rtla/osnoise: Add support to adjust the tracing_thresh

osnoise uses the tracing_thresh parameter to define the delta between
two reads of the time to be considered a noise.

Add support to get and set the tracing_thresh from osnoise tools.

Link: https://lkml.kernel.org/r/715ad2a53fd40e41bab8c3f1214c1a94e12fb595.1646247211.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>

tools/tracing/rtla/src/osnoise.c

@@ -655,6 +655,85 @@ void osnoise_put_print_stack(struct osnoise_context *context)
 	context->orig_print_stack = OSNOISE_OPTION_INIT_VAL;
 }
 
+/*
+ * osnoise_get_tracing_thresh - read and save the original "tracing_thresh"
+ */
+static long long
+osnoise_get_tracing_thresh(struct osnoise_context *context)
+{
+	long long tracing_thresh;
+
+	if (context->tracing_thresh != OSNOISE_OPTION_INIT_VAL)
+		return context->tracing_thresh;
+
+	if (context->orig_tracing_thresh != OSNOISE_OPTION_INIT_VAL)
+		return context->orig_tracing_thresh;
+
+	tracing_thresh = osnoise_read_ll_config("tracing_thresh");
+	if (tracing_thresh < 0)
+		goto out_err;
+
+	context->orig_tracing_thresh = tracing_thresh;
+	return tracing_thresh;
+
+out_err:
+	return OSNOISE_OPTION_INIT_VAL;
+}
+
+/*
+ * osnoise_set_tracing_thresh - set "tracing_thresh"
+ */
+int osnoise_set_tracing_thresh(struct osnoise_context *context, long long tracing_thresh)
+{
+	long long curr_tracing_thresh = osnoise_get_tracing_thresh(context);
+	int retval;
+
+	if (curr_tracing_thresh == OSNOISE_OPTION_INIT_VAL)
+		return -1;
+
+	retval = osnoise_write_ll_config("tracing_thresh", tracing_thresh);
+	if (retval < 0)
+		return -1;
+
+	context->tracing_thresh = tracing_thresh;
+
+	return 0;
+}
+
+/*
+ * osnoise_restore_tracing_thresh - restore the original "tracing_thresh"
+ */
+void osnoise_restore_tracing_thresh(struct osnoise_context *context)
+{
+	int retval;
+
+	if (context->orig_tracing_thresh == OSNOISE_OPTION_INIT_VAL)
+		return;
+
+	if (context->orig_tracing_thresh == context->tracing_thresh)
+		goto out_done;
+
+	retval = osnoise_write_ll_config("tracing_thresh", context->orig_tracing_thresh);
+	if (retval < 0)
+		err_msg("Could not restore original tracing_thresh\n");
+
+out_done:
+	context->tracing_thresh = OSNOISE_OPTION_INIT_VAL;
+}
+
+/*
+ * osnoise_put_tracing_thresh - restore original values and cleanup data
+ */
+void osnoise_put_tracing_thresh(struct osnoise_context *context)
+{
+	osnoise_restore_tracing_thresh(context);
+
+	if (context->orig_tracing_thresh == OSNOISE_OPTION_INIT_VAL)
+		return;
+
+	context->orig_tracing_thresh = OSNOISE_OPTION_INIT_VAL;
+}
+
 /*
  * enable_osnoise - enable osnoise tracer in the trace_instance
  */
@@ -716,6 +795,9 @@ struct osnoise_context *osnoise_context_alloc(void)
 	context->orig_print_stack	= OSNOISE_OPTION_INIT_VAL;
 	context->print_stack		= OSNOISE_OPTION_INIT_VAL;
 
+	context->orig_tracing_thresh	= OSNOISE_OPTION_INIT_VAL;
+	context->tracing_thresh		= OSNOISE_OPTION_INIT_VAL;
+
 	osnoise_get_context(context);
 
 	return context;
@@ -741,6 +823,7 @@ void osnoise_put_context(struct osnoise_context *context)
 	osnoise_put_stop_total_us(context);
 	osnoise_put_timerlat_period_us(context);
 	osnoise_put_print_stack(context);
+	osnoise_put_tracing_thresh(context);
 
 	free(context);
 }

tools/tracing/rtla/src/osnoise.h

@@ -23,6 +23,10 @@ struct osnoise_context {
 	long long		orig_timerlat_period_us;
 	long long		timerlat_period_us;
 
+	/* 0 as init value */
+	long long		orig_tracing_thresh;
+	long long		tracing_thresh;
+
 	/* -1 as init value because 0 is disabled */
 	long long		orig_stop_us;
 	long long		stop_us;
@@ -67,6 +71,10 @@ int osnoise_set_timerlat_period_us(struct osnoise_context *context,
 				   long long timerlat_period_us);
 void osnoise_restore_timerlat_period_us(struct osnoise_context *context);
 
+int osnoise_set_tracing_thresh(struct osnoise_context *context,
+			       long long tracing_thresh);
+void osnoise_restore_tracing_thresh(struct osnoise_context *context);
+
 void osnoise_restore_print_stack(struct osnoise_context *context);
 int osnoise_set_print_stack(struct osnoise_context *context,
 			    long long print_stack);