Document what vertical dashed line in SVG means

[paulmenzel]

[Moved from https://github.com/systemd/systemd/issues/8502.]

Submission type

• Request for enhancement (RFE)

systemd version the issue has been seen with

238

Used distribution

Debian Sid/unstable

In case of bug report: Expected behaviour you didn't see

An explanation, what the vertical dashed line in the SVG means.

In case of bug report: Unexpected behaviour you saw

No explanation.

In case of bug report: Steps to reproduce the problem

Start system with init=/lib/systemd/systemd-bootchart.

[jamuir]

There is an explanation in the code that mentions Intel Atom processors:

systemd-bootchart/src/svg.c

Lines 1208 to 1233 in a15bcaf

	/*
	* our definition of "idle":
	*
	* if for (hz / 2) we've used less CPU than (interval / 2) ...
	* defaults to 4.0%, which experimentally, is where atom idles
	*/
	if ((crt - brt) < (interval / 2.0)) {
	idletime = ps->sample->sampledata->sampletime - graph_start;
	fprintf(of, "\n<!-- idle detected at %.03f seconds -->\n", idletime);
	fprintf(of, "<line class=\"idle\" x1=\"%.03f\" y1=\"%.03f\" x2=\"%.03f\" y2=\"%.03f\" />\n",
	time_to_graph(idletime),
	-arg_scale_y,
	time_to_graph(idletime),
	ps_to_graph(pcount) + arg_scale_y);
	if (idletime > 1.0)
	fprintf(of, "<text class=\"idle\" x=\"%.03f\" y=\"%.03f\">%.01fs</text>\n",
	time_to_graph(idletime) + 5.0,
	ps_to_graph(pcount) + arg_scale_y,
	idletime);
	else
	fprintf(of, "<text class=\"idle\" x=\"%.03f\" y=\"%.03f\">%.01fms</text>\n",
	time_to_graph(idletime) + 5.0,
	ps_to_graph(pcount) + arg_scale_y,
	to_ms(idletime));
	break;
	}

I agree that this should be documented.

Could you open a PR?