Re: [PATCH v1] rtla: Save trace when option `--trace` is specified

[Steven Rostedt]

On Mon, 3 Mar 2025 16:34:21 +0100
Tomas Glozar <tglozar@xxxxxxxxxx> wrote:

> pá 28. 2. 2025 v 2:05 odesílatel Steven Rostedt <rostedt@xxxxxxxxxxx> napsal:
> >
> > Without tracing being off, this can run forever if the events come in
> > faster than it can be recorded. And save trace uses the "trace" file, which
> > is slow to read.
> >
> > Are you sure you want that?
> >  
> 
> Isn't that a different problem though? As far as I'm aware, it
> shouldn't matter at all whether tracing is stopped on the main
> instance for collecting the trace from the record instance.
> 
> If the record instance generates a lot of samples, this can already
> run forever, regardless of whether tracing is stopped on the main
> instance or not. This should be a separate fix.

Not sure what you mean by "main instance"?

The code being changed is:

-	if (osnoise_trace_is_off(tool, record)) {
+	if (osnoise_trace_is_off(tool, record))
 		printf("rtla osnoise hit stop tracing\n");
-		if (params->trace_output) {
-			printf("  Saving trace to %s\n", params->trace_output);
-			save_trace_to_file(record->trace.inst, params->trace_output);
-		}
+	if (params->trace_output) {
+		printf("  Saving trace to %s\n", params->trace_output);
+		save_trace_to_file(record->trace.inst, params->trace_output);
 	}

Where osnoise_trace_is_off() is:

bool osnoise_trace_is_off(struct osnoise_tool *tool, struct osnoise_tool *record)
{
        /*
         * The tool instance is always present, it is the one used to collect
         * data.
         */
        if (!tracefs_trace_is_on(tool->trace.inst))
                return true;

        /*
         * The trace record instance is only enabled when -t is set. IOW, when the system
         * is tracing.
         */
        return record && !tracefs_trace_is_on(record->trace.inst);
}


Which returns true if the tool->trace.inst is on and false otherwise.

-- Steve