rtla: Add hwnoise tool

The hwnoise tool is a special mode for the osnoise top tool.

hwnoise dispatches the osnoise tracer and displays a summary of the noise.
The difference is that it runs the tracer with the OSNOISE_IRQ_DISABLE
option set, thus only allowing only hardware-related noise, resulting in
a simplified output. hwnoise has the same features of osnoise.

An example of the tool's output:

 # rtla hwnoise -c 1-11 -T 1 -d 10m -q
                                           Hardware-related Noise
 duration:   0 00:10:00 | time is in us
 CPU Period       Runtime        Noise  % CPU Aval   Max Noise   Max Single          HW          NMI
   1 #599       599000000          138    99.99997           3            3           4           74
   2 #599       599000000           85    99.99998           3            3           4           75
   3 #599       599000000           86    99.99998           4            3           6           75
   4 #599       599000000           81    99.99998           4            4           2           75
   5 #599       599000000           85    99.99998           2            2           2           75

Link: https://lkml.kernel.org/r/2d6f49a6f3a4f8b51b2c806458b1cff71ad4d014.1675805361.git.bristot@kernel.org

Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

1 files changed, 117 insertions, 0 deletions

diff --git a/tools/tracing/rtla/src/osnoise.c b/tools/tracing/rtla/src/osnoise.c
index 4dee343909b1..3ca7a3853943 100644
--- a/tools/tracing/rtla/src/osnoise.c
+++ b/tools/tracing/rtla/src/osnoise.c
@@ -734,6 +734,113 @@ void osnoise_put_tracing_thresh(struct osnoise_context *context)
 	context->orig_tracing_thresh = OSNOISE_OPTION_INIT_VAL;
 }
 
+static int osnoise_options_get_option(char *option)
+{
+	char *options = tracefs_instance_file_read(NULL, "osnoise/options", NULL);
+	char no_option[128];
+	int retval = 0;
+	char *opt;
+
+	if (!options)
+		return OSNOISE_OPTION_INIT_VAL;
+
+	/*
+	 * Check first if the option is disabled.
+	 */
+	snprintf(no_option, sizeof(no_option), "NO_%s", option);
+
+	opt = strstr(options, no_option);
+	if (opt)
+		goto out_free;
+
+	/*
+	 * Now that it is not disabled, if the string is there, it is
+	 * enabled. If the string is not there, the option does not exist.
+	 */
+	opt = strstr(options, option);
+	if (opt)
+		retval = 1;
+	else
+		retval = OSNOISE_OPTION_INIT_VAL;
+
+out_free:
+	free(options);
+	return retval;
+}
+
+static int osnoise_options_set_option(char *option, bool onoff)
+{
+	char no_option[128];
+
+	if (onoff)
+		return tracefs_instance_file_write(NULL, "osnoise/options", option);
+
+	snprintf(no_option, sizeof(no_option), "NO_%s", option);
+
+	return tracefs_instance_file_write(NULL, "osnoise/options", no_option);
+}
+
+static int osnoise_get_irq_disable(struct osnoise_context *context)
+{
+	if (context->opt_irq_disable != OSNOISE_OPTION_INIT_VAL)
+		return context->opt_irq_disable;
+
+	if (context->orig_opt_irq_disable != OSNOISE_OPTION_INIT_VAL)
+		return context->orig_opt_irq_disable;
+
+	context->orig_opt_irq_disable = osnoise_options_get_option("OSNOISE_IRQ_DISABLE");
+
+	return context->orig_opt_irq_disable;
+}
+
+int osnoise_set_irq_disable(struct osnoise_context *context, bool onoff)
+{
+	int opt_irq_disable = osnoise_get_irq_disable(context);
+	int retval;
+
+	if (opt_irq_disable == OSNOISE_OPTION_INIT_VAL)
+		return -1;
+
+	if (opt_irq_disable == onoff)
+		return 0;
+
+	retval = osnoise_options_set_option("OSNOISE_IRQ_DISABLE", onoff);
+	if (retval < 0)
+		return -1;
+
+	context->opt_irq_disable = onoff;
+
+	return 0;
+}
+
+static void osnoise_restore_irq_disable(struct osnoise_context *context)
+{
+	int retval;
+
+	if (context->orig_opt_irq_disable == OSNOISE_OPTION_INIT_VAL)
+		return;
+
+	if (context->orig_opt_irq_disable == context->opt_irq_disable)
+		goto out_done;
+
+	retval = osnoise_options_set_option("OSNOISE_IRQ_DISABLE", context->orig_opt_irq_disable);
+	if (retval < 0)
+		err_msg("Could not restore original OSNOISE_IRQ_DISABLE option\n");
+
+out_done:
+	context->orig_opt_irq_disable = OSNOISE_OPTION_INIT_VAL;
+}
+
+static void osnoise_put_irq_disable(struct osnoise_context *context)
+{
+	osnoise_restore_irq_disable(context);
+
+	if (context->orig_opt_irq_disable == OSNOISE_OPTION_INIT_VAL)
+		return;
+
+	context->orig_opt_irq_disable = OSNOISE_OPTION_INIT_VAL;
+}
+
 /*
  * enable_osnoise - enable osnoise tracer in the trace_instance
  */
@@ -798,6 +905,9 @@ struct osnoise_context *osnoise_context_alloc(void)
 	context->orig_tracing_thresh	= OSNOISE_OPTION_INIT_VAL;
 	context->tracing_thresh		= OSNOISE_OPTION_INIT_VAL;
 
+	context->orig_opt_irq_disable	= OSNOISE_OPTION_INIT_VAL;
+	context->opt_irq_disable	= OSNOISE_OPTION_INIT_VAL;
+
 	osnoise_get_context(context);
 
 	return context;
@@ -824,6 +934,7 @@ void osnoise_put_context(struct osnoise_context *context)
 	osnoise_put_timerlat_period_us(context);
 	osnoise_put_print_stack(context);
 	osnoise_put_tracing_thresh(context);
+	osnoise_put_irq_disable(context);
 
 	free(context);
 }
@@ -958,3 +1069,9 @@ usage:
 	osnoise_usage(1);
 	exit(1);
 }
+
+int hwnoise_main(int argc, char *argv[])
+{
+	osnoise_top_main(argc, argv);
+	exit(0);
+}