Hello Stephen, Am 2011-04-03 15:00:03, schrieb Stephen McCamant <s...@csail.mit.edu> > SJR> the system I'm working on does not have swap space (for a > SJR> reason), yet xmem still switches to include a horizontal line for > SJR> the physical/swap boundary. Obviously, the upper half is empty; > SJR> it even switches back sometimes. This appears to be a "slightly > SJR> above 100%" condition due to rounding errors. > > I've been annoyed by this too. It's possible that a rounding problem > could cause this behavior in some circumstances, though I think the > height calculation uses "1.0 + swap", so if swap is exactly 0 the > result should be exactly 1.0. On machines with swap space it can also > happen that Linux uses a very small but non-zero amount of swap, but > in looking at the code today I noticed there's also a bug that causes > this even in the absence of those. When the chart is redrawn in > response to an exposure event, the code that recomputes the integer > scale "rounds" using the equivalent of "floor(x) + 1" instead of > "ceil(x)", so if the floating-point "maximum height seen" is exactly > 1.0, it will be rounded to 2. (This code is on line 400 of > MemStripChart.c in the etch 1.20-25 source, in the function > repaint_window). > > Using ceil() to do the rounding would probably fix your version of the > problem. I think the best fix, though, might be to change the > calculation to "ceil(x - epsilon)", where epsilon is chosen to be > about the amount that would show up as a single pixel in the display: > in other words, we don't want to increase the scale unless there would > actually be some swap usage visible.
----[ '/Development/xmem/xmem-1.20/MemStripChart.c' ]-------------------
<snip>
static int
repaint_window(w, left, width)
MemStripChartWidget w;
int left, width;
{
int i, j;
int next = w->mem_strip_chart.interval;
int scale = w->mem_strip_chart.scale;
int scalewidth = 0;
/* Compute the minimum scale required to graph the data, but don't go
lower than min_scale. */
if (w->mem_strip_chart.interval != 0 || scale <=
(int)w->mem_strip_chart.max_value)
scale = ((int) (w->mem_strip_chart.max_value)) + 1;
------------------------------------------------------------------------
So this is line 400 but I do not understand what to change... :-/
I have searched for ceil() or ceiling() but not found it.
Which header must I ad to get it?
------------------------------------------------------------------------
if (scale < w->mem_strip_chart.min_scale)
scale = w->mem_strip_chart.min_scale;
if (scale != w->mem_strip_chart.scale) {
w->mem_strip_chart.scale = scale;
left = 0;
width = next;
scalewidth = w->core.width;
SetPoints(w);
if (XtIsRealized ((Widget) w))
XClearWindow (XtDisplay (w), XtWindow (w));
}
if (XtIsRealized((Widget)w)) {
Display *dpy = XtDisplay(w);
Window win = XtWindow(w);
width += left - 1;
if (!scalewidth) scalewidth = width;
if (next < ++width) width = next;
/* Draw data point lines. */
for (i = left; i < width; i++) {
DrawMemStrip(w, i, w->mem_strip_chart.valuedata[i]);
}
/* Draw graph reference lines */
for (i = 1; i < w->mem_strip_chart.scale; i++) {
j = i * ((int)w->core.height / w->mem_strip_chart.scale);
XDrawLine(dpy, win, w->mem_strip_chart.hiGC, left, j, scalewidth,
j);
}
}
return(next);
}
<snip>
------------------------------------------------------------------------
> -- Stephen
Thanks, Greetings and nice Day/Evening
Michelle Konzack
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