Are all_max_peak percentile calculations wrong?

[butch42]

Hello,

as far as I checked and understood the source code the
calculations for 'all_max_peak' are wrong currently.

For type 'max' as well as 'all_max_peak' function
nth_percentile() is called with one $local_data_id,
returning a nth_percentile for the given datasource as
well as a calculated field 'nth_percentile_maximum'.

When using 'max', this field 'nth_percentile_maximum' is
used and this looks right for me.

When using 'all_max_peak', the nth_cache is iterated, seeking
for a maximum. But within each iteration the nth_percentile_maximum
is used which should be the same for every local_data_id of that
RRD. I think the iteration should seek for the maximum of the
n'th percentiles of the respective data sources.


The following patch makes that happen:

root@...# diff -u lib/graph_variables.php.20121008-dist lib/graph_variables.php
--- lib/graph_variables.php.20121008-dist 2012-10-25 15:18:56.000000000 +0200
+++ lib/graph_variables.php 2012-10-25 15:58:42.000000000 +0200
@@ -366,8 +366,8 @@
}elseif ($regexp_match_array[4] == "all_max_peak") {
for ($t=0;($t<count($graph_items));$t++) {
if ((preg_match("/(AREA|STACK|LINE[123])/", $graph_item_types{$graph_items[$t]["graph_type_id"]})) && (!empty($graph_items[$t]["data_template_rrd_id"]))) {
- if (! empty($nth_cache{$graph_items[$t]["local_data_id"]}["nth_percentile_maximum"])) {
- $local_nth = $nth_cache{$graph_items[$t]["local_data_id"]}["nth_percentile_maximum"];
+ if (! empty($nth_cache{$graph_items[$t]["local_data_id"]}{$graph_items[$t]["data_source_name"]})) {
+ $local_nth = $nth_cache{$graph_items[$t]["local_data_id"]}{$graph_items[$t]["data_source_name"]};
$local_nth = ($regexp_match_array[2] == "bits") ? $local_nth * 8 : $local_nth;
$local_nth /= pow(10,intval($regexp_match_array[3]));


Is anyone able and willing to comment on this, check
my investigations or correct me?

I did post this to the mailinglist already, but the forum seems to be
more active than the list to mee.


Regards
Florian