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rtla/trace: Save event histogram output to a file

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The hist: trigger generates a histogram in the file sys/event/hist.
If the hist: trigger is used, automatically save the histogram output of
the event sys:event in the sys_event_hist.txt file.

Link: https://lkml.kernel.org/r/b5c906af31d4e022ffe87fb0848fac5c089087c8.1646247211.git.bristot@kernel.org

Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: Clark Williams <williams@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Daniel Bristot de Oliveira 2022-03-02 20:01:36 +01:00 committed by Steven Rostedt (Google)
parent 44f3a37d1d
commit 761916fd02
2 changed files with 62 additions and 1 deletions
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10
Documentation/tools/rtla/common_options.rst
View file

@ -23,7 +23,15 @@
Filter the previous **-e** *sys:event* event with *<filter>*. For further information about event filtering see https://www.kernel.org/doc/html/latest/trace/events.html#event-filtering.
**--trigger** *<trigger>*
Enable a trace event trigger to the previous **-e** *sys:event*. For further information about event trigger see https://www.kernel.org/doc/html/latest/trace/events.html#event-triggers.
Enable a trace event trigger to the previous **-e** *sys:event*.
If the *hist:* trigger is activated, the output histogram will be automatically saved to a file named *system_event_hist.txt*.
For example, the command:
rtla <command> <mode> -t -e osnoise:irq_noise --trigger="hist:key=desc,duration/1000:sort=desc,duration/1000:vals=hitcount"
Will automatically save the content of the histogram associated to *osnoise:irq_noise* event in *osnoise_irq_noise_hist.txt*.
For further information about event trigger see https://www.kernel.org/doc/html/latest/trace/events.html#event-triggers.
**-P**, **--priority** *o:prio|r:prio|f:prio|d:runtime:period*

53
tools/tracing/rtla/src/trace.c
View file

@ -296,6 +296,57 @@ static void trace_event_disable_filter(struct trace_instance *instance,
tevent->event ? : "*", tevent->filter);
}
/*
* trace_event_save_hist - save the content of an event hist
*
* If the trigger is a hist: one, save the content of the hist file.
*/
static void trace_event_save_hist(struct trace_instance *instance,
struct trace_events *tevent)
{
int retval, index, out_fd;
mode_t mode = 0644;
char path[1024];
char *hist;
if (!tevent)
return;
/* trigger enables hist */
if (!tevent->trigger)
return;
/* is this a hist: trigger? */
retval = strncmp(tevent->trigger, "hist:", strlen("hist:"));
if (retval)
return;
snprintf(path, 1024, "%s_%s_hist.txt", tevent->system, tevent->event);
printf(" Saving event %s:%s hist to %s\n", tevent->system, tevent->event, path);
out_fd = creat(path, mode);
if (out_fd < 0) {
err_msg(" Failed to create %s output file\n", path);
return;
}
hist = tracefs_event_file_read(instance->inst, tevent->system, tevent->event, "hist", 0);
if (!hist) {
err_msg(" Failed to read %s:%s hist file\n", tevent->system, tevent->event);
goto out_close;
}
index = 0;
do {
index += write(out_fd, &hist[index], strlen(hist) - index);
} while (index < strlen(hist));
free(hist);
out_close:
close(out_fd);
}
/*
* trace_event_disable_trigger - disable an event trigger
*/
@ -314,6 +365,8 @@ static void trace_event_disable_trigger(struct trace_instance *instance,
debug_msg("Disabling %s:%s trigger %s\n", tevent->system,
tevent->event ? : "*", tevent->trigger);
trace_event_save_hist(instance, tevent);
snprintf(trigger, 1024, "!%s\n", tevent->trigger);
retval = tracefs_event_file_write(instance->inst, tevent->system,