From 0d5407168827cb293abd9f0b5ecd406b16783f01 Mon Sep 17 00:00:00 2001
From: mh <mh@immerda.ch>
Date: Wed, 11 Aug 2010 09:59:09 +0200
Subject: introduce caching for xen plugins

calls to the xen binaries such as xm are quite heavy and we
therefore cache now a lot of the data that is generated for these
plugins and use them as well for the other ones.
---
 files/plugins/xen-cpu | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

(limited to 'files/plugins/xen-cpu')

diff --git a/files/plugins/xen-cpu b/files/plugins/xen-cpu
index 0ef301e..b456a14 100755
--- a/files/plugins/xen-cpu
+++ b/files/plugins/xen-cpu
@@ -28,6 +28,10 @@ use strict;
 
 $ENV{PATH} = '/bin:/usr/bin:/usr/sbin';
 
+# we cache xm list for 5 min for perfomance reasons
+system('((find /var/lib/munin/plugin-state/xm_list.state -mmin -5 2>&1 | grep -qE \'^\/var\/lib\/munin\/plugin-state\/xm_list\.state$\') && [ `cat /var/lib/munin/plugin-state/xm_list.state | wc -l` -gt 1 ]) || /usr/sbin/xm list | grep -v "^Name .* Console$" > /var/lib/munin/plugin-state/xm_list.state');
+system('((find /var/lib/munin/plugin-state/xm_top.state -mmin -5 2>&1 | grep -qE \'^\/var\/lib\/munin\/plugin-state\/xm_top\.state$\') && [ `cat /var/lib/munin/plugin-state/xm_top.state | wc -l` -gt 1 ]) || /usr/sbin/xentop -b -i1 > /var/lib/munin/plugin-state/xm_top.state');
+
 my $arg; undef($arg);
 if (defined($ARGV[0])) {
         $arg = 'config' if ($ARGV[0] eq 'config');
@@ -53,8 +57,9 @@ if (defined($ARGV[0])) {
                         'graph_info' => 'Display the % of CPU Usage for each domain',
                 );
 
-                my @domains = `$XM list`;
-                shift(@domains); # we dont need the header line
+                my @domains = `cat /var/lib/munin/plugin-state/xm_list.state`;
+		# the header line is not in the cached file
+                #shift(@domains); # we dont need the header line
                 my $cnt = "0";
                 foreach my $domain ( @domains ) {
                         my ($dom,undef) = split(/\s/, $domain, 2);
@@ -81,16 +86,7 @@ if (defined($ARGV[0])) {
 
 # Nothing was passed as an argument, so let's just return the proper values
 
-my @chunks; undef(@chunks);
-
-{
-        # run the xentop command a few times because the first reading is not always accurate
-        local $/ = undef;
-        @chunks = split(/^xentop - .*$/m, `$XMTOP -b -i2 -d2`);
-}
-
-# Take only the last run of xentop
-my @stats = split (/\n/,pop(@chunks));
+my @stats = `cat /var/lib/munin/plugin-state/xm_top.state`;
 
 # remove the first 4 items that are junk that we don't need.
 shift(@stats);
-- 
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