linux-stable.git/tools/tracing/rtla/src/timerlat_hist.c, branch v6.14

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)

rtla/timerlat_hist: Stop timerlat tracer on signal

2025-01-24T18:45:14+00:00

Currently, when either SIGINT from the user or SIGALRM from the duration
timer is caught by rtla-timerlat, stop_tracing is set to break out of
the main loop. This is not sufficient for cases where the timerlat
tracer is producing more data than rtla can consume, since in that case,
rtla is looping indefinitely inside tracefs_iterate_raw_events, never
reaches the check of stop_tracing and hangs.

In addition to setting stop_tracing, also stop the timerlat tracer on
received signal (SIGINT or SIGALRM). This will stop new samples so that
the existing samples may be processed and tracefs_iterate_raw_events
eventually exits.

Cc: stable@vger.kernel.org
Cc: John Kacur 
Cc: Luis Goncalves 
Cc: Gabriele Monaco 
Link: https://lore.kernel.org/20250116144931.649593-3-tglozar@redhat.com
Fixes: 1eeb6328e8b3 ("rtla/timerlat: Add timerlat hist mode")
Signed-off-by: Tomas Glozar 
Signed-off-by: Steven Rostedt (Google)

rtla/timerlat: Fix histogram ALL for zero samples

2024-12-27T16:21:46+00:00

rtla timerlat hist currently computers the minimum, maximum and average
latency even in cases when there are zero samples. This leads to
nonsensical values being calculated for maximum and minimum, and to
divide by zero for average.

A similar bug is fixed by 01b05fc0e5f3 ("rtla/timerlat: Fix histogram
report when a cpu count is 0") but the bug still remains for printing
the sum over all CPUs in timerlat_print_stats_all.

The issue can be reproduced with this command:

$ rtla timerlat hist -U -d 1s
Index
over:
count:
min:
avg:
max:
Floating point exception (core dumped)

(There are always no samples with -U unless the user workload is
created.)

Fix the bug by omitting max/min/avg when sample count is zero,
displaying a dash instead, just like we already do for the individual
CPUs. The logic is moved into a new function called
format_summary_value, which is used for both the individual CPUs
and for the overall summary.

Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/20241127134130.51171-1-tglozar@redhat.com
Fixes: 1462501c7a8 ("rtla/timerlat: Add a summary for hist mode")
Signed-off-by: Tomas Glozar 
Signed-off-by: Steven Rostedt (Google)

rtla/timerlat: Do not set params->user_workload with -U

2024-11-19T13:56:59+00:00

Since commit fb9e90a67ee9 ("rtla/timerlat: Make user-space threads
the default"), rtla-timerlat has been defaulting to
params->user_workload if neither that or params->kernel_workload is set.
This has unintentionally made -U, which sets only params->user_hist/top
but not params->user_workload, to behave like -u unless -k is set,
preventing the user from running a custom workload.

Example:
$ rtla timerlat hist -U -c 0 &
[1] 7413
$ python sample/timerlat_load.py 0
Error opening timerlat fd, did you run timerlat -U?
$ ps | grep timerlatu
7415 pts/4    00:00:00 timerlatu/0

Fix the issue by checking for params->user_top/hist instead of
params->user_workload when setting default thread mode.

Link: https://lore.kernel.org/20241021123140.14652-1-tglozar@redhat.com
Fixes: fb9e90a67ee9 ("rtla/timerlat: Make user-space threads the default")
Signed-off-by: Tomas Glozar 
Signed-off-by: Steven Rostedt (Google)

rtla/timerlat: Add --deepest-idle-state for hist

2024-10-17T21:13:15+00:00

Support limiting deepest idle state also for timerlat-hist.

Link: https://lore.kernel.org/20241017140914.3200454-6-tglozar@redhat.com
Signed-off-by: Tomas Glozar 
Signed-off-by: Steven Rostedt (Google)

rtla/timerlat: Make timerlat_hist_cpu->*_count unsigned long long

2024-10-11T17:09:57+00:00

Do the same fix as in previous commit also for timerlat-hist.

Link: https://lore.kernel.org/20241011121015.2868751-2-tglozar@redhat.com
Reported-by: Attila Fazekas 
Signed-off-by: Tomas Glozar 
Signed-off-by: Steven Rostedt (Google)