to_file, which attempts to dereference an uninitialized
osnoise_tool variable:

save_trace_to_file(record->trace.inst, params->trace_output);
                   ^ this is uninitialized if params->trace_output is
                     not set

Fix this by not attempting to dereference "record" if it is NULL and
passing NULL instead. As a safety measure, the first field is also
checked for NULL inside save_trace_to_file.

Cc: John Kacur 
Cc: Luis Goncalves 
Cc: Costa Shulyupin 
Link: https://lore.kernel.org/20250313141034.299117-1-tglozar@redhat.com
Fixes: dc4d4e7c72d1 ("rtla: Refactor save_trace_to_file")
Signed-off-by: Tomas Glozar 
Signed-off-by: Steven Rostedt (Google)

rtla: Refactor save_trace_to_file

2025-03-04T19:17:19+00:00

The functions osnoise_hist_main(), osnoise_top_main(),
timerlat_hist_main(), and timerlat_top_main() are lengthy and contain
duplicated code.

Refactor by consolidating the duplicate lines into the
save_trace_to_file() function.

Cc: Daniel Bristot de Oliveira 
Cc: John Kacur 
Cc: "Luis Claudio R. Goncalves" 
Cc: Eder Zulian 
Cc: Dan Carpenter 
Cc: Gabriele Monaco 
Link: https://lore.kernel.org/20250219115138.406075-1-costa.shul@redhat.com
Signed-off-by: Costa Shulyupin 
Reviewed-by: Tomas Glozar 
Tested-by: Tomas Glozar 
Signed-off-by: Steven Rostedt (Google)

rtla/timerlat_hist: Use BPF to collect samples

2025-03-04T17:35:18+00:00

Collect samples using BPF program instead of pulling them from tracefs.

If the osnoise:timerlat_sample tracepoint is unavailable or the BPF
program fails to load for whatever reason, rtla falls back to the old
implementation.

The collection of samples using the BPF program is fully self-contained
and requires no activity of the userspace part of rtla during the
measurement. Thus, instead of waking up every second to collect samples,
rtla simply sleeps until woken up by a signal or threshold overflow.

Cc: John Kacur 
Cc: Luis Goncalves 
Cc: Gabriele Monaco 
Cc: Clark Williams 
Link: https://lore.kernel.org/20250218145859.27762-6-tglozar@redhat.com
Signed-off-by: Tomas Glozar 
Signed-off-by: Steven Rostedt (Google)

rtla/timerlat: Unify params struct

2025-03-04T17:35:17+00:00

Instead of having separate structs timerlat_top_params and
timerlat_hist_params, use one struct timerlat_params for both.

This allows code using the structs to be shared between timerlat-top and
timerlat-hist.

Cc: John Kacur 
Cc: Luis Goncalves 
Cc: Gabriele Monaco 
Cc: Clark Williams 
Link: https://lore.kernel.org/20250218145859.27762-2-tglozar@redhat.com
Signed-off-by: Tomas Glozar 
Signed-off-by: Steven Rostedt (Google)

Merge tag 'trace-tools-v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2025-01-26T22:25:58+00:00

Pull rv and tools/rtla updates from Steven Rostedt:

 - Add a test suite to test the tool

   Add a small test suite that can be used to test rtla's basic features
   to at least have something to test when applying changes.

 - Automate manual steps in monitor creation

   While creating a new monitor in RV, besides generating code from
   dot2k, there are a few manual steps which can be tedious and error
   prone, like adding the tracepoints, makefile lines and kconfig, or
   selecting events that start the monitor in the initial state.

   Updates were made to try and automate as much as possible among those
   steps to make creating a new RV monitor much quicker. It is still
   requires to select proper tracepoints, this step is harder to
   automate in a general way and, in several cases, would still need
   user intervention.

 - Have rtla timerlat hist and top set OSNOISE_WORKLOAD flag

   Have both rtla-timerlat-hist and rtla-timerlat-top set
   OSNOISE_WORKLOAD to the proper value ("on" when running with -k,
   "off" when running with -u) every time the option is available
   instead of setting it only when running with -u.

   This prevents rtla timerlat -k from giving no results when
   NO_OSNOISE_WORKLOAD is set, either manually or by an abnormally
   exited earlier run of rtla timerlat -u.

 - Stop rtla timerlat on signal properly when overloaded

   There is an issue where if rtla is run on machines with a high number
   of CPUs (100+), timerlat can generate more samples than rtla is able
   to process via tracefs_iterate_raw_events. This is especially common
   when the interval is set to 100us (rteval and cyclictest default) as
   opposed to the rtla default of 1000us, but also happens with the rtla
   default.

   Currently, this leads to rtla hanging and having to be terminated
   with SIGTERM. SIGINT setting stop_tracing is not enough, since more
   and more events are coming and tracefs_iterate_raw_events never
   exits.

   To fix this: Stop the timerlat tracer on SIGINT/SIGALRM to ensure no
   more events are generated when rtla is supposed to exit.

   Also on receiving SIGINT/SIGALRM twice, abort iteration immediately
   with tracefs_iterate_stop, making rtla exit right away instead of
   waiting for all events to be processed.

 - Account for missed events

   Due to tracefs buffer overflow, it can happen that rtla misses
   events, making the tracing results inaccurate.

   Count both the number of missed events and the total number of
   processed events, and display missed events as well as their
   percentage. The numbers are displayed for both osnoise and timerlat,
   even though for the earlier, missed events are generally not
   expected.

   For hist, the number is displayed at the end of the run; for top, it
   is displayed on each printing of the top table.

 - Changes to make osnoise more robust

   There was a dependency in the code that the first field of the
   osnoise_tool structure was the trace field. If that that ever
   changed, then the code work break. Change the code to encapsulate
   this dependency where the code that uses the structure does not have
   this dependency.

* tag 'trace-tools-v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (22 commits)
  rtla: Report missed event count
  rtla: Add function to report missed events
  rtla: Count all processed events
  rtla: Count missed trace events
  tools/rtla: Add osnoise_trace_is_off()
  rtla/timerlat_top: Set OSNOISE_WORKLOAD for kernel threads
  rtla/timerlat_hist: Set OSNOISE_WORKLOAD for kernel threads
  rtla/osnoise: Distinguish missing workload option
  rtla/timerlat_top: Abort event processing on second signal
  rtla/timerlat_hist: Abort event processing on second signal
  rtla/timerlat_top: Stop timerlat tracer on signal
  rtla/timerlat_hist: Stop timerlat tracer on signal
  rtla: Add trace_instance_stop
  tools/rtla: Add basic test suite
  verification/dot2k: Implement event type detection
  verification/dot2k: Auto patch current kernel source
  verification/dot2k: Simplify manual steps in monitor creation
  rv: Simplify manual steps in monitor creation
  verification/dot2k: Add support for name and description options
  verification/dot2k: More robust template variables
  ...

rtla: Report missed event count

2025-01-24T18:47:07+00:00

Print how many events were missed by trace buffer overflow in the main
instance at the end of the run (for hist) or during the run (for top).

Cc: John Kacur 
Cc: Luis Goncalves 
Link: https://lore.kernel.org/20250123142339.990300-5-tglozar@redhat.com
Signed-off-by: Tomas Glozar 
Tested-by: Gabriele Monaco 
Signed-off-by: Steven Rostedt (Google)

tools/rtla: Add osnoise_trace_is_off()

2025-01-24T18:46:11+00:00

All of the users of trace_is_off() passes in &record->trace as the second
parameter, where record is a pointer to a struct osnoise_tool. This record
could be NULL and there is a hidden dependency that the trace field is the
first field to allow &record->trace to work with a NULL record pointer.

In order to make this code a bit more robust, as record shouldn't be
dereferenced if it is NULL, even if the code does work, create a new
function called osnoise_trace_is_off() that takes the pointer to a
struct osnoise_tool as its second parameter. This way it can properly test
if it is NULL before it dereferences it.

The old function trace_is_off() is removed and the function
osnoise_trace_is_off() is added into osnoise.c which is what the
struct osnoise_tool is associated with.

Cc: John Kacur 
Cc: "Luis Claudio R. Goncalves" 
Cc: Eder Zulian 
Cc: Dan Carpenter 
Cc: Tomas Glozar 
Cc: Gabriele Monaco 
Link: https://lore.kernel.org/20250115180055.2136815-1-costa.shul@redhat.com
Signed-off-by: Costa Shulyupin 
Signed-off-by: Steven Rostedt (Google)

rtla/timerlat_hist: Set OSNOISE_WORKLOAD for kernel threads

2025-01-24T18:45:55+00:00

When using rtla timerlat with userspace threads (-u or -U), rtla
disables the OSNOISE_WORKLOAD option in
/sys/kernel/tracing/osnoise/options. This option is not re-enabled in a
subsequent run with kernel-space threads, leading to rtla collecting no
results if the previous run exited abnormally:

$ rtla timerlat hist -u
^\Quit (core dumped)
$ rtla timerlat hist -k -d 1s
Index
over:
count:
min:
avg:
max:
ALL:        IRQ       Thr       Usr
count:        0         0         0
min:          -         -         -
avg:          -         -         -
max:          -         -         -

The issue persists until OSNOISE_WORKLOAD is set manually by running:
$ echo OSNOISE_WORKLOAD > /sys/kernel/tracing/osnoise/options

Set OSNOISE_WORKLOAD when running rtla with kernel-space threads if
available to fix the issue.

Cc: stable@vger.kernel.org
Cc: John Kacur 
Cc: Luis Goncalves 
Link: https://lore.kernel.org/20250107144823.239782-3-tglozar@redhat.com
Fixes: ed774f7481fa ("rtla/timerlat_hist: Add timerlat user-space support")
Signed-off-by: Tomas Glozar 
Signed-off-by: Steven Rostedt (Google)

rtla/timerlat_hist: Abort event processing on second signal

2025-01-24T18:45:31+00:00

If either SIGINT is received twice, or after a SIGALRM (that is, after
timerlat was supposed to stop), abort processing events currently left
in the tracefs buffer and exit immediately.

This allows the user to exit rtla without waiting for processing all
events, should that take longer than wanted, at the cost of not
processing all samples.

Cc: John Kacur 
Cc: Luis Goncalves 
Cc: Gabriele Monaco 
Link: https://lore.kernel.org/20250116144931.649593-5-tglozar@redhat.com
Signed-off-by: Tomas Glozar 
Signed-off-by: Steven Rostedt (Google)